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Radiologic Science for TechnologistsPhysics, Biology, and Protection

Radiologic Science for TechnologistsPhysics, Biology, and Protection 10th Edition

By: Stewart Carlyle Bushong
ISBN-10: 0323081355
/ ISBN-13: 9780323081351
Edition: 10th Edition
Language: English
				
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Front Matter

    • Reviewers
    • Dedication
    • Preface
    • Purpose and Content
    • Historical Perspective
    • New to This Edition
    • Ancillaries
    • Student Workbook
    • Evolve Resources
    • Mosby’s Radiography Online
    • A Note on the Text
    • Acknowledgments

Part I Radiologic Physics

    • Chapter 1 Essential Concepts of Radiologic Science
    • Objectives
    • Nature of Our Surroundings
    • Matter and Energy
    • A Penguin Tale by Benjamin Archer, PHD
    • FIGURE 1-1 The blade of a guillotine offers a dramatic example of both potential and kinetic energy. When the blade is pulled to its maximum height and is locked into place, it has potential energy. When the blade is allowed to fall, the potential energy is released as kinetic energy.
    • Mass-Energy
    • FIGURE 1-2 Ionization is the removal of an electron from an atom. The ejected electron and the resultant positively charged atom together are called an ion pair.
    • Sources of Ionizing Radiation
    • FIGURE 1-3 The contribution of various sources to the average U.S. population radiation dose, 1990. We will return to this very important pie chart in Chapter 37.
    • FIGURE 1-4 Radiation exposure at waist level throughout the United States.
    • Discovery of X-Rays
    • FIGURE 1-5 The type of Crookes tube Roentgen used when he discovered x-rays. Cathode rays (electrons) leaving the cathode are attracted by high voltage to the anode, where they produce x-rays and fluorescent light.
    • FIGURE 1-6 The hand shown in this radiograph belongs to Mrs. Roentgen. This first indication of the possible medical applications of x-rays was made within a few days of the discovery.
    • FIGURE 1-7 This photograph records the first medical x-ray examination in the United States. A young patient, Eddie McCarthy of Hanover, New Hampshire, broke his wrist while skating on the Connecticut River and submitted to having it photographed by the “X-light.” With him are (left to right) Professor E.B. Frost, Dartmouth College, and his brother, Dr. G.D. Frost, Medical Director, Mary Hitchcock Hospital. The apparatus was assembled by Professor F.G. Austin in his physics laboratory at Reed Hall, Dartmouth College, on February 3, 1896.
    • Development of Modern Radiology
    • FIGURE 1-8 Thomas Edison is seen viewing the hand of his unfortunate assistant, Clarence Dally, through a fluoroscope of his own design. Dally’s hand rests on the box that contains the x-ray tube.
    • Reports of Radiation Injury
    • Basic Radiation Protection
    • Filtration
    • Collimation
    • Box 1-1 Important Dates in the Development of Modern Radiology
    • Box 1-2 The Ten Commandments of Radiation Protection
    • Intensifying Screens
    • Protective Apparel
    • Gonadal Shielding
    • Protective Barriers
    • Standard Units of Measurement
    • FIGURE 1-9 The general purpose radiographic and fluoroscopic imaging system includes an overhead radiographic tube (A) and a fluoroscopic examining table (B) with an x-ray tube under the table. Some of the more common radiation protection devices are the lead curtain (C), the Bucky slot cover (D), a leaded apron and gloves (E), and the protective viewing window (F). The location of the image intensifier (G) and of associated imaging equipment is shown.
    • FIGURE 1-10 Base quantities support derived quantities, which in turn support the special quantities of radiologic science.
    • TABLE 1-1 System of Units
    • Length
    • Mass
    • Time
    • Units
    • TABLE 1-2 Special Quantities of Radiologic Science and Their Units
    • Mechanics
    • FIGURE 1-11 Drag racing provides a familiar example of the relationships among initial velocity, final velocity, acceleration, and time.
    • Velocity
    • Velocity
    • Average Velocity
    • Acceleration
    • Acceleration
    • Newton’s Laws of Motion
    • FIGURE 1-12 Newton’s first law states that a body at rest will remain at rest and a body in motion will continue in motion until acted on by an outside force.
    • FIGURE 1-13 Newton’s second law states that the force applied to move an object is equal to the mass of the object multiplied by the acceleration.
    • Force
    • FIGURE 1-14 Crazed student technologists performing a routine physics experiment to prove Newton’s third law.
    • Weight
    • Weight
    • Momentum
    • Momentum
    • FIGURE 1-15 The conservation of momentum occurs with every billiard shot.
    • Work
    • Work
    • Power
    • Power
    • Energy
    • Kinetic Energy
    • Potential Energy
    • FIGURE 1-16 Potential energy results from the position of an object. Kinetic energy is the energy of motion. A, Maximum potential energy, no kinetic energy. B, Potential energy and kinetic energy. C, Maximum kinetic energy, no potential energy.
    • Heat
    • TABLE 1-3 Summary of Quantities, Equations, and Units Used in Mechanics
    • Heat Transfer
    • FIGURE 1-17 Three scales used to represent temperature. Celsius is the adopted scale for weather reporting everywhere except the United States. Kelvin is the scientific scale.
    • Temperature Scales
    • Approximate Temperature Conversion
    • FIGURE 1-18 The energy thermometer scales temperature and energy together.
    • Terminology for Radiologic Science
    • TABLE 1-4 Standard Scientific and Engineering Prefixes*
    • Numeric Prefixes
    • Radiologic Units
    • Air Kerma (Kinetic Energy Released in Matter) (Gya)
    • FIGURE 1-19 Radiation is emitted by radioactive material. The quantity of radioactive material is measured in becquerel. Radiation quantity is measured in gray or sievert, depending on the precise use.
    • TABLE 1-5 Special Quantities of Radiologic Science and Their Associated Special Units
    • Absorbed Dose (Gyt)
    • Sievert (Sv)
    • FIGURE 1-20 Scales for effective dose.
    • Becquerel (Bq)
    • The Diagnostic Imaging Team
    • Summary
    • Challenge Questions
    • Box 1-3 Task Inventory for Radiography as Required for Examination by the American Registry of Radiologic Technologists
    • Patient Care
    • Radiation Protection
    • Equipment Operation
    • Image Production
    • Equipment Maintenance
    • Radiographic Procedures
    • Chapter 2 The Structure of Matter
    • Objectives
    • Centuries of Discovery
    • Greek Atom
    • FIGURE 2-1 The size of objects varies enormously. The range of sizes in nature requires that scientific notation be used because more than 40 orders of magnitude are necessary.
    • Dalton Atom
    • FIGURE 2-2 Symbolic representation of the substances and essences of matter as viewed by the ancient Greeks.
    • FIGURE 2-3 Through the years, the atom has been represented by many symbols. A, The Greeks envisioned four different atoms, representing air, fire, earth, and water. These triangular symbols were adopted by medieval alchemists. B, Dalton’s atoms had hooks and eyes to account for chemical combination. C, Thomson’s model of the atom has been described as a plum pudding, with the plums representing the electrons. D, The Bohr atom has a small, dense, positively charged nucleus surrounded by electrons at precise energy levels.
    • Thomson Atom
    • FIGURE 2-4 Periodic table of elements.
    • Bohr Atom
    • Fundamental Particles
    • FIGURE 2-5 The nucleus consists of protons and neutrons, which are made of quarks bound together by gluons.
    • TABLE 2-1 Important Characteristics of the Fundamental Particles
    • Atomic Structure
    • FIGURE 2-6 Atoms are composed of neutrons and protons in the nucleus and electrons in specific orbits surrounding the nucleus. Shown here are the three smaller atoms and the largest naturally occurring atom, uranium.
    • Electron Arrangement
    • FIGURE 2-7 Ionization of a carbon atom by an x-ray leaves the atom with a net electric charge of +1. The ionized atom and the released electron are called an ion pair.
    • TABLE 2-2 Maximum Number of Electrons That Can Occupy Each Electron Shell
    • Maximum Electrons Per Shell
    • Electron Arrangement
    • Electron Binding Energy
    • FIGURE 2-8 Electrons revolve about the nucleus in fixed orbits or shells. Electrostatic attraction results in a specific electron path about the nucleus.
    • FIGURE 2-9 Atomic configurations and approximate electron binding energies for three radiologically important atoms. As atoms get bigger, electrons in a given shell become more tightly bound.
    • Atomic Nomenclature
    • Isotopes
    • FIGURE 2-10 Protocol for representing elements in a molecule.
    • TABLE 2-3 Characteristics of Some Elements Important to Radiologic Science
    • Isobar
    • Isotone
    • TABLE 2-4 Characteristics of Various Nuclear Arrangements
    • Isomer
    • Combinations of ATOMS
    • Molecule
    • Compound
    • FIGURE 2-11 Matter has many levels of organization. Atoms combine to make molecules and molecules combine to make tissues.
    • Radioactivity
    • Radioactivity
    • Radioisotopes
    • FIGURE 2-12 131I decays to 131Xe with the emission of a beta particle.
    • FIGURE 2-13 The decay of 226Ra to 222Rn is accompanied by alpha emission.
    • Radioactive Half-life
    • Half-life
    • FIGURE 2-14 131I decays with a half-life of 8 days. This linear graph allows estimation of radioactivity only for a short time.
    • FIGURE 2-15 This semilog graph is useful for estimating the radioactivity of 131I at any given time.
    • FIGURE 2-16 The radioactivity after any period can be estimated from the linear (A) or the semilog (B) graph. The original quantity is assigned a value of 100%, and the time of decay is expressed in units of half-life.
    • FIGURE 2-17 Carbon is a biologically active element. A small fraction of all carbon is the radioisotope 14C. As a tree grows, 14C is incorporated into the wood in proportion to the amount of 14C in the atmosphere. When the tree dies, further exchange of 14C with the atmosphere does not take place. If the dead wood is preserved by petrification, the 14C content diminishes as it radioactively decays. This phenomenon serves as the basis for radiocarbon dating.
    • Radioactive Decay
    • TABLE 2-5 General Classification of Ionizing Radiation
    • Types of Ionizing Radiation
    • Particulate Radiation
    • Alpha Particle
    • Beta Particle
    • TABLE 2-6 Characteristics of Several Types of Ionizing Radiation
    • Electromagnetic Radiation
    • Summary
    • FIGURE 2-18 Different types of radiation ionize matter with different degrees of efficiency. Alpha particles represent highly ionizing radiation with a very short range in matter. Beta particles do not ionize so readily and have a longer range. X-rays have a low ionization rate and a very long range.
    • Challenge Questions
    • Chapter 3 Electromagnetic Energy
    • Objectives
    • Photons
    • Velocity and Amplitude
    • FIGURE 3-1 These three sine waves are identical except for their amplitudes.
    • Frequency and Wavelength
    • FIGURE 3-2 Sine waves are associated with many naturally occurring phenomena in addition to electromagnetic energy.
    • FIGURE 3-3 Moving one end of a rope in a whiplike fashion will set into motion sine waves that travel down the rope to the fastened end. An observer, midway, can determine the frequency of oscillation by counting the crests or valleys that pass a point (A) per unit time.
    • FIGURE 3-4 These three sine waves have different wavelengths. The shorter the wavelength (λ), the higher is the frequency.
    • FIGURE 3-5 Relationships among velocity (v), frequency (f), and wavelength (lambda) for any sine wave.
    • The Wave Equation
    • Electromagnetic Wave Equation
    • Electromagnetic Wave Equation
    • Electromagnetic Spectrum
    • Measurement of the Electromagnetic Spectrum
    • Visible Light
    • Radiofrequency
    • FIGURE 3-6 The electromagnetic spectrum extends over more than 25 orders of magnitude. This chart shows the values of energy, frequency, and wavelength and identifies the three imaging windows.
    • FIGURE 3-7 When it passes through a prism, white light is refracted into its component colors. These colors have wavelengths that extend from approximately 400 to 700 nm.
    • Ionizing Radiation
    • FIGURE 3-8 X-rays are produced outside the nucleus of excited atoms.
    • FIGURE 3-9 Gamma rays are produced inside the nucleus of radioactive atoms.
    • FIGURE 3-10 The electromagnetic relationship triangle h is Planck’s constant (defined later in this chapter).
    • Wave-Particle Duality
    • Wave Model: Visible Light
    • FIGURE 3-11 A small object dropped into a smooth pond creates waves of short wavelength. A large object creates waves of much longer wavelength.
    • FIGURE 3-12 Energy is reflected when waves crash into a bulkhead. It is absorbed by a beach. It is partially absorbed or attenuated by a line of pilings. Light is also reflected, absorbed, or attenuated, depending on the composition of the surface on which it is incident.
    • FIGURE 3-13 Objects absorb light in three degrees: not at all (transmission), partially (attenuation), and completely (absorption). The objects associated with these degrees of absorption are called transparent, translucent, and opaque, respectively.
    • FIGURE 3-14 Structures that attenuate x-rays are described as radiolucent or radiopaque, depending on the relative degree of x-ray transmission or absorption, respectively.
    • FIGURE 3-15 The inverse square law describes the relationship between radiation intensity and distance from the radiation source.
    • Inverse Square Law
    • Inverse Square Law
    • Particle Model: Quantum Theory
    • TABLE 3-1 Examples of the Wide Range of X-rays Produced by Application in Medicine, Research, and Industry
    • FIGURE 3-16 All electromagnetic radiation, including x-rays, can be visualized as two perpendicular sine waves that travel in a straight line at the speed of light. One of the sine waves represents an electric field and the other a magnetic field.
    • Planck’s Quantum Equation
    • Equivalent Planck’s Equation
    • Matter and Energy
    • Relativity
    • FIGURE 3-17 Mass and energy are two forms of the same medium. This scale shows the equivalence of mass measured in kilograms to energy measured in electron volts.
    • Summary
    • Challenge Questions
    • Chapter 4 Electricity, Magnetism, and Electromagnetism
    • Objectives
    • Electrostatics
    • FIGURE 4-1 The x-ray imaging system converts electrical energy into electromagnetic energy.
    • FIGURE 4-2 Electric energy can be converted from or to other forms by various devices, such as the battery (A) from chemical energy, the motor (B) to mechanical energy, and the barbecue (C) to thermal energy.
    • FIGURE 4-3 Running a comb briskly through your hair may cause both your hair and the comb to become electrified through the transfer of electrons from hair to comb. The electrified condition may make it possible to pick up small pieces of paper with the comb and may cause one’s hair to stand on end.
    • FIGURE 4-4 Electrified clouds are the source of lightning in a storm.
    • FIGURE 4-5 Early radiologic technologists are shown in this scene from the original Frankenstein movie (1931).
    • Electrostatic Laws
    • Coulomb’s Law
    • FIGURE 4-6 Electric fields radiate out from a positive charge (A) and toward a negative charge (B). Like charges repel one another (C and D). Unlike charges attract one another (E). Uncharged particles do not have an electric field (F).
    • Coulomb’s Law
    • Electric Potential
    • FIGURE 4-7 Cross section of an electrified copper wire, showing that the surface of the wire has excessive electrostatic charges.
    • FIGURE 4-8 Electrostatic charges are concentrated on surfaces of sharpest curvature. The cattle prod is a device that takes advantage of this electrostatic law.
    • Electrodynamics
    • Electric Circuits
    • FIGURE 4-9 The electrical resistance of a conductor (Cu) and a superconductor (NbTi) as a function of temperature.
    • FIGURE 4-10 Recent years have seen a dramatic rise in the critical temperature for superconducting materials.
    • TABLE 4-1 Four Electric States of Matter
    • TABLE 4-2 Symbol and Function of Electric Circuit Elements
    • FIGURE 4-11 Series circuit and its basic rules.
    • Ohm’s Law
    • FIGURE 4-12 Parallel circuit and its basic rules.
    • Rules for Series Circuits
    • Rules for a Parallel Circuit
    • FIGURE 4-13 Representation of direct current. Electrons flow in one direction only. The graph of the associated electric waveform is a straight line.
    • FIGURE 4-14 Representation of alternating current. Electrons flow alternately in one direction and then the other. Alternating current is represented graphically by a sinusoidal electric waveform.
    • Electric Power
    • Electric Power
    • Magnetism
    • FIGURE 4-15 A moving charged particle induces a magnetic field in a plane perpendicular to its motion.
    • FIGURE 4-16 When a charged particle moves in a circular or elliptical path, the perpendicular magnetic field moves with the charged particle.
    • FIGURE 4-17 A spinning charged particle will induce a magnetic field along the axis of spin.
    • FIGURE 4-18 A, In ferromagnetic material, the magnetic dipoles are randomly oriented. B, This changes when the dipoles are brought under the influence of an external magnetic field.
    • FIGURE 4-19 A, Imaginary lines of force. B, These lines of force are undisturbed by nonmagnetic material. C, They are deviated by ferromagnetic material.
    • FIGURE 4-20 A method for using an electromagnet to render ceramic bricks magnetic.
    • FIGURE 4-21 Developments in permanent magnet design have resulted in a great increase in magnetic field intensity.
    • TABLE 4-3 Four Magnetic States of Matter
    • FIGURE 4-22 If a single magnet is broken into smaller and smaller pieces, baby magnets result.
    • FIGURE 4-23 Demonstration of magnetic lines of force with iron filings.
    • Magnetic Laws
    • Magnetic Induction
    • FIGURE 4-24 The imaginary lines of the magnetic field leave the north pole and enter the south pole.
    • FIGURE 4-25 Ferromagnetic material such as iron attracts magnetic lines of induction, whereas nonmagnetic material such as copper does not.
    • Electromagnetism
    • FIGURE 4-26 A compass reacts with the Earth as though it were a bar magnet seeking the North Pole.
    • FIGURE 4-27 A, Original Voltaic pile. B, A modern dry cell. C, Symbol for a battery.
    • FIGURE 4-28 Oersted’s experiment. A, With no electric current in the wire, the compass points north. B, With electric current, the compass points toward the wire.
    • FIGURE 4-29 Magnetic field lines form concentric circles around the current-carrying wire.
    • FIGURE 4-30 Magnetic field lines are concentrated on the inside of the loop.
    • FIGURE 4-31 Magnetic field lines of a solenoid.
    • FIGURE 4-32 Magnetic field lines of an electromagnet.
    • FIGURE 4-33 Schematic description of Faraday’s experiment shows how a moving magnetic field induces an electric current.
    • Electromagnetic Induction
    • Faraday’s Law
    • FIGURE 4-34 Radio reception is based on the principles of electromagnetic induction.
    • FIGURE 4-35 Principal parts of an induction motor.
    • Electromechanical Devices
    • The Transformer
    • FIGURE 4-36 An electromagnet that incorporates a closed iron core produces a closed magnetic field that is primarily confined to the core.
    • Transformer Law
    • Effect of Transformer Law Effect on Current
    • FIGURE 4-37 Type of transformers. A, Closed-core transformer. B, Autotransformer. C, Shell-type transformer.
    • Summary
    • Challenge Questions

Part II X-Radiation

    • Chapter 5 The X-ray Imaging System
    • Objectives
    • FIGURE 5-1 Types of diagnostic x-ray imaging systems. A, Tomographic. B, Trauma. C, Urologic. D, Mobile.
    • FIGURE 5-2 Flexible and mobile patient examination couch.
    • FIGURE 5-3 A fluoroscopic couch is identified by its head and foot tilt.
    • FIGURE 5-4 Plan drawing of a general-purpose x-ray examination room, showing locations of the various x-ray apparatus items. Chapter 38 considers the layout of such rooms in greater detail.
    • Operating Console
    • FIGURE 5-5 Typical operating console to control an overhead radiographic imaging system. Numbers of meters and controls depend on the complexity of the console.
    • FIGURE 5-6 Circuit diagram of the operating console, with controls and meters identified.
    • Autotransformer
    • FIGURE 5-7 Simplified diagram of an autotransformer.
    • Autotransformer Law
    • Adjustment of Kilovolt Peak (kVp)
    • Control of Milliamperage (mA)
    • FIGURE 5-8 Filament circuit for dual-filament x-ray tube.
    • Filament Transformer
    • FIGURE 5-9 The mA meter is in the x-ray tube circuit at a center tap on the output of the high-voltage step-up transformer. This ensures electrical safety.
    • Exposure Timers
    • Synchronous Timers
    • Electronic Timers
    • mAs Timers
    • FIGURE 5-10 Automatic exposure control terminates the x-ray exposure at the desired film optical density. This is done with an ionization chamber or a photodiode detector assembly.
    • Automatic Exposure Control
    • FIGURE 5-11 Solid-state radiation detectors are used to check timer accuracy.
    • High-Voltage Generator
    • FIGURE 5-12 Cutaway view of a typical high-voltage generator showing oil-immersed diodes and transformers.
    • FIGURE 5-13 Voltage induced in the secondary winding of a high-voltage step-up transformer is alternating like the primary voltage but has a higher value.
    • High-Voltage Transformer
    • Voltage Rectification
    • FIGURE 5-14 Rectifiers in most modern x-ray generators are the silicon, semiconductor type. The multiple black components on this 75-kVp high-voltage multiplier board are rectifiers.
    • FIGURE 5-15 A p-n junction semiconductor shown as a solid-state diode.
    • FIGURE 5-16 The electronic symbol for a solid-state diode.
    • FIGURE 5-17 Unrectified voltage and current waveforms on the secondary side.
    • FIGURE 5-18 Half-wave rectification.
    • FIGURE 5-19 A half-wave–rectified circuit contains one or more diodes.
    • Unrectified Voltage
    • Half-Wave Rectification
    • Full-Wave Rectification
    • Single-Phase Power
    • FIGURE 5-20 A full-wave–rectified circuit contains at least four diodes. Current is passed through the tube at 120 pulses per second.
    • FIGURE 5-21 Voltage across a full-wave–rectified circuit is always positive.
    • FIGURE 5-22 In a full-wave–rectified circuit, two diodes (A and D) conduct during the positive half-cycle, and two (B and C) conduct during the negative half-cycle.
    • Three-Phase Power
    • FIGURE 5-23 Three-phase power is a more efficient way to produce x-rays than is single-phase power. Shown are the voltage waveforms for unrectified single-phase power, unrectified three-phase power, and rectified three-phase power.
    • FIGURE 5-24 High-frequency voltage waveform.
    • High-Frequency Generator
    • Table 5-1 Characteristics of High-Frequency X-ray Generators
    • FIGURE 5-25 Inverter circuit of a high-voltage generator.
    • FIGURE 5-26 Tube voltage falls during exposure with a capacitor discharge generator.
    • Capacitor Discharge Generator
    • FIGURE 5-27
    • Falling Load Generator
    • FIGURE 5-28
    • Voltage Ripple
    • FIGURE 5-29 Voltage waveforms resulting from various power supplies. The ripple of the kilovoltage is indicated as a percentage for each waveform.
    • FIGURE 5-30 Both the number of x-rays and the x-ray energy increase as the voltage waveform increases.
    • FIGURE 5-31 Voltage waveform is smoothed by the capacitance of long high-voltage cables.
    • Power Rating
    • X-ray Circuit
    • Summary
    • FIGURE 5-32 The schematic circuit of an x-ray imaging system.
    • Challenge Questions
    • Chapter 6 The X-ray Tube
    • Objectives
    • External Components
    • FIGURE 6-1 Principal parts of a rotating anode x-ray tube.
    • Ceiling Support System
    • Floor-to-Ceiling Support System
    • C-Arm Support System
    • FIGURE 6-2 Three methods of supporting an x-ray tube. A, Ceiling support. B, Floor support. C, C-arm support.
    • FIGURE 6-3 Protective housing reduces the intensity of leakage radiation to less than 1 mGya/hr at 1 m.
    • Protective Housing
    • Glass or Metal Enclosure
    • FIGURE 6-4 A, Dual-filament cathode designed to provide focal spots of 0.5 mm and 1.5 mm. B, Schematic for a dual-filament cathode.
    • Internal Components
    • Cathode
    • Filament
    • Focusing Cup
    • FIGURE 6-5 The focusing cup is a metal shroud that surrounds the filament.
    • Filament Current
    • FIGURE 6-6 A, Without a focusing cup, the electron beam is spread beyond the anode because of mutual electrostatic repulsion among the electrons. B, With a focusing cup that is negatively charged, the electron beam is condensed and directed to the target.
    • FIGURE 6-7 The x-ray tube current is actually controlled by changing the filament current. Because of thermionic emission, a small change in filament current results in a large change in tube current.
    • FIGURE 6-8 At a given filament current, tube current reaches a maximum level called saturation current.
    • FIGURE 6-9 In a dual-focus x-ray tube, focal spot size is controlled by heating one of the two filaments.
    • Anode
    • FIGURE 6-10 All diagnostic x-ray tubes can be classified according to the type of anode. A, Stationary anode. B, Rotating anode.
    • Target
    • FIGURE 6-11 A, In a stationary anode tube, the target is embedded in the anode. B, In a rotating anode tube, the target is the rotating disc.
    • TABLE 6-1 Characteristics of X-ray Targets
    • FIGURE 6-12 A layered anode consists of a target surface backed by one or more layers to increase heat capacity.
    • Rotating Anode
    • FIGURE 6-13 Stationary anode tube with a 1-mm focal spot may have a target area of 4 mm2. A comparable 15-cm–diameter rotating anode tube can have a target area of approximately 1800 mm2, which increases the heating capacity of the tube by a factor of nearly 500.
    • FIGURE 6-14 Comparison of smooth, shiny appearances of rotating anodes when new (A) versus their appearance after failure (B–D). Examples of anode separation and surface melting shown were caused by slow rotation caused by bearing damage (B), repeated overload (C), and exceeding of maximum heat storage capacity (D).
    • FIGURE 6-15 The target of a rotating anode tube is powered by an induction motor, the principal components of which are the stator and the rotor.
    • Induction Motor
    • Line-Focus Principle
    • FIGURE 6-16 A, This very high capacity x-ray tube revolves in a bath of oil for complete heat dissipation. B, The cooling capacity is greater than any heat load. (Courtesy Siemens Medical Systems.)
    • FIGURE 6-17 The line-focus principle allows high anode heating with small effective focal spots. As the target angle decreases, so does the effective focal spot size.
    • FIGURE 6-18 Some targets have two angles to produce two focal spots. To achieve this, the filaments must be placed one above the other.
    • FIGURE 6-19 The usual shape of a focal spot is the double banana.
    • FIGURE 6-20 The heel effect results in reduced x-ray intensity on the anode side of the useful beam caused by absorption in the “heel” of the target.
    • TABLE 6-2 Nominal Focal Spot Size Compared With Maximum Acceptable Dimensions
    • Heel Effect
    • FIGURE 6-21 Posteroanterior chest images demonstrate the heel effect. A, Images taken with the cathode up (superior). B, Image with cathode down (inferior). More uniform radiographic density is obtained with the cathode positioned to the thicker side of the anatomy, as in B.
    • FIGURE 6-22 The effective focal spot changes size and shape across the projected x-ray field.
    • Off-Focus Radiation
    • FIGURE 6-23 Extrafocal x-rays result from interaction of electrons with the anode off of the focal spot.
    • X-Ray Tube Failure
    • FIGURE 6-24 An additional diaphragm is positioned close to the focal spot to reduce extrafocal radiation.
    • FIGURE 6-25 Heat from an anode is dissipated by radiation, conduction, or convection, most often radiation.
    • Rating Charts
    • Radiographic Rating Chart
    • FIGURE 6-26 Representative radiographic rating charts for a given x-ray tube. Each chart specifies the conditions of operation under which it applies.
    • Anode Cooling Chart
    • Single Phase
    • Three Phase/High Frequency
    • FIGURE 6-27 Anode cooling chart shows time required for heated anode to cool.
    • Housing Cooling Chart
    • Summary
    • Challenge Questions
    • Chapter 7 X-ray Production
    • Objectives
    • Electron Target Interactions
    • Kinetic Energy
    • FIGURE 7-1 Kinetic energy is proportional to the product of mass and velocity squared.
    • Anode Heat
    • Characteristic Radiation
    • FIGURE 7-2 Most of the kinetic energy of projectile electrons is converted to heat by interactions with outer-shell electrons of target atoms. These interactions are primarily excitations rather than ionizations.
    • FIGURE 7-3 Characteristic x-rays are produced after ionization of a K-shell electron. When an outer shell electron fills the vacancy in the K shell, an x-ray is emitted.
    • FIGURE 7-4 Atomic configuration and electron binding energies for tungsten.
    • TABLE 7-1 Characteristic X-rays of Tungsten and Their Effective Energies (keV)
    • FIGURE 7-5 Bremsstrahlung x-rays result from the interaction between a projectile electron and a target nucleus. The electron is slowed, and its direction is changed.
    • Bremsstrahlung Radiation
    • FIGURE 7-6 Over a given period, an automatic ball-throwing machine might eject 600 balls, distributed as shown.
    • X-Ray Emission Spectrum
    • FIGURE 7-7 Bar graph representing the results of observation of balls ejected by the automatic pitching machine shown in Figure 7-6. When the height of each bar is joined, a smooth emission spectrum is created.
    • FIGURE 7-8 General form of an x-ray emission spectrum.
    • FIGURE 7-9 Characteristic x-ray emission spectrum for tungsten contains 15 different x-ray energies.
    • Characteristic X-ray Spectrum
    • FIGURE 7-10 The bremsstrahlung x-ray emission spectrum extends from zero to maximum projectile electron energy, with the highest number of x-rays having approximately one third the maximum energy. The characteristic x-ray emission spectrum is represented by a line at 69 keV.
    • Bremsstrahlung X-ray Spectrum
    • Factors Affecting the X-Ray Emission Spectrum
    • Effect of mA and mAs
    • TABLE 7-2 Factors That Affect the Size and Relative Position of X-ray Emission Spectra
    • FIGURE 7-11 Change in mA or mAs results in a proportionate change in the amplitude of the x-ray emission spectrum at all energies.
    • FIGURE 7-12 Change in kVp results in an increase in the amplitude of the emission spectrum at all energies but a greater increase at high energies than at low energies. Therefore, the spectrum is shifted to the right, or high-energy, side.
    • Four Principal Factors Influencing the Shape of an X-ray Emission Spectrum
    • Effect of kVp
    • Effect of Added Filtration
    • FIGURE 7-13 Adding filtration to an x-ray tube results in reduced x-ray intensity but increased effective energy. The emission spectra represented here resulted from operation at the same mA and kVp but with different filtration.
    • Effect of Target Material
    • FIGURE 7-14 Discrete emission spectrum shifts to the right with an increase in the atomic number of the target material. The continuous spectrum increases slightly in amplitude, particularly to the high-energy side, with an increase in target atomic number.
    • Effect of Voltage Waveform
    • FIGURE 7-15 As the voltage across the x-ray tube increases from zero to its peak value, x-ray intensity and energy increase slowly at first and then rapidly as peak voltage is obtained.
    • FIGURE 7-16 Three-phase and high-frequency operations are considerably more efficient than single-phase operation. Both the x-ray intensity (area under the curve) and the effective energy (relative shift to the right) are increased. Shown are representative spectra for 92-kVp operation at constant mAs.
    • TABLE 7-3 Changes in X-ray Beam Quality and Quantity Produced by Factors That Influence the Emission Spectrum
    • Summary
    • Challenge Questions
    • Chapter 8 X-ray Emission
    • Objectives
    • X-Ray Quantity
    • X-ray Intensity
    • FIGURE 8-1 Nomogram for estimating the intensity of x-ray beams. From the position on the x-axis corresponding to the filtration of the imaging system, draw a vertical line until it intersects with the appropriate voltage (kVp). A horizontal line from that point will intersect the y-axis at the approximate x-ray intensity for the imaging system.
    • Factors That Affect X-ray Quantity
    • TABLE 8-1 Factors That Affect X-ray Quantity and Image Receptor Exposure
    • Milliampere Seconds (mAs)
    • X-Ray Quantity and mAs
    • Kilovolt Peak (kVp)
    • X-ray Quantity and kVp
    • Distance
    • X-ray Quantity and Distance
    • The Square Law
    • Filtration
    • X-Ray Quality
    • Penetrability
    • Half-Value Layer
    • FIGURE 8-2 Typical experimental arrangement for determination of half-value layer.
    • FIGURE 8-3 Data in the table are typical for half-value layer (HVL) determination. The plot of these data shows an HVL of 2.4 mm Al.
    • Steps to Determine the Half-Value Layer
    • Factors That Affect X-ray Quality
    • Kilovolt Peak (kVp)
    • TABLE 8-2 Factors That Affect X-ray Quality and Quantity
    • TABLE 8-3 Approximate Relationship Between the Kilovolt Peak and Half-Value Layer
    • Filtration
    • FIGURE 8-4 Filtration is used selectively to remove low-energy x-rays from the useful beam. Ideal filtration would remove all low-energy x-rays.
    • Types of Filtration
    • Inherent Filtration
    • Added Filtration
    • FIGURE 8-5 Total filtration consists of the inherent filtration of the x-ray tube, an added filter, and filtration achieved by the mirror of the light-localizing collimator.
    • FIGURE 8-6 Compensating filters. A, Trough filter. B, Wedge filter. C, “Bow-tie” filter for use in computed tomography. D, Conic filters for use in digital fluoroscopy.
    • FIGURE 8-7 Use of a wedge filter for examination of the foot.
    • Compensating Filters
    • FIGURE 8-8 Use of a trough filter for examination of the chest.
    • FIGURE 8-9 Arrangement of apparatus with the use of an aluminum step-wedge for serial radiography of the abdomen and lower extremities.
    • Summary
    • Challenge Questions
    • Chapter 9 X-ray Interaction with Matter
    • Objectives
    • Five X-Ray Interactions with Matter
    • Coherent Scattering
    • FIGURE 9-1 Coherent scattering is an interaction between low-energy x-rays and atoms. The x-ray loses no energy but changes direction slightly. The wavelength of the incident x-ray is equal to the wavelength of the scattered x-ray.
    • Compton Scattering
    • FIGURE 9-2 Compton scattering occurs between moderate-energy x-rays and outer-shell electrons. It results in ionization of the target atom, a change in x-ray direction, and a reduction in x-ray energy. The wavelength of the scattered x-ray is greater than that of the incident x-ray.
    • Compton Effect
    • FIGURE 9-3 The probability that an x-ray will interact through Compton scattering is about the same for atoms of soft tissue and those of bone. This probability decreases with increasing x-ray energy.
    • TABLE 9-1 Features of Compton Scattering
    • Photoelectric Effect
    • Photoelectric Effect
    • FIGURE 9-4 The photoelectric effect occurs when an incident x-ray is totally absorbed during the ionization of an inner-shell electron. The incident photon disappears, and the K-shell electron, now called a photoelectron, is ejected from the atom.
    • TABLE 9-2 Atomic Number and K-Shell Electron Binding Energy of Radiologically Important Elements
    • FIGURE 9-5 The relative probability that a given x-ray will undergo a photoelectric interaction is inversely proportional to the third power of the x-ray energy and directly proportional to the third power of the atomic number of the absorber.
    • Semilogarithmic Graphs
    • FIGURE 9-6 Relative probability for photoelectric interaction ranges over several orders of magnitude. If it is plotted in the conventional linear fashion, as here, one cannot estimate its value above an energy of approximately 30 keV.
    • TABLE 9-3 Effective Atomic Number of Materials Important to Radiologic Science
    • Cubic Relationships
    • FIGURE 9-7 Graphic scales can be linear or logarithmic. The log scale is used to plot wide ranges of values.
    • Pair Production
    • FIGURE 9-8 Pair production occurs with x-rays that have energies greater than 1.02 MeV. The x-ray interacts with the nuclear field, and two electrons that have opposite electrostatic charges are created.
    • TABLE 9-4 Features of Photoelectric Effect
    • Photodisintegration
    • Differential Absorption
    • FIGURE 9-9 Photodisintegration is an interaction between high-energy x-rays and the nucleus. The x-ray is absorbed by the nucleus, and a nuclear fragment is emitted.
    • FIGURE 9-10 Three types of x-rays are important to the making of a radiograph: those scattered by Compton interaction (A), those absorbed photoelectrically (B), and those transmitted through the patient without interaction (C).
    • FIGURE 9-11 When an x-ray is Compton scattered, the image receptor thinks it came straight from the source.
    • Dependence on Atomic Number
    • FIGURE 9-12 Radiograph of bony structures results from differential absorption between bone and soft tissue.
    • FIGURE 9-13 Graph showing the probabilities of photoelectric and Compton interactions with soft tissue and bone. The interactions of these curves indicate those x-ray energies at which the chance of photoelectric absorption equals the chance of Compton scattering.
    • Dependence on Mass Density
    • TABLE 9-5 Mass Density of Materials Important to Radiologic Science
    • FIGURE 9-14 Even if x-ray interaction were not related to atomic number (Z), differential absorption would occur because of differences in mass density.
    • TABLE 9-6 Characteristics of Differential Absorption
    • FIGURE 9-15 Interaction of x-rays by absorption and scatter is called attenuation. In this example, the x-ray beam has been attenuated 97%; 3% of the x-rays have been transmitted.
    • Contrast Examinations
    • Exponential Attenuation
    • FIGURE 9-16 Linear and semilog plots of exponential x-ray attenuation data in Figure 9-15.
    • Summary
    • Challenge Questions

Part III The Radiographic Image

    • Chapter 10 Concepts of Radiographic Image Quality
    • Objectives
    • Definitions
    • Radiographic Image Quality
    • Resolution
    • Noise
    • FIGURE 10-1 A, Hip radiograph demonstrating the mottled, grainy appearance associated with quantum mottle that results from the use of a low number of x-rays to produce the image. B, In comparison, an optimal hip image shows greater recorded detail.
    • Speed
    • Radiographic Quality Rules
    • FIGURE 10-2 Resolution, noise, and speed are interrelated characteristics of radiographic quality.
    • Film Factors
    • Characteristic Curve
    • FIGURE 10-3 Organization chart of principal factors that may affect radiographic quality.
    • FIGURE 10-4 The characteristic curve of a radiographic screen-film image receptor is the graphic relationship between optical density (OD) and radiation exposure.
    • FIGURE 10-5 Steps involved in the construction of a characteristic curve.
    • FIGURE 10-6 The digital thermometer (A), the densitometer (B), and the sensitometer (C) are the tools necessary for producing a characteristic curve and for providing routine quality control.
    • FIGURE 10-7 Relationship among log relative exposure (LRE) and relative mAs for typical radiographic screen-film image receptor. Relationship between percentage transmission and optical density (OD) is shown along the y-axis.
    • Optical Density
    • Optical Density
    • TABLE 10-1 Relationship of the Optical Density of Radiographic Film to Light Transmission Through the Film
    • FIGURE 10-8 Base and fog densities reduce radiographic image contrast and should be as low as possible.
    • FIGURE 10-9 This vicious guard dog is posed to demonstrate differences in contrast. A, Low contrast. B, Moderate contrast. C, High contrast.
    • Reciprocity Law
    • Contrast
    • FIGURE 10-10 If exposure of the film results in optical densities (ODs) that lie in the toe or shoulder region, where the slope of the curve is less, contrast is reduced.
    • FIGURE 10-11 The slope of the straight-line portion of the characteristic curve is greater for image receptor A than for image receptor B. Image receptor A has greater contrast.
    • Image Receptor Contrast
    • FIGURE 10-12 Average gradient is the slope of the line drawn between the points on the characteristic curve that correspond to optical density (OD) levels 0.25 and 2.0 above base and fog densities.
    • FIGURE 10-13 The gradient is the slope of the tangent at any point on the characteristic curve. Toe gradient is most important clinically.
    • Speed
    • FIGURE 10-14 When the gradient of the characteristic curve (A) is plotted as a function of optical density, a contrast curve (B) results.
    • FIGURE 10-15 The speed of a radiographic image receptor is a relative number based on 100 as par speed.
    • Image Receptor Speed
    • SPEED vs. mAs
    • FIGURE 10-16 The latitude of an image receptor is the exposure range over which it responds with diagnostically useful optical density (OD).
    • FIGURE 10-17 As development time or temperature increases, changes occur in the shape and relative position of the characteristic curve.
    • Box 10-1 Factors That May Affect the Finished Radiograph
    • Latitude
    • Film Processing
    • Development Time
    • FIGURE 10-18 Analysis of characteristic curves at various development times and temperatures yields relationships for contrast, speed, and fog for 90-second automatically processed film.
    • FIGURE 10-19 A shadowgraph is analogous to a radiograph.
    • Development Temperature
    • Geometric Factors
    • Geometric Factors
    • Magnification
    • Magnification Factor
    • Magnification Factor
    • FIGURE 10-20 Magnification is the ratio of image size to object size or of source-to-image receptor distance (SID) to source-to-object distance (SOD).
    • Magnification Factor
    • FIGURE 10-21 Magnification of an object positioned off the central ray is the same as that of an object on the central ray if the objects are in the same plane.
    • Minimizing Magnification
    • Distortion
    • Distortion Depends On
    • Object Thickness
    • FIGURE 10-22 Thick objects result in unequal magnification and thus greater distortion compared with thin objects.
    • FIGURE 10-23 Object thickness influences distortion. Radiographs of a disc or sphere appear as circles if the object is on the central ray. When lateral to the central axis, the disc appears as a circle and the sphere as an ellipse.
    • FIGURE 10-24 Irregular anatomy or objects such as these can cause considerable distortion when radiographed off the central ray.
    • FIGURE 10-25 Inclination of an object results in a foreshortened image.
    • Object Position
    • FIGURE 10-26 An inclined object that is positioned lateral to the central ray may be distorted severely by elongation or foreshortening.
    • FIGURE 10-27 When objects of the same size are positioned at different distances from the image receptor, spatial distortion occurs.
    • FIGURE 10-28 Focal-spot blur is caused by the effective size of the focal spot, which is larger to the cathode side of the image.
    • Focal-Spot Blur
    • FIGURE 10-29 Focal-spot blur is small when the object-to-image receptor distance (OID) is small.
    • Focal-Spot Blur
    • Heel Effect
    • FIGURE 10-30 Effective focal spot size is largest on the cathode side; therefore, focal-spot blur is greatest on the cathode side.
    • TABLE 10-2 Patient Positioning for Examinations That Can Take Advantage of the Heel Effect
    • Box 10-2 Subject Factors
    • Subject Factors
    • Subject Contrast
    • Radiographic Contrast
    • Patient Thickness
    • FIGURE 10-31 Different anatomical thicknesses contribute to subject contrast.
    • FIGURE 10-32 Radiographs of an orange, kiwi, piece of celery, and chunk of carrot show the effects of subtle differences in mass density.
    • FIGURE 10-33 Variation in tissue mass density contributes to subject contrast.
    • Tissue Mass Density
    • Effective Atomic Number
    • Object Shape
    • FIGURE 10-34 The shape of the structure under investigation contributes to absorption blur.
    • kVp
    • FIGURE 10-35 Radiographs of an aluminum step wedge (penetrometer) demonstrating change in contrast with varying voltage.
    • Motion Blur
    • Box 10-3 Procedures for Reducing Motion Blur
    • Tools for Improved Radiographic Quality
    • Patient Positioning
    • Image Receptors
    • Selection of Technique Factors
    • FIGURE 10-36 Chest radiographs demonstrating two advantages of high-voltage technique: greater latitude and margin for error.
    • TABLE 10-3 Principal Factors That May Affect the Making of a Radiograph*
    • Summary
    • Challenge Questions
    • Chapter 11 Control of Scatter Radiation
    • Objectives
    • Production of Scatter Radiation
    • kVp
    • FIGURE 11-1 Some x-rays interact with the patient and are scattered away from the image receptor (a). Others interact with the patient and are absorbed (b). X-rays that arrive at the image receptor are those transmitted through the patient without interacting (c) and those scattered in the patient (d). X-rays of types c and d are called image-forming x-rays.
    • TABLE 11-1 Percent Interaction of X-rays by Photoelectric and Compton Processes and Percent Transmission Through 10 cm of Soft Tissue
    • FIGURE 11-2 The relative contributions of photoelectric effect and Compton scattering to the radiographic image.
    • Field Size
    • Patient Thickness
    • FIGURE 11-3 Each of these skull radiographs is of acceptable quality. The technique factors for each are shown along with the resultant patient exposures.
    • FIGURE 11-4 Collimation of the x-ray beam results in less scatter radiation, reduced dose, and improved contrast resolution.
    • FIGURE 11-5 The recommended technique for lumbar spine radiography calls for collimation of the beam to the vertebral column. The full-field technique results in reduced image contrast. A, Full-field technique. B, Preferred collimated technique.
    • FIGURE 11-6 Extremity radiographs appear sharp because of less tissue and, hence, less scatter radiation. Posteroanterior view of the hand.
    • FIGURE 11-7 Relative intensity of scatter radiation increases with increasing thickness of anatomy.
    • FIGURE 11-8 When tissue is compressed, scatter radiation is reduced, resulting in a lower patient dose and improved contrast resolution.
    • Control of Scatter Radiation
    • Effect of Scatter Radiation on Image Contrast
    • FIGURE 11-9 When primary x-rays interact with the patient, x-rays are scattered from the patient in all directions.
    • FIGURE 11-10 Radiographs of a cross section of long bone. A, High contrast would result from the use of only transmitted, unattenuated x-rays. B, No contrast would result from the use of only scattered x-rays. C, Moderate contrast results from the use of both transmitted and scattered x-rays.
    • Beam Restrictors
    • Aperture Diaphragm
    • Cones and Cylinders
    • FIGURE 11-11 Three types of beam-restricting devices.
    • FIGURE 11-12 Aperture diaphragm is a fixed lead opening designed for a fixed image receptor size and constant source-to-image receptor distance (SID). SDD, source-to-diaphragm distance.
    • FIGURE 11-13 Typical trauma radiographic imaging system used for imaging the skull, spine, and extremities. Such units are flexible and adaptable for examination of many body parts.
    • FIGURE 11-14 Radiographic cones and cylinders produce restricted useful x-ray beams of circular shape.
    • Variable Aperture Collimator
    • FIGURE 11-15 Radiographs of the frontal and maxillary sinuses without a cone (A) and with a cone (B). Cones reduce scatter radiation and improve contrast resolution.
    • FIGURE 11-16 Automatic variable-aperture collimator.
    • FIGURE 11-17 Simplified schematic of a variable-aperture light-localizing collimator.
    • Total Filtration
    • Radiographic Grids
    • FIGURE 11-18 The only x-rays transmitted through a grid are those that travel in the direction of the interspace. X-rays scattered obliquely through the interspace are absorbed.
    • Grid Surface X-ray Absorption
    • FIGURE 11-19 Grid ratio is defined as the height of the grid strip (h) divided by the thickness of the interspace material (D). T, width of the grid strip.
    • FIGURE 11-20 High-ratio grids are more effective than low-ratio grids because the angle of deviation is smaller.
    • Grid Ratio
    • Grid Ratio
    • Grid Frequency
    • Grid Frequency
    • Interspace Material
    • Grid Strip
    • Grid Performance
    • Contrast Improvement Factor
    • Contrast Improvement Factor
    • Bucky Factor
    • Bucky Factor
    • Grid Types
    • Parallel Grid
    • FIGURE 11-21 A parallel grid is constructed with parallel grid strips. At a short source-to-image receptor distance (SID), some grid cutoff may occur.
    • TABLE 11-2 Approximate Bucky Factor Values for Popular Grids
    • FIGURE 11-22 With a parallel grid, optical density (OD) decreases toward the edge of the image receptor. The distance to grid cutoff is the source-to-image receptor distance (SID) divided by the grid ratio.
    • FIGURE 11-23 A, Radiograph taken with a 6:1 parallel grid at a source-to-image receptor distance (SID) of 76 cm. B, Radiograph taken with 6:1 parallel grid at an SID of 61 cm. Optical density decreases from the center to the edge of the image and to complete cutoff. (Courtesy Dawn Stark, Mississippi State University.)
    • Grid Cutoff
    • Crossed Grid
    • FIGURE 11-24 Crossed grids are fabricated by sandwiching two parallel grids together so their grid strips are perpendicular.
    • FIGURE 11-25 A focused grid is fabricated so that grid strips are parallel to the primary x-ray path across the entire image receptor.
    • Focused Grid
    • Moving Grid
    • Reciprocating Grid
    • Oscillating Grid
    • Disadvantages of Moving Grids
    • Grid Problems
    • FIGURE 11-26 Proper installation of a moving grid.
    • TABLE 11-3 Focused-Grid Misalignment
    • Off-Level Grid
    • FIGURE 11-27 If a grid is off level so that the central axis is not perpendicular to the grid, partial cutoff occurs over the entire image receptor.
    • FIGURE 11-28 When a focused grid is positioned off center, partial grid cutoff occurs over the entire image receptor.
    • Off-Center Grid
    • FIGURE 11-29 If a focused grid is not positioned at the specified focal distance, grid cutoff occurs and the optical density (OD) decreases with distance from the central ray.
    • Off-Focus Grid
    • Upside-Down Grid
    • Combined Off-Center, Off-Focus Grid
    • FIGURE 11-30 A focused grid positioned upside down should be detected on the first radiograph. Complete grid cutoff occurs except in the region of the central ray.
    • FIGURE 11-31 As the grid ratio increases, transmission of scatter radiation decreases faster than transmission of primary radiation. Therefore, cleanup of scatter radiation increases.
    • Grid Selection
    • Patient Dose
    • FIGURE 11-32 When the air-gap technique is used, the image receptor is positioned 10 to 15 cm from the patient. A large fraction of scattered x-rays does not interact with the image receptor.
    • TABLE 11-4 Approximate Entrance Skin Radiation Dose for Examination of the Adult Pelvis with a 400-Speed Image Receptor
    • TABLE 11-5 Approximate Change in Radiographic Technique for Standard Grids
    • Grid Selection Factors
    • Air-Gap Technique
    • TABLE 11-6 Clinical Considerations in Grid Selection
    • Summary
    • FIGURE 11-33 Increasing the source-to-image receptor distance (SID) to 300 cm from 180 cm improves spatial resolution with no increase in patient dose.
    • Challenge Questions
    • Chapter 12 Screen-Film Radiography
    • Objectives
    • Radiographic Film
    • Base
    • FIGURE 12-1 Cross section of radiographic film. The bulk of the film is the base. The emulsion contains the latent image, which becomes visible when processed.
    • Emulsion
    • FIGURE 12-2 An example of a tabular silver halide crystal. The arrangement of atoms in the crystal is cubic.
    • TABLE 12-1 Types of Film Used in Medical Imaging
    • Silver Halide Crystal Formation
    • TABLE 12-2 Standard Film Sizes
    • Types of Film
    • Screen-Film
    • Contrast
    • Speed
    • FIGURE 12-3 A, Conventional silver halide crystals are irregular in size. B, New technology produces flat, tablet-like grains. C, Cubic grains.
    • Crossover
    • FIGURE 12-4 Crossover occurs when screen light crosses the base to expose the opposite emulsion.
    • FIGURE 12-5 Crossover is reduced by adding a dye to the base; this is called a crossover control layer.
    • Spectral Matching
    • FIGURE 12-6 Radiographic films are blue sensitive or green sensitive, and they require amber- and red-filtered safelights, respectively.
    • Reciprocity Law
    • Reciprocity Law
    • TABLE 12-3 Approximate Reciprocity Law Failure
    • Safelights
    • Direct-Exposure Film
    • Mammography Film
    • Handling and Storage of Film
    • Heat and Humidity
    • Light
    • Radiation
    • Formation of the Latent Image
    • FIGURE 12-7 Silver halide crystal lattice contains ions. Electrons from Ag atoms have been loaned to Br and I atoms.
    • Silver Halide Crystal
    • Photon Interaction with Silver Halide Crystal
    • FIGURE 12-8 Model of a silver halide crystal emphasizing the sensitivity center and the concentration of negative ions on the surface.
    • FIGURE 12-9 Production of the latent image and conversion of the latent image into a visible image require several steps. A, Light photon interaction releases electrons. B, These electrons migrate to the sensitivity center. C, At the sensitivity center, atomic silver is formed by attraction of an interstitial silver ion. D, This process is repeated many times, resulting in the buildup of silver atoms. E, The remaining silver halide is converted to silver during processing. F, The silver grain results.
    • Secondary Electron Formation
    • Metallic Silver Formation
    • Latent Image
    • Radiographic Intensifying Screen Construction
    • FIGURE 12-10 Cross-sectional view of an intensifying screen, showing its four principal layers.
    • Protective Coating
    • Phosphor
    • Box 12-1 Favorable Properties of a Radiographic Intensifying Screen Phosphor
    • Reflective Layer
    • Base
    • FIGURE 12-11 A, Screen without reflective layer. B, Screen with reflective layer. Screens without reflective layers are not as efficient as those with reflective layers because fewer light photons reach the film.
    • FIGURE 12-12 Luminescence occurs when an outer-shell electron is raised to an excited state and returns to its normal state with the emission of a light photon.
    • Screen Characteristics
    • TABLE 12-4 Characteristics of Typical Radiographic Intensifying Screens
    • Box 12-2 Properties of Radiographic Intensifying Screens That Are Not Controlled by the Radiologic Technologist
    • Screen Speed
    • Intensification Factor
    • Radiation Quality
    • Image Processing
    • FIGURE 12-13 Graph showing approximate variation of the intensification factor (IF) with kVp.
    • Temperature
    • Image Noise
    • FIGURE 12-14 Image noise increases with higher conversion efficiency (CE) but not with higher detective quantum efficiency (DQE).
    • FIGURE 12-15 Radiographs of an x-ray test pattern made with direct-exposure film (right) and a par-speed screen-film combination (left). The difference in image blur is obvious.
    • Spatial Resolution
    • FIGURE 12-16 A, Reduction in spatial resolution is greater when the phosphor layers are thick. B, Reduction also is greater when the crystal size is large. These same conditions increase screen speed and reduce patient dose by producing a greater number of light photons per incident x-ray.
    • Screen-Film Combinations
    • FIGURE 12-17 Cross-sectional view of cassette containing front and back screens and loaded with double-emulsion film.
    • Cassette
    • Box 12-3 Advantages of Proper Screen-Film Use
    • Increased
    • Decreased
    • Carbon Fiber
    • Screen-Film Radiographic Exposure
    • FIGURE 12-18 Importance of spectral matching is demonstrated by showing the relative emission spectrum for a radiographic intensifying screen and the relative sensitivity of radiograph film to light from that screen.
    • Rare Earth Screens
    • TABLE 12-5 Composition and Emulsion of Radiographic Intensifying Screens
    • Higher X-ray Absorption
    • TABLE 12-6 Atomic Number and K-Shell Electron Binding Energy of High-Z Elements in Radiographic Intensifying Screen Phosphors
    • FIGURE 12-19 Probability of x-ray absorption in a calcium tungstate screen as a function of the incident x-ray energy.
    • FIGURE 12-20 X-ray absorption probability in a rare earth screen compared with that in a calcium tungstate screen. In the energy interval between respective K-shell electron binding energies, absorption in a rare earth screen is greater.
    • Higher Conversion Efficiency
    • FIGURE 12-21 X-ray absorption for three intensifying screen phosphors.
    • Spectrum Matching
    • FIGURE 12-22 Calcium tungstate emits a broad spectrum of light centered in the blue region. With rare earth screens, discrete emissions are centered near the green-yellow region.
    • FIGURE 12-23 Blue-sensitive film must be used with blue-emitting screens and green-sensitive film with green-emitting screens.
    • Safelights
    • Care of Screens
    • Film Processing
    • FIGURE 12-24 Radiographs of wire mesh are used to check for screen-film contact. A, Good contact is evident.
    • B, A warped cassette cover leads to a region of poor contact.
    • FIGURE 12-25 The first automatic processor, circa 1942.
    • FIGURE 12-26 The first roller transport automatic processor, circa 1956.
    • TABLE 12-7 Sequence of Events in Processing a Radiograph
    • Processing Chemistry
    • TABLE 12-8 Components of the Developer and Their Functions
    • Wetting
    • Development
    • Reduction to Metallic Silver
    • FIGURE 12-27 Development is the chemical process that amplifies the latent image. Only crystals that contain a latent image are reduced to metallic silver by the addition of developing agents.
    • FIGURE 12-28 The shape of the characteristic curve is controlled by the developing agents. Phenidone controls the toe, and hydroquinone controls the shoulder.
    • FIGURE 12-29 Underdevelopment results in a dull radiograph because the crystals that contain a latent image have not been completely reduced. Overdevelopment produces a similar radiograph because of the partial reduction of unexposed crystals. Proper development results in maximum contrast.
    • Fixing
    • TABLE 12-9 Components of the Fixer and Their Functions
    • FIGURE 12-30 Converting the latent image to a visible image requires a three-step process.
    • Washing
    • Drying
    • Automatic Processing
    • Transport System
    • TABLE 12-10 Principal Components of an Automatic Processor
    • FIGURE 12-31 A cutaway view of an automatic processor. Major components are identified.
    • FIGURE 12-32 Place the short side of the film against the side rail of the feed tray and alternate films from one side to another.
    • FIGURE 12-33 A, Transport rollers positioned opposite each other. B, Transport rollers positioned offset from one another.
    • FIGURE 12-34 A master roller with planetary rollers and guide shoes is used to reverse the direction of film in a processor.
    • FIGURE 12-35 A transport rack subassembly.
    • Temperature Control System
    • Circulation System
    • Replenishment System
    • Dryer System
    • Summary
    • Challenge Questions
    • Chapter 13 Screen-Film Radiographic Technique
    • Objectives
    • Exposure Factors
    • Kilovolt Peak
    • Milliamperes
    • TABLE 13-1 Factors That May Influence X-ray Quantity and Quality
    • Ampere
    • Exposure Time
    • TABLE 13-2 Relationships Among Different Units of Exposure Time
    • mAs
    • Equivalent Exposures of Equal mAs
    • Total Projectile Electrons
    • TABLE 13-3 Products of Milliampere (mA) and Time (ms) for 10 mAs
    • Distance
    • The Direct Square Law
    • Imaging System Characteristics
    • Focal-Spot Size
    • Filtration
    • FIGURE 13-1 Examples of selectable added filtration.
    • High-Voltage Generation
    • FIGURE 13-2 An open collimator showing the light field mirror and multiple layers of filtration.
    • TABLE 13-4 Characteristics of the Various Types of High-Voltage Generators
    • Patient Factors
    • FIGURE 13-3 The four general states of body habitus.
    • Thickness
    • TABLE 13-5 Fixed Kilovolt Peak Technique for an Anteroposterior Abdominal Examination
    • TABLE 13-6 Variable Kilovolt Peak Technique for an Anteroposterior Pelvis Examination
    • Composition
    • Pathology
    • FIGURE 13-4 Relative radiolucency and optical density (OD) are shown on this radiograph.
    • TABLE 13-7 Relative Degrees of Radiolucency
    • Box 13-1 Classifying Pathology
    • Image-Quality Factors
    • Optical Density
    • FIGURE 13-5 The amount of light transmitted through a radiograph is determined by the optical density (OD) of a film. The step-wedge radiograph shows a representative range of OD.
    • FIGURE 13-6 A, Overexposed radiograph of the chest is too black to be diagnostic. B, Likewise, an underexposed chest radiograph is unacceptable because no detail to the lung fields is apparent.
    • FIGURE 13-7 Normal chest radiograph taken at 100 cm source-to-image receptor distance (SID). B, If the exposure technique factors are not changed, a similar radiograph at 90 cm SID (A) will be overexposed, and at 180 cm SID (C), will be underexposed.
    • FIGURE 13-8 Optical density is determined principally by the mAs value, as shown by these phantom radiographs of the abdomen taken at 70 kVp. A, 10 mAs. B, Plus 25%, 12.5 mAs. C, Plus 50%, 15 mAs.
    • FIGURE 13-9 Changes in mAs value have a direct effect on optical density (OD). A, Original image. B, Decrease in OD when the mAs value is decreased by half. C, Increase in OD when the mAs value is doubled.
    • Contrast
    • FIGURE 13-10 Normal chest radiograph taken at 70 kVp (B). If the kilovoltage is increased by 15% to 80 kVp (A), overexposure occurs. Similarly, at 15% less, 60 kVp (C), the radiograph is underexposed.
    • TABLE 13-8 Technique Factors That May Affect Optical Density
    • FIGURE 13-11 Radiograph of the abdomen showing the vertebral column with its inherent high contrast. The kidneys, liver, and psoas muscle are low-contrast tissues that are visualized better with low kVp.
    • FIGURE 13-12 Radiographs of a pelvis phantom demonstrate a short scale of contrast (A) and a long scale of contrast (B).
    • FIGURE 13-13 Images of a step wedge exposed at low kVp (A) and at high kVp (B) illustrate the meaning of short scale and long scale of contrast, respectively.
    • FIGURE 13-14 Radiographs of the pelvis and abdomen show that a 4-kVp increase results in a perceptible change in contrast. A, 75 kVp and 28 mAs. B, 79 kVp and 28 mAs. C, 81 kVp and 28 mAs.
    • TABLE 13-9 Relationship Between Kilovolt Peak and Scale of Contrast
    • TABLE 13-10 Exposure Technique Factors That May Affect Radiographic Contrast*
    • FIGURE 13-15 A radiograph taken with a 1-mm focal-spot x-ray tube (A) exhibits far greater detail than one taken with a 2-mm focal-spot x-ray tube (B).
    • Detail
    • Distortion
    • FIGURE 13-16 Same radiograph as shown in 15-15, A, except that visibility of image detail is reduced because of safelight fog.
    • FIGURE 13-17 A, Normal projection of the scapula. B, Elongation of the scapula. C, Foreshortening of the scapula.
    • TABLE 13-11 Principal Radiographic Image-Quality Factors
    • Exposure Technique Charts
    • FIGURE 13-18 Radiographs of a knee phantom taken at 58 kVp. That obtained at 12 mAs (B) was selected to begin the variable-kilovoltage chart.
    • Variable kVp
    • TABLE 13-12 Variable Kilovolt Peak Chart for Examination of the Knee
    • Automatic Exposure Techniques
    • FIGURE 13-19 Radiographs of an abdomen phantom used to construct a fixed-kVp chart. All exposures were taken at 80 kVp. From this series, 80 mAs (B) was selected to begin the chart.
    • FIGURE 13-20 High-voltage chest radiograph illustrates improved visualization of mediastinal structures.
    • TABLE 13-13 Fixed-Kilovolt Peak Chart for Examination of the Abdomen
    • TABLE 13-14 Factors to Consider When Constructing an Exposure Chart for Automatic Systems
    • FIGURE 13-21 Vertical chest Bucky shows the position of automatic exposure control (AEC) sensors represented as three rectangles.
    • FIGURE 13-22 Anatomically programmed radiography (APR) operating console with lower ribs and automatic exposure control selected.
    • Tomography
    • FIGURE 13-23 This tomography system is designed for linear movement with a general-purpose imaging system.
    • FIGURE 13-24 A, Image receptor and tube head of a general-purpose x-ray imaging system designed to move tomographically within a plane. B, An imaging system designed for tomography to move within an arc.
    • TABLE 13-15 Representative Linear Tomography Techniques
    • FIGURE 13-25 Relationship of the fulcrum, object plane, and tomographic angle.
    • FIGURE 13-26 Only objects lying in the object plane are properly imaged. Objects above and below this plane are blurred because they are imaged across the film.
    • TABLE 13-16 Approximate Values for Section Thickness During Linear Tomography as a Function of Tomographic Angle
    • FIGURE 13-27 Section thickness is determined by the tomographic angle. A, A large tomographic angle results in a thin section. B, A small tomographic angle results in a thick section.
    • FIGURE 13-28 This test object image shows properly calibrated elevation and increased blur of objects perpendicular to the motion of the x-ray tube.
    • FIGURE 13-29 Foot tomographs obtained with x-ray tube motion. A, Parallel to the body axis. B, Perpendicular to the body axis.
    • FIGURE 13-30 X-ray source–image receptor motion for panoramic tomography.
    • Magnification Radiography
    • Magnification Factor
    • FIGURE 13-31 Panoramic tomogram showing restorations and a right mandibular defect.
    • FIGURE 13-32 Principle of magnification radiography. The magnification factor is equal to the ratio of image size to object size.
    • Summary
    • Challenge Questions

Part IV The Digital Radiographic Image

    • Chapter 14 Computers in Medical Imaging
    • Objectives
    • History of Computers
    • FIGURE 14-1 The abacus was the earliest calculating tool.
    • FIGURE 14-2 The ENIAC (Electronic Numerical Integrator And Calculator) computer occupied an entire room. It was completed in 1946 and is recognized as the first all-electronic, general-purpose digital computer.
    • FIGURE 14-3 This Celeron microprocessor incorporates more than 1 million transistors on a chip of silicon that measures less than 1 cm on a side.
    • FIGURE 14-4 Today’s personal computer has exceptional speed, capacity, and flexibility and is used for numerous applications in radiology.
    • Computer Architecture
    • FIGURE 14-5 A timeline showing the evolution of today’s computer.
    • FIGURE 14-6 Two styles of wristwatches demonstrate analog versus digital.
    • Computer Language
    • FIGURE 14-7 The origin of the decimal number system.
    • Binary Number System
    • TABLE 14-1 Organization of Binary Number System
    • TABLE 14-2 Power of Ten, Power of Two, and Binary Notation
    • Bits, Bytes, and Words
    • Computer Programs
    • Systems Software
    • Application Programs
    • FIGURE 14-8 The sequence of software manipulations required to complete an operation.
    • Hexadecimal Number System
    • FORTRAN
    • BASIC
    • TABLE 14-3 The Hexadecimal Number System
    • TABLE 14-4 Programming Languages
    • QuickBASIC
    • COBOL
    • Pascal
    • C, C++
    • Visual C++, Visual Basic
    • Macros
    • Components
    • FIGURE 14-9 The width of the conductive lines in this microprocessor chip is 1.5 µm.
    • FIGURE 14-10 The central processing unit (CPU) contains a control unit, an arithmetic unit, and sometimes memory.
    • FIGURE 14-11 The control unit is a part of the central processing unit (CPU) that is directly connected with additional primary memory and various input/output devices.
    • Memory
    • Storage
    • FIGURE 14-12 Compact disc.
    • FIGURE 14-13 A flash drive is a small, solid-state device that is capable of storing in excess of 1 TB of data.
    • FIGURE 14-14 This disc drive reads all formats of optical compact discs and reads, erases, writes, and rewrites to a 650-MB optical cartridge.
    • Output Devices
    • FIGURE 14-15 This 1946 Wurlitzer jukebox with its 78-rpm platters serves as a model for the optical disc jukebox of the picture archiving and communication system (PACS) network.
    • Communications
    • FIGURE 14-16 The capacity and speed of computers has soared since 1990.
    • Input
    • Applications to Medical Imaging
    • Summary
    • Challenge Questions
    • Chapter 15 Computed Radiography
    • Objectives
    • Computed Radiography Terms
    • The Computed Radiography Image Receptor
    • FIGURE 15-1 Sequence of activity for screen-film radiography.
    • Photostimulable Luminescence
    • FIGURE 15-2 X-ray interaction with a photostimulable phosphor results in excitation of electrons into a metastable state.
    • FIGURE 15-3 When metastable electrons return to their ground state, visible light is emitted.
    • FIGURE 15-4 Cross section of a photostimulable phosphor (PSP) screen.
    • Imaging Plate
    • FIGURE 15-5 Some storage phosphor screens (SPSs) incorporate phosphors grown as linear filaments that increase the absorption of x-rays and limit the spread of stimulated emission.
    • FIGURE 15-6 Computed radiography imaging plate prepared for insertion into electronic reader.
    • Light Stimulation–Emission
    • FIGURE 15-7 Expose: The first of a sequence of events that results in an x-ray–induced image-forming signal.
    • FIGURE 15-8 Stimulate: Stimulation of the latent image results from the interaction of an infrared laser beam with the photostimulable phosphor (PSP).
    • FIGURE 15-9 Read: The light signal emitted after stimulation is detected and measured.
    • FIGURE 15-10 Erase: Before reuse, any residual metastable electrons are moved to the ground state by an intense light.
    • FIGURE 15-11 The laser light used to stimulate the photostimulable phosphor is monochromatic. Resultant emitted light is polychromatic.
    • FIGURE 15-12 The computed radiography reader is a compact mechanical, optical, computer assembly.
    • The Computed Radiography Reader
    • Mechanical Features
    • Optical Features
    • FIGURE 15-13 The drive mechanisms of the computed radiography (CR) reader move the imaging plate (IP) slowly along its long axis, while an oscillating beam deflection mirror causes the stimulating laser beam to sweep rapidly across the IP.
    • FIGURE 15-14 The optical components and optical path of a computed radiography (CR) reader are highlighted.
    • Computer Control
    • FIGURE 15-15 The computer complement to a computed radiography (CR) reader provides signal amplification, signal compression, scanning control, analog-to-digital conversion, and image buffering.
    • Imaging Characteristics
    • FIGURE 15-16 The image receptor response for computed radiography (CR) is shown with the characteristic curve of a screen-film image receptor.
    • Image Receptor Response Function
    • FIGURE 15-17 Improper radiographic technique with a screen-film image receptor results in an unacceptable image.
    • FIGURE 15-18 Computed radiography (CR) images obtained through the same radiographic technique used in Figure 15-17.
    • Image Noise
    • Box 15-1 Sources of Image Noise in Screen-Film Radiography
    • Box 15-2 Sources of Image Noise in Computed Radiography
    • Patient Characteristics
    • Radiation Dose
    • FIGURE 15-19 This region of the image receptor response curve suggests that significant patient radiation dose reduction may be possible with computed radiography (CR).
    • Workload
    • Summary
    • FIGURE 15-20 The transition from screen-film radiography to computed radiography (CR) removes one step from the radiography workload process.
    • Challenge Questions
    • Chapter 16 Digital Radiography
    • Objectives
    • Scanned Projection Radiography
    • FIGURE 16-1 An organizational scheme for digital radiography.
    • FIGURE 16-2 A scanned projection radiograph is obtained in computed tomography by maintaining the energized x-ray tube–detector array fixed while the patient is translated through the gantry.
    • Charge-Coupled Device
    • FIGURE 16-3 A scanned projection radiograph of the entire trunk of the body obtained in computed tomography.
    • FIGURE 16-4 The components of a dedicated chest scanned projection radiography.
    • FIGURE 16-5 A tiled charge-coupled device (CCD) designed for digital radiography (DR) imaging.
    • FIGURE 16-6 The radiation response of a charge-coupled device (CCD) compared with that of a 400-speed screen-film image receptor.
    • Cesium Iodide/ Charge-Coupled Device
    • FIGURE 16-7 Charge-coupled devices (CCDs) can be tiled to receive the light from an area x-ray beam as it interacts with a scintillation phosphor such as cesium iodide (CsI).
    • FIGURE 16-8 A versatile CsI flat panel digital radiographic imaging system.
    • Cesium Iodide/Amorphous Silicon
    • FIGURE 16-9 The cesium iodide (CsI) phosphor in digital radiography image receptors is available in the form of filaments to improve x-ray absorption and reduce light dispersion.
    • FIGURE 16-10 Digital radiographic images can be produced from the cesium iodide (CsI) phosphor light detected by the active matrix array (AMA) of silicon photodiodes.
    • FIGURE 16-11 A photomicrograph of an active matrix array–thin-film transistor (AMA-TFT) digital radiography (DR) image receptor with a single pixel highlighted.
    • FIGURE 16-12 The fill factor is that portion of the pixel element that is occupied by the sensitive image receptor.
    • FIGURE 16-13 The use of amorphous selenium as an image receptor capture element eliminates the need for a scintillation phosphor.
    • Amorphous Selenium
    • Digital Mammography
    • FIGURE 16-14 The line spread function is largest for screen-film mammography and least for amorphous selenium (a-Se) digital mammography.
    • FIGURE 16-15 A digital mammographic imaging system based on amorphous selenium (a-Se) technology.
    • FIGURE 16-16 Secur View.
    • Summary
    • FIGURE 16-17 The projection scheme for digital mammography tomosynthesis.
    • FIGURE 16-18 A, One view of a mammogram versus (B) the same anatomy viewed by digital mammography tomosynthesis. (Courtesy Loretta Hanset, Harris County Hospital District.)
    • FIGURE 16-19 Several additional steps are eliminated when progressing from screen-film radiography through CR to DR.
    • Challenge Questions
    • Chapter 17 Digital Radiographic Technique
    • Objectives
    • Spatial Resolution
    • Spatial Frequency
    • FIGURE 17-1 Resolution in space is a measure of how small an object one can see on an image.
    • FIGURE 17-2 A line pair (lp) is a high-contrast line that is separated by an interspace of equal width.
    • FIGURE 17-3 The spatial frequency of each of the line pairs of Figure 17-2.
    • FIGURE 17-4 Three entrepreneurs and their working attire demonstrate the concept of spatial frequency.
    • Table 17-1 Approximate Spatial Resolution for Various Medical Imaging Systems
    • Modulation Transfer Function
    • FIGURE 17-5 When a line pair pattern is imaged, the higher spatial frequencies become blurred, resulting in reduced modulation.
    • FIGURE 17-6 These plastic-encased lead bar patterns are imaged to construct a modulation transfer function (MTF).
    • FIGURE 17-7 A plot of the modulation data from Figure 17-5 results in a modulation transfer function (MTF) curve.
    • FIGURE 17-8 Screen-film mammography has a higher modulation transfer function (MTF) at low spatial frequencies and higher spatial frequencies than screen-film radiography.
    • Contrast Resolution
    • FIGURE 17-9 These photographs illustrate differences in image appearance associated with the modulation transfer function (MTF) curves of (A) radiography and (B) mammography.
    • FIGURE 17-10 The modulation transfer function (MTF) curve for any digital radiographic imaging system is characterized by a cutoff frequency determined by pixel size. In this illustration, the cutoff frequency is 4 lp/mm, which corresponds to a 125-µm pixel size.
    • Dynamic Range
    • FIGURE 17-11 The contrast of a radiographic image can be somewhat controlled, but the visual range remains at approximately 30 shades of gray.
    • Postprocessing
    • FIGURE 17-12 Digital imaging systems have a dynamic range greater than four orders of magnitude.
    • Table 17-2 Dynamic Range of Digital Medical Imaging Systems
    • FIGURE 17-13 Although a 14-bit dynamic range contains 16,384 shades of gray, we can see only about 30 of them.
    • FIGURE 17-14 With the window and level postprocessing tool, any region and range of the 16,384 can be rendered as 30 shades of gray.
    • Signal-to-Noise Ratio
    • Contrast-Detail Curve
    • FIGURE 17-15 A, With screen-film mammography what you see is what you get. B, With digital mammography, contrast is enhanced. C and D, By postprocessing the digital image, contrast can be further enhanced.
    • FIGURE 17-16 Image-forming x-rays are those that are transmitted through the patient unattenuated (signal) and those that are Compton scattered (noise).
    • FIGURE 17-17 A contrast-detail test tool for constructing a contrast-detail curve.
    • FIGURE 17-18 A contrast-detail tool (A) and its image (B) allows construction of a contrast-detail curve.
    • FIGURE 17-19 The contrast-detail curve is a plot of minimum visual size as a function of contrast.
    • FIGURE 17-20 Contrast-detail curves for two different digital imaging systems with different pixel sizes.
    • FIGURE 17-21 Contrast-detail curves for a single digital imaging system operated at different mAs.
    • FIGURE 17-22 Contrast-detail curves for various medical imaging systems.
    • Patient Radiation Dose Considerations
    • FIGURE 17-23 Response of a screen-film and a digital image receptor. The emphasized range is that normally chosen for screen-film exposure. The digital radiography image receptor can receive essentially any radiation exposure.
    • Image Receptor Response
    • Detective Quantum Efficiency
    • Box 17-1 Dose Reduction with Digital Radiography
    • FIGURE 17-24 Screen-film radiographs of a foot phantom showing overexposure and underexposure because of wide-ranging technique.
    • FIGURE 17-25 Digital images of a foot phantom using the same radiographic techniques as in Figure 28-24 show the maintenance of contrast over a wide range of patient radiation doses.
    • FIGURE 17-26 At very low exposure of a digital image receptor, spatial resolution and contrast are maintained, but image noise may be troublesome.
    • Table 17-3 Atomic Number and K-Shell Binding Energy for Various Image Receptors
    • FIGURE 17-27 Detective quantum efficiency as a function of x-ray energy for various image receptor capture elements.
    • Summary
    • FIGURE 17-28 The x-ray beam incident on the image receptor is lower in energy than the beam incident on the patient and better matches the x-ray absorption of capture elements.
    • Challenge Questions
    • Chapter 18 Viewing the Digital Radiographic Image
    • Objectives
    • Photometric Quantities
    • Response of the Eye
    • Photometric Units
    • FIGURE 18-1 Photometric response curves for human vision.
    • TABLE 18-1 Photometric Quantities and Units
    • Cosine Law
    • FIGURE 18-2 When a digital display device is viewed from the side, illumination and image contrast are reduced.
    • TABLE 18-2 Illuminance in Modern Lighting
    • Hard Copy–soft Copy
    • FIGURE 18-3 Liquid crystals are randomly oriented in the natural state and are structured under the influence of an external electric field.
    • Active Matrix Liquid Crystal Display
    • Display Characteristics
    • Image Luminance
    • FIGURE 18-4 Cross-sectional rendering of one pixel of an active matrix liquid crystal display (AMLCD).
    • TABLE 18-3 Standard Sizes of Medical Flat Panel Digital Display Devices
    • TABLE 18-4 Principal Differences Between Cathode Ray Tube and Active Matrix Liquid Crystal Display Digital Display Devices
    • FIGURE 18-5 Loss of image contrast as a function of off-perpendicular viewing of an active matrix liquid crystal display (AMLCD).
    • Ambient Light
    • Preprocessing THE Digital Radiographic Image
    • FIGURE 18-6 An ergonomically designed digital image workstation.
    • TABLE 18-5 Digital Image Preprocessing
    • Postprocessing The Radiographic Digital Image
    • FIGURE 18-7 A, Exposure to a raw x-ray beam shows the heel effect on the image. B, Flatfielding corrects this defect and makes the image receptor response uniform. (Courtesy Anthony Siebert, University of California, Davis.)
    • TABLE 18-6 Digital Image Postprocessing
    • FIGURE 18-8 Digital image inversion is sometimes helpful in making disease more visible, as in this case of a digital hand image.
    • Picture Archiving and Communication System
    • Figure 18-9 A, A thin film digitizer uses a laser beam to convert an analog radiograph into a digital image. B, The printing to film is similar to that of a laser printer. (A courtesy Agfa; B courtesy Imation.)
    • Network
    • FIGURE 18-10 The picture archiving and communication system (PACS) network allows interaction among the various modes of data acquisition, image processing, and image archiving.
    • Storage System
    • Summary
    • TABLE 18-7 Approximate Digital File Size for Various Medical Images
    • Challenge Questions
    • FIGURE 18-11 Combining digital images with a Picture Archiving and Communication System (PACS) network eliminates even more steps in medical imaging workflow and enhances efficiency.

Part V Image Artifacts and Quality Control

    • Chapter 19 Screen-Film Radiographic Artifacts
    • Objectives
    • Exposure Artifacts
    • FIGURE 19-1 Screen-film radiography. Artifact classification.
    • FIGURE 19-2 A, Lateral cervical spine of a patient with a “Black Eyed Peas starter set.” B, The patient’s glasses were not removed from the shirt pocket. C, The ice bag under the neck was not removed during this anteroposterior (AP) cervical spine view. D, This Waters view was properly coned, but the bifocals, earrings, and dental apparatus should have been removed.
    • TABLE 19-1 Common Exposure Artifacts
    • Processing Artifacts
    • Roller Marks
    • TABLE 19-2 Common Processing Artifacts
    • Dirty Rollers
    • FIGURE 19-3 Guide shoe marks left by an improperly serviced turnaround assembly.
    • FIGURE 19-4 Pi line artifacts caused by lack of processor cleaning.
    • Chemical Fog
    • Wet-Pressure Sensitization
    • FIGURE 19-5 Excess chemistry runs down the leading edge of the film, creating a dichroic stain “curtain” effect.
    • FIGURE 19-6 Wet-pressure sensitization caused by a dirty processor.
    • Handling and Storage Artifacts
    • TABLE 19-3 Common Handling and Storage Artifacts
    • Light or Radiation Fog
    • FIGURE 19-7 Preprocessing pressure artifacts can appear as scratches caused by heavy finger pressure on the feed tray and as “fingernail” marks caused by kinking of the film. A, Scratches. B, “Fingernail” marks.
    • Pressure or Kink Marks
    • Static
    • Hypo Retention
    • Summary
    • FIGURE 19-8 A, Tree static. B, Smudge static. These are the two most common types of static artifacts.
    • Challenge Questions
    • Chapter 20 Screen-Film Radiographic Quality Control
    • Objectives
    • Quality Assurance
    • Box 20-1 The Joint Commission’s 10-Step Quality Assurance Program
    • Quality Control
    • TABLE 20-1 Characteristics of Various Diagnostic Imaging Systems
    • Screen-Film Radiographic Quality Control
    • Filtration
    • FIGURE 20-1 Medical physicist preparing for quality control (QC) measurements.
    • TABLE 20-2 Elements of a Quality Control Program for Radiographic Systems
    • Collimation
    • Focal-Spot Size
    • TABLE 20-3 Minimum Half-Value Layer Required to Ensure Adequate X-ray Beam Filtration
    • FIGURE 20-2 A test tool for monitoring the coincidence of the x-ray beam and light field.
    • FIGURE 20-3 The pinhole camera, star pattern, and slit camera may be used to measure focal-spot size.
    • FIGURE 20-4 A line-pair test pattern. Its radiographic image measures limiting spatial resolution rather than focal-spot size.
    • Kilovolt Peak Calibration
    • FIGURE 20-5 High-voltage (kVp) and other generator functions can be evaluated with compact test devices.
    • Exposure Timer Accuracy
    • FIGURE 20-6 Device for measuring the accuracy of an exposure timer.
    • Exposure Linearity
    • TABLE 20-4 Exposure Time and mA Combinations Equal to 10 mAs
    • Exposure Reproducibility
    • Radiographic Intensifying Screens
    • Protective Apparel
    • Film Illuminators
    • FIGURE 20-7 Radiographs of mistreated protective aprons showing bunching of the lead (A) from folding and tearing, a low-density area in a new apron (B), and cracking patterns in an apron (C).
    • FIGURE 20-8 Measuring the luminance of a cathode ray tube screen with a photometer.
    • Tomography Quality Control
    • Processor Quality Control
    • TABLE 20-5 Exposure Technique and Entrance Skin Exposure During Conventional Tomographic Examination
    • FIGURE 20-9 Images of a pinhole in a lead attenuator during linear tomography. The larger pinhole image shows modest staggering motion, resulting in varied optical density.
    • Processor Cleaning
    • TABLE 20-6 Quality Control Program for Radiographic Film Processor
    • FIGURE 20-10 Automatic processor.
    • FIGURE 20-11 An automatic processor disassembled for cleaning.
    • Processor Maintenance
    • Processor Monitoring
    • Summary
    • Challenge Questions
    • Chapter 21 Digital Radiographic Artifacts
    • Objectives
    • Image Receptor Artifacts
    • FIGURE 21-1 Classification scheme for digital radiographic image artifacts.
    • FIGURE 21-2 Debris on image receptor in digital radiography can be confused with foreign bodies.
    • FIGURE 21-3 Residual glue on a computed radiography imaging plate resulted in this artifact, causing the plate to be removed from service.
    • FIGURE 21-4 Form for routine documentation of imaging plate performance to help reduce artifacts.
    • FIGURE 21-5 Look closely and you can see the pelvis at the top of this image and the bowel pattern at the bottom. This resulted because the imaging plate was not fully erased before the chest examination was performed.
    • Software Artifacts
    • Preprocessing
    • FIGURE 21-6 A, Note the white shapes on the left side, which resulted when the computed radiography (CR) imaging plate came apart. B, This is the CR plate, which shows corner damage and peeling.
    • FIGURE 21-7 Failure of electronic preprocessing can cause uninterpretable images in digital radiography.
    • Image Compression
    • FIGURE 21-8 A, An image receptor exposed to a raw x-ray beam may show a heel-effect response. B, Flatfielding preprocessing can make the response uniform. (Courtesy Charles Willis, M.D. Anderson Cancer Center.)
    • FIGURE 21-9 This image was produced by background radiation on a computed radiography plate that had not been used for days.
    • TABLE 21-1 Approximate Digital File Sizes for Various Imaging Modalities
    • Object Artifacts
    • Image Histogram
    • FIGURE 21-10 This histogram is a plot of the number of penguins as a function of the height of each penguin.
    • FIGURE 21-11 A, Simulated chest radiograph shows areas of lung and tissue that are unexposed (collimated) or fully exposed (raw x-ray beam). B, The point where each would fall on a characteristic curve.
    • Collimation and Partition
    • FIGURE 21-12 A, Region of a simulated digital chest radiograph. B, The corresponding image histogram. C, The placement of each region in A on the response curve of the digital image receptor.
    • FIGURE 21-13 Characteristic histograms for cervical spine, abdomen, and knee.
    • Box 21-1 Standard Digital Radiography Image Receptor Sizes
    • FIGURE 21-14 Underexposure in digital radiography causes loss of contrast in dense anatomy because of increased noise.
    • Alignment
    • FIGURE 21-15 A sampling of histogram analysis errors.
    • FIGURE 21-16 The blacked-out spine on this anteroposterior view was restored by engaging the automatic collimation feature. The white out on the patient’s left side was fixed by postconing that area and then engaging the “collimated image.”
    • Challenge Questions
    • FIGURE 21-17 Loss of contrast is obvious when three on one versus two on one imaging is compared.
    • FIGURE 21-18 If all four wrist images have the same signal intensity, the radiographer changed technique appropriately. Technique was not properly adjusted for the oblique view in the lower right region.
    • FIGURE 21-19 Two computed radiography plates used for spine imaging were placed into the processor in the wrong order.
    • FIGURE 21-20 Improperly collimated multiple fields not aligned with the imaging plate edge result in overexposure and the artifact seen here.
    • Chapter 22 Digital Radiographic Quality Control
    • Objectives
    • Performance Assessment Standards
    • SMPTE
    • NEMA-DICOM
    • DIN 2001
    • FIGURE 22-1 The SMPTE pattern was developed by the Society of Motion Picture and Television Engineers.
    • VESA
    • AAPM TG 18
    • Luminance Meter
    • FIGURE 22-2 Use of a near-range photometer during digital display device evaluation.
    • Digital Display Device Quality Control
    • Geometric Distortion
    • FIGURE 22-3 TG 18-QC test pattern.
    • Reflection
    • Luminance Response
    • FIGURE 22-4 Diffuse and specular reflections are illustrated for a color (left) and a monochrome (right) display device with the power off. Monochrome has reduced specular reflection caused by an improved antireflective coating.
    • FIGURE 22-5 TG 18-AD pattern used for evaluating diffuse reflection.
    • FIGURE 22-6 TG 18-CT pattern with half-16 area of half-moon targets.
    • FIGURE 22-7 Examples of different luminance patches for measurement of luminance response of the system, using AAPM TG 18-LN Test patterns.
    • FIGURE 22-8 TG 18-UN and TG 18-UNL patterns for luminance uniformity assessment.
    • FIGURE 22-9 TG 18-CX pattern for display resolution evaluation.
    • Display Resolution
    • Display Noise
    • FIGURE 22-10 TG 18-PX pattern for resolution uniformity evaluation.
    • FIGURE 22-11 TG 18-AFC pattern used to assess display noise.
    • FIGURE 22-12 TG 18-CH anatomic image for display evaluation.
    • Quality Control by the Technologist
    • Summary
    • Challenge Questions

Part VI Advanced X-Ray Imaging

    • Chapter 23 Mammography
    • Objectives
    • Soft Tissue Radiography
    • Basis for Mammography
    • Risk of Breast Cancer
    • Box 23-1 Risk Factors for Breast Cancer
    • Types of Mammography
    • TABLE 23-1 Recommended Intervals for Breast Examination
    • Breast Anatomy
    • FIGURE 23-1 Breast architecture determines the requirements for x-ray imaging systems and image receptors.
    • FIGURE 23-2 Approximate incidence of breast cancer by location within the breast.
    • The Mammographic Imaging System
    • TABLE 23-2 Features of a Dedicated Mammography System for Use with Screen Film
    • High-Voltage Generation
    • Target Composition
    • FIGURE 23-3 Representative dedicated mammography imaging systems. A, General Electric Senograph. B, Siemens Mammomat.
    • FIGURE 23-4 X-ray emission spectrum for a tungsten target x-ray tube with a 0.5-mm Al filter operated at 30 kVp.
    • FIGURE 23-5 X-ray emission spectrum for a molybdenum target x-ray tube with a 30-µm Mo filter operated at 26 kVp.
    • Focal-Spot Size
    • FIGURE 23-6 X-ray emission spectrum for a rhodium target x-ray tube with a 50-µm Rh filter operated at 28 kVp.
    • TABLE 23-3 Mammographic Technique Chart
    • FIGURE 23-7 Pinhole camera images of (A) the circular focal spot of a mammography x-ray tube and (B) a double banana–shaped focal spot from a general purpose x-ray tube.
    • FIGURE 23-8 When the x-ray tube is tilted in its housing, the effective focal spot is small, the x-ray intensity is more uniform, and tissue against the chest wall is imaged.
    • Filtration
    • FIGURE 23-9 Emission spectrum from a tungsten target x-ray tube filtered by molybdenum and rhodium.
    • Heel Effect
    • FIGURE 23-10 A, Unfiltered molybdenum x-ray emission spectrum. B, The probability of x-ray absorption in molybdenum. C, Bremsstrahlung x-rays are suppressed and characteristic x-ray emission becomes prominent when a molybdenum target is filtered with molybdenum.
    • Compression
    • FIGURE 23-11 The heel effect can be used to advantage in mammography by positioning the cathode toward the chest wall to produce a more uniform optical density.
    • FIGURE 23-12 Compression in mammography has three principal advantages: improved spatial resolution, improved contrast resolution, and lower patient dose.
    • TABLE 23-4 Advantages of Vigorous Compression
    • Grids
    • Automatic Exposure Control
    • FIGURE 23-13 A high-transmission cellular grid designed specifically for mammography.
    • FIGURE 23-14 The relative position of the automatic exposure control device.
    • Magnification Mammography
    • Screen-Film Mammography
    • FIGURE 23-15 Photomicrograph of cubic grains in mammography film emulsions; the grains are 0.5 to 0.9 µm to produce higher contrast.
    • FIGURE 23-16 The correct way to load mammography film and position the cassette. Spatial resolution improves when the x-ray film is placed closest to the breast and between the x-ray tube and the radiographic intensifying screen.
    • Digital Mammography
    • Summary
    • Challenge Questions
    • Chapter 24 Mammography Quality Control
    • Objectives
    • Quality Control Team
    • Radiologist
    • FIGURE 24-1 The three members of the mammography quality control team.
    • Medical Physicist
    • Box 24-1 Annual Quality Control Evaluation to Be Performed by the Medical Physicist
    • Mammographer
    • Screen-Film Quality Control
    • TABLE 24-1 Elements of a Screen-film Mammographic Quality Control Program
    • Daily Tasks
    • Darkroom Cleanliness
    • FIGURE 24-2 These specks were produced by flakes trapped between the film and the screen.
    • Processor Quality Control
    • Weekly Tasks
    • Screen Cleanliness
    • FIGURE 24-3 Sheet of control film exposed with a sensitometer.
    • Viewboxes and Viewing Conditions
    • FIGURE 24-4 An example of the type of processor quality control record that should be maintained for each processor.
    • FIGURE 24-5 The proper way to dry screens after cleaning is to position them vertically.
    • FIGURE 24-6 Screen-film mammograms must be masked for proper viewing.
    • Test Object Images
    • FIGURE 24-7 Analysis of an image of the American College of Radiology mammography test object by a medical physicist scores the detection limits of the system for fibrils, microcalcifications, and nodules.
    • FIGURE 24-8 A test object image control chart.
    • FIGURE 24-9 A, The American College of Radiology accreditation test object. B, Its image.
    • FIGURE 24-10 These really gross artifacts are caused by processor rollers that have not been cleaned.
    • Monthly Tasks
    • Visual Checklist
    • FIGURE 24-11 This checklist contains items that mammographers should inspect monthly.
    • Quarterly Tasks
    • Repeat Analysis
    • Repeat Analysis
    • Analysis of Fixer Retention in Film
    • Semiannual Tasks
    • Darkroom Fog
    • Screen-Film Contact
    • FIGURE 24-12 Examination repeat analysis form.
    • FIGURE 24-13 Analysis to determine the amount of fixer retained on the film.
    • FIGURE 24-14 Wire mesh test tool for evaluating mammographic screen-film contact.
    • Compression
    • FIGURE 24-15 Images of a high-frequency wire mesh phantom showing (A) good and (B) poor screen-film contact.
    • FIGURE 24-16 Testing breast compression with a conventional bathroom scale.
    • Nonroutine Tasks
    • Film Crossover
    • Digital Quality Control
    • TABLE 24-2 Elements of a Digital Mammographic Quality Control Program
    • Summary
    • Challenge Questions
    • Chapter 25 Fluoroscopy
    • Objectives
    • An Overview
    • Special Demands of Fluoroscopy
    • Illumination
    • Human Vision
    • FIGURE 25-1 A fluoroscope and its associated parts.
    • FIGURE 25-2 The range of human vision is wide; it covers four orders of intensity magnitude.
    • FIGURE 25-3 The appearance of the human eye and the parts responsible for vision on a magnetic resonance image.
    • Fluoroscopic Technique
    • FIGURE 25-4 Red goggles were used to dark adapt for conventional screen fluoroscopy. This radiologist is back to the future.
    • Image Intensification
    • Image-Intensifier Tube
    • FIGURE 25-5 The image-intensifier tube converts the pattern of the x-ray beam into a bright visible-light image.
    • TABLE 25-1 Representative Fluoroscopic and Spot-Film Kilovolt Peak for Common Examinations
    • FIGURE 25-6 Cesium iodide crystals are grown as linear filaments and are packed tightly, as shown in these photomicrographs. A, Cross section. B, Face.
    • FIGURE 25-7 In an image-intensifier tube, each incident x-ray that interacts with the input phosphor results in a large number of light photons at the output phosphor. The image intensifier shown here has a flux gain of 3000.
    • Flux Gain
    • Brightness Gain
    • Minification Gain
    • Conversion Factor
    • FIGURE 25-8 Possible modes of operation with an image-intensifier tube. CCD, charge-coupled device.
    • Multifield Image Intensification
    • Magnification Mode Results In
    • FIGURE 25-9 Veiling glare reduces the contrast of an image-intensifier tube.
    • Fluoroscopic Image Monitoring
    • Television Monitoring
    • FIGURE 25-10 A 25/17/12 image-intensifier tube produces a highly magnified image in 12-cm mode.
    • FIGURE 25-11 These three variations of a vidicon television camera tube have a diameter of approximately 2.5 cm and a length of 15 cm. The right tube uses electrostatic rather than electromagnetic electron beam deflection.
    • FIGURE 25-12 Vidicon television camera tube and its principal parts.
    • Television Camera
    • Coupling to the Image Intensifier
    • FIGURE 25-13 The target of a television camera tube conducts electrons, creating a video signal only when illuminated.
    • FIGURE 25-14 Television camera tubes and charge-coupled devices (CCDs) are coupled to an image-intensifier tube in two ways. A, Fiberoptics. B, Lens system.
    • Television Monitor
    • FIGURE 25-15 A television picture tube (cathode ray tube [CRT]) and its principal parts.
    • Television Image
    • FIGURE 25-16 A video frame is formed from a raster pattern of two interlaced video fields.
    • Image Recording
    • FIGURE 25-17 The cassette-loaded spot film is positioned between the patient and the image intensifier.
    • Fluoroscopy Quality Control
    • TABLE 25-2 Cassette Spot Versus Photospot
    • TABLE 25-3 Entrance Skin Dose With Cassette-Loaded Spot Film
    • Exposure Rate
    • Spot-Film Exposures
    • TABLE 25-4 Entrance Skin Dose With Photofluorospot Imagers
    • Automatic Exposure Systems
    • Summary
    • FIGURE 25-18 American College of Radiology radiologic/fluoroscopic accreditation test objects.
    • Challenge Questions
    • Chapter 26 Digital Fluoroscopy
    • Objectives
    • DF Pixel Size
    • Digital Fluoroscopy Imaging System
    • FIGURE 26-1 The imaging chain in conventional fluoroscopy.
    • FIGURE 26-2 The components of a digital fluoroscopy system.
    • FIGURE 26-3 An installed remotely controlled digital fluoroscopic system with an over-table tube and under-table image receptor.
    • FIGURE 26-4 Operating console for a digital fluoroscopy system.
    • FIGURE 26-5 Pulse-progressive fluoroscopy involves terms such as duty cycle, interrogation time, and extinction time.
    • Image Receptor
    • Charge-Coupled Device
    • FIGURE 26-6 This charge-coupled device consists of 14-µm pixels arrayed in a 2048 × 2048 matrix; it views the light output of an image-intensifier tube.
    • FIGURE 26-7 Cross-sectional view of a charge-coupled device.
    • FIGURE 26-8 Manner in which a charge-coupled device can be coupled to the image-intensifier tube.
    • FIGURE 26-9 An example of a lens-coupling system for a charge-coupled device (CCD) to an image intensifier.
    • Box 26-1 Advantages of Charge-Coupled Devices for Medical Imaging
    • FIGURE 26-10 The response to light of a charge-coupled device is linear and can be electronically manipulated.
    • Flat Panel Image Receptor
    • FIGURE 26-11 A digital fluoroscope equipped with a flat panel image receptor.
    • Box 26-2 Advantages of Flat Panel Image Receptors Over Charge-Coupled Device Image Intensifiers in Digital Fluoroscopy
    • FIGURE 26-12 Flat panel image receptor (FPIR) fluoroscopy makes magnetic steering possible.
    • Image Display
    • Video System
    • Interlaced Versus Progressive Mode
    • Signal-to-Noise Ratio
    • FIGURE 26-13 The progressive mode of reading a video signal.
    • FIGURE 26-14 The information content of a video system with a high signal-to-noise ratio (SNR) is greatly enhanced. Shown here are a single video line through an object and the resultant signal at 200:1 and 1000:1 SNRs.
    • Flat Panel Image Display
    • Digital Subtraction Angiography
    • Image Formation
    • Temporal Subtraction
    • Mask Mode
    • Table 26-1 Comparison of Temporal and Energy Subtraction
    • FIGURE 26-15 A schematic representation of mask-mode digital fluoroscopy.
    • Remasking
    • Time-Interval Difference Mode
    • FIGURE 26-16 A, The preinjection mask. B, A postinjection image. C, Image produced when the preinjection mask is subtracted from the postinjection image.
    • FIGURE 26-17 The manner in which sequentially obtained images is subtracted in a time-interval difference study.
    • Misregistration
    • Energy Subtraction
    • FIGURE 26-18 Digital subtraction angiography (DSA) of the aorta–iliac area reveals the details of anomalies in the anastomosis region.
    • FIGURE 26-19 Misregistration artifacts.
    • FIGURE 26-20 Photoelectric absorption in iodine, bone, and muscle.
    • Hybrid Subtraction
    • FIGURE 26-21 Hybrid subtraction involves temporal and energy subtraction techniques.
    • FIGURE 26-22 A roadmapping neurovascular image.
    • Roadmapping
    • Table 26-2 Approximate Patient Radiation Dose in a Representative Fluoroscopic Examination
    • Patient Radiation Dose
    • Summary
    • Challenge Questions
    • Chapter 27 Interventional Radiology
    • Objectives
    • Types of Interventional Procedures
    • FIGURE 27-1 A radiologic technologist can specialize in many types of imaging modalities.
    • TABLE 27-1 Representative Procedures Conducted in an Interventional Radiology Suite
    • Basic Principles
    • Arterial Access
    • Guidewires
    • Catheters
    • FIGURE 27-2 Typical catheter shapes.
    • Contrast Media
    • Patient Preparation and Monitoring
    • FIGURE 27-3 Typical layout of an interventional radiology suite.
    • Risks of Arteriography
    • Interventional Radiology Suite
    • Personnel
    • Equipment
    • X-ray Tube
    • FIGURE 27-4 Advanced radiographic and fluoroscopic equipment.
    • TABLE 27-2 Specifications for a Typical Interventional Radiology X-ray Tube
    • FIGURE 27-5 For a given geometry such as this one, which produces a 0.2-mm focal-spot blur, the vessels must be twice the size of the focal-spot blur.
    • FIGURE 27-6 Typical interventional radiology patient couch with a floating, rotating, and tilting top.
    • High-Voltage Generator
    • Patient Couch
    • Image Receptor
    • Summary
    • Challenge Questions
    • Chapter 28 Computed Tomography
    • Objectives
    • FIGURE 28-1 Equipment arrangement for obtaining a radiograph, a conventional tomography, and a digital radiographic tomosynthesis image set.
    • Principles of Operation
    • FIGURE 28-2 Conventional tomography results in an image that is parallel to the long axis of the body. Computed tomography (CT) produces a transverse image.
    • Generations of Computed Tomography
    • FIGURE 28-3 In its simplest form, a computed tomography (CT) imaging system consists of a finely collimated x-ray beam and a single detector, both of which move synchronously in a translate and rotate fashion. Each sweep of the source detector assembly results in a projection, which represents the attenuation pattern of the patient profile.
    • FIGURE 28-4 Second-generation computed tomography imaging systems operated in the translate and rotate mode with a multiple detector array intercepting a fan-shaped x-ray beam.
    • FIGURE 28-5 Profiles of two x-ray beams used in computed tomography (CT) imaging. With the fan-shaped beam of second generation, a bow-tie filter is used to equalize the radiation intensity that reaches the detector array. For first-generation CT, a pencil x-ray beam is used.
    • FIGURE 28-6 Third-generation computed tomography imaging systems operate in the rotate-only mode with a fan x-ray beam and a multiple detector array revolving concentrically around the patient.
    • FIGURE 28-7 Ring artifacts can occur in third-generation computed tomography imaging systems because each detector views an annulus (ring) of anatomy during the examination. The malfunction of a single detector can result in the ring artifact.
    • FIGURE 28-8 Fourth-generation computed tomography imaging systems operate with a rotating x-ray source and stationary detectors.
    • Multislice Helical Computed Tomography Imaging Principles
    • FIGURE 28-9 Movement of the x-ray tube is not helical (A). It just appears that way because the patient moves through the plane of rotation during imaging (B).
    • FIGURE 28-10 Illustrating the difference between spiral and helical. We image with helical computed tomography.
    • FIGURE 28-11 Transverse images can be reconstructed at any plane along the z-axis.
    • FIGURE 28-12 Interpolation estimates a value between two known values. Extrapolation estimates a value beyond known values.
    • Interpolation Algorithms
    • Pitch
    • FIGURE 28-13 A, During multislice helical computed tomography, image data are continuously sampled. B, Interpolation of data is performed to reconstruct the image in any transverse plane.
    • Helical Pitch Ratio
    • Volume Imaging
    • Volume Imaging
    • TABLE 28-1 Tissue Imaged With Changing Pitch
    • TABLE 28-2 Tissue Imaged With Changing Pitch and a Gantry Rotation Time of 0.5 s
    • FIGURE 28-14 A 16-detector array, each array element 0.5 mm wide, collimated to an 8 mm beam width results in a pitch of 1.0.
    • FIGURE 28-15 Pitch is patient couch movement divided by x-ray beam width.
    • Sensitivity Profile
    • Imaging System Design
    • FIGURE 28-16 The section sensitivity profile (SSP) for a conventional computed tomography imaging system is nearly rectangular and is identified by its full width at half maximum (FWHM).
    • Operating Console
    • FIGURE 28-17 Components of a complete computed tomography imaging system.
    • FIGURE 28-18 Operator’s console for a multislice spiral computed tomography imaging system.
    • Physician’s Work Station
    • Computer
    • Gantry
    • X-ray Tube
    • FIGURE 28-19 This x-ray tube is designed especially for spiral computed tomography. It has a 15-cm-diameter disc that is 5 cm thick with an anode heat capacity of 7 MHU.
    • FIGURE 28-20 This multidetector array contains 64 rows of 1824 individual detectors, each 0.6 mm wide (116,736 detectors).
    • Detector Array
    • Collimation
    • FIGURE 28-21 Multislice helical computed tomography imaging systems incorporate both a prepatient collimator and a predetector collimator.
    • High-Voltage Generator
    • Patient Positioning and the Support Couch
    • Slip-Ring Technology
    • FIGURE 28-22 Slip rings and brushes electrically connect the components on the rotating gantry with the rest of the multislice helical computed tomography imaging system.
    • Image Characteristics
    • Image Matrix
    • FIGURE 28-23 The gantry of this multislice helical computed tomography imaging system contains a high-voltage generator, an x-ray tube, a detector array, and assorted control systems.
    • FIGURE 28-24 Each cell in a computed tomography image matrix is a two-dimensional representation (pixel) of a volume of tissue (voxel).
    • Pixel Size
    • Voxel Size
    • Computed Tomography Numbers
    • TABLE 28-3 Computed Tomography Number for Various Tissues and X-ray Linear Attenuation Coefficients at Four kVp Techniques
    • CT Numbers
    • Image Reconstruction
    • FIGURE 28-25 This four-pixel matrix demonstrates the method for reconstructing a computed tomography image by back projection.
    • Multiplanar Reformation
    • FIGURE 28-26 A maximum intensity projection reconstruction creates a three-dimensional image from multislice two-dimensional data sets. The result is a computed tomographic angiogram.
    • FIGURE 28-27 This carotid computed tomography (CT) scan was reconstructed from a 64-slice spiral CT examination.
    • Image Quality
    • FIGURE 28-28 Shaded surface image obtained during virtual colonoscopy reconstructed from a 64-slice spiral computed tomography data set.
    • FIGURE 28-29 Volume-rendering display of the heart obtained during cardiac computed tomography angiography (CCTA). This image can be rotated for three-dimensional visualization.
    • Spatial Resolution
    • FIGURE 28-30 Computed tomography (CT) examination of an object organ with distinct borders results in an image with somewhat blurred borders. The actual CT number profile of the object is abrupt, but that of the image is smoothed.
    • FIGURE 28-31 When a bar pattern of increasing spatial frequency is imaged, the fidelity of the image decreases. The tracing of image contrast reveals the loss of object information.
    • FIGURE 28-32 The modulation transfer function (MTF) is a plot of the image fidelity versus spatial frequency. The six data points plotted here are taken from the analysis of Figure 28-31.
    • FIGURE 28-33 Modulation transfer function (MTF) curves for two representative computed tomography imaging systems. Imaging system A has higher spatial resolution than imaging system B.
    • FIGURE 28-34 Imaging system A has better contrast resolution. Imaging system B has better spatial resolution.
    • Spatial Resolution/Spatial Frequency
    • Contrast Resolution
    • Noise
    • Noise
    • FIGURE 28-35 The phantom for evaluating computed tomography image quality contains test objects designed to measure spatial resolution (A), contrast resolution (B), linearity (C), and other image-quality factors (D).
    • FIGURE 28-36 No large differences are noted in mass density and effective atomic number among tissues, but the differences are greatly amplified by computed tomography imaging.
    • Linearity
    • Uniformity
    • FIGURE 28-37 A version of the five-pin test object designed by the American Association of Physicists in Medicine. The attenuation coefficient for each pin is known precisely, and the computed tomography number is computed.
    • FIGURE 28-38 Computed tomography (CT) linearity is acceptable if a graph of average CT number versus the linear attenuation coefficient is a straight line that passes through 0 for water.
    • TABLE 28-4 Characteristics of the Five-Pin American College of Radiology Accreditation Phantom
    • Imaging Technique
    • Multislice Detector Array
    • FIGURE 28-39 A four-slice helical computed tomography (CT) scan with a pitch of 2.0 covers eight times the tissue volume of single-slice helical CT.
    • FIGURE 28-40 A four-slice helical computed tomography scan allows changes to be made in slice thickness. A, Four slices of 0.5 mm each. B, Two 0.5-slices can be combined to make two 1-mm slices. C, Four 0.5-mm slices can be combined to make one 2-mm slice. DAS, data acquisition system.
    • Data Acquisition Rate
    • FIGURE 28-41 A dual-source multislice helical computed tomography imaging system.
    • Slice Acquisition Rate
    • Z-Axis Coverage
    • Z-Axis Coverage
    • Computed Tomography Quality Control
    • FIGURE 28-42 This computed tomography test object is used to evaluate noise spatial resolution, contrast resolution, slice thickness, linearity, and uniformity.
    • TABLE 28-5 Features of Multislice Helical Computed Tomography
    • Noise and Uniformity
    • Linearity
    • Spatial Resolution
    • Contrast Resolution
    • FIGURE 28-43 Schematic drawing (A) of a low-contrast computed tomography (CT) test object and (B) its image. This test object is designed especially for multislice helical CT.
    • Slice Thickness
    • Couch Incrementation
    • Laser Localizer
    • Patient Radiation Dose
    • Summary
    • FIGURE 28-44 Medical physics evaluation of computed tomography performance measurements using specially designed test objects.
    • Challenge Questions

Part VII Radiobiology

    • Chapter 29 Human Biology
    • Objectives
    • FIGURE 29-1 The sequence of events after radiation exposure of humans can lead to several radiation responses. At nearly every step, mechanisms for recovery and repair are available.
    • Human Radiation Response
    • Box 29-1 Human Responses to Ionizing Radiation
    • Deterministic Effects of Radiation on Humans
    • Stochastic Effects of Radiation on Humans
    • Effects of Fetal Irradiation
    • TABLE 29-1 Human Populations in Whom Radiation Effects Have Been Observed
    • Composition of the Body
    • Box 29-2 Atomic Composition of the Body
    • Cell Theory
    • Molecular Composition
    • Box 29-3 Molecular Composition of the Body
    • Water
    • Proteins
    • FIGURE 29-2 Proteins consist of amino acids linked by peptide bonds. The creation of the peptide bond requires the removal of a molecule of water.
    • Lipids
    • FIGURE 29-3 The structural configuration of a lipid is represented by a molecule of oleic acid: CH2(CH2)7CH = CH(CH2)7COOH.
    • Carbohydrates
    • Nucleic Acids
    • FIGURE 29-4 Carbohydrates are structurally different from lipids, even though their composition is similar. This is a molecule of sucrose, or ordinary table sugar: (C12H22O11).
    • FIGURE 29-5 DNA is the control center for life. A single molecule consists of a backbone of alternating sugar (deoxyribose) and phosphate molecules. One of the four organic bases is attached to each sugar molecule.
    • FIGURE 29-6 DNA consists of two long chains of alternating sugar and phosphate molecules fashioned similarly to the side rails of a ladder with pairs of bases as rungs.
    • The Human Cell
    • FIGURE 29-7 The DNA ladder is twisted about an imaginary axis to form a double helix.
    • FIGURE 29-8 Schematic view of a human cell shows the principal structural components.
    • Cell Function
    • FIGURE 29-9 Protein synthesis is a complex process that involves many different molecules and cellular structures.
    • Cell Proliferation
    • Mitosis
    • FIGURE 29-10 Progress of the cell through one cycle involves several phases.
    • FIGURE 29-11 During the synthesis portion of interphase, the chromosomes replicate from a two-chromatid structure (A) to a four-chromatid structure (B).
    • FIGURE 29-12 Mitosis is the phase of the cell cycle during which the chromosomes become visible, divide, and migrate to daughter cells. A, Interphase. B, Prophase. C, Metaphase. D, Anaphase. E, Telophase. F, Interphase.
    • FIGURE 29-13 Meiosis is the process of reduction division, and it occurs only in reproductive cells. n, Number of similar chromosomes.
    • Meiosis
    • Tissues and Organs
    • Box 29-4 Tissue Composition of the Body
    • Organ Systems
    • TABLE 29-2 Response to Radiation Is Related to Cell Type
    • TABLE 29-3 Relative Radiosensitivity of Tissues and Organs Based on Clinical Radiation Oncology
    • Summary
    • Challenge Questions
    • Chapter 30 Fundamental Principles of Radiobiology
    • Objectives
    • Box 30-1 Law of Bergonie and Tribondeau
    • Law of Bergonie and Tribondeau
    • Physical Factors that Affect Radiosensitivity
    • Linear Energy Transfer
    • Relative Biologic Effectiveness
    • Relative Biologic Effectiveness
    • FIGURE 30-1 As linear energy transfer (LET) increases, relative biologic effectiveness (RBE) also increases, but a maximum value is reached followed by a lower RBE because of overkill.
    • TABLE 30-1 Linear Energy Transfer and Relative Biologic Effectiveness of Various Radiation Doses
    • Protraction and Fractionation
    • Biologic Factors that Affect Radiosensitivity
    • Oxygen Effect
    • Oxygen Enhancement Ratio
    • FIGURE 30-2 The oxygen enhancement ratio (OER) is high for low linear energy transfer (LET) radiation and decreases in value as the LET increases.
    • Age
    • FIGURE 30-3 Radiosensitivity varies with age. Experiments with animals have shown that very young and very old individuals are more sensitive to radiation.
    • Recovery
    • Recovery
    • Chemical Agents
    • Radiosensitizers
    • Radioprotectors
    • Hormesis
    • Radiation Dose-Response Relationships
    • Linear Dose-Response Relationships
    • FIGURE 30-4 Linear dose-response relationships A and B are nonthreshold types; C and D are threshold types. RN is the normal incidence or response with no radiation exposure.
    • Nonlinear Dose-Response Relationships
    • FIGURE 30-5 Nonlinear dose-response relationships can assume several shapes. Curves A and B are nonthreshold. Curve C is nonlinear, threshold. DT, Threshold dose.
    • Constructing a Dose-Response Relationship
    • FIGURE 30-6 A dose-response relationship is produced when high-dose experimental data are extrapolated to low doses.
    • Summary
    • FIGURE 30-7 Dose-response relationship for radiation hormesis.
    • Challenge Questions
    • Chapter 31 Molecular Radiobiology
    • Objectives
    • FIGURE 31-1 The results of irradiation of macromolecules. A, Main-chain scission. B, Cross-linking. C, Point lesions.
    • Irradiation of Macromolecules
    • Main-Chain Scission
    • Cross-Linking
    • Point Lesions
    • Macromolecular Synthesis
    • FIGURE 31-2 The genetic code of DNA is transcribed by messenger RNA (mRNA) and is transferred to transfer RNA (tRNA), which translates it into a protein.
    • FIGURE 31-3 During S phase, the DNA separates like a zipper, and two daughter DNA molecules are formed, each alike and each a replicate of the parent molecule.
    • Radiation Effects on DNA
    • FIGURE 31-4 DNA is the target molecule for radiation damage. It forms chromosomes and controls cell and human growth and development.
    • FIGURE 31-5 Normal and radiation-damaged human chromosomes. A, Normal. B, Terminal deletion. C, Dicentric formation. D, Ring formation.
    • FIGURE 31-6 Types of damage that can occur in DNA. A, One side rail severed. B, Both side rails severed. C, Cross-linking. D, Rung breakage.
    • Radiation Response of DNA
    • Radiolysis of Water
    • FIGURE 31-7 A point mutation results in the change or loss of a base, which creates an abnormal gene. This is therefore a genetic mutation that is passed to one of the daughter cells.
    • FIGURE 31-8 The radiolysis of water results in the formation of ions and free radicals.
    • Ionization
    • Additional Ionization
    • Dissociation
    • Hydrogen Peroxide
    • Hydroperoxyl Formation
    • Hydrogen Peroxide Formation
    • Organic Free Radical Formation
    • Organic Free Radical Formation
    • Direct and Indirect Effects
    • Summary
    • Challenge Questions
    • Chapter 32 Cellular Radiobiology
    • Objectives
    • Target Theory
    • FIGURE 32-1 According to target theory, cell death will occur only if the target molecule is inactivated. DNA, the target molecule, is located within the cell nucleus.
    • FIGURE 32-2 In the presence of oxygen, the indirect effect is amplified, and the volume of action for low-linear energy transfer (LET) radiation is enlarged. The effective volume of action for high-LET radiation remains unchanged, in that maximum injury will have been inflicted by direct effect.
    • FIGURE 32-3 When single cells are planted in a Petri dish, they grow into visible colonies. Fewer colonies develop if the cells are irradiated.
    • Cell-Survival Kinetics
    • FIGURE 32-4 When rain falls on a dry pavement that consists of a large number of squares, the number of squares that remains dry decreases exponentially as the number of raindrops increases.
    • Single-Target, Single-Hit Model
    • FIGURE 32-5 When the number of dry squares is plotted on semilogarithmic paper as a function of the number of raindrops, a straight line results because when a few drops fall, some squares will be hit more than once.
    • FIGURE 32-6 After irradiation of 1000 cells, the dose-response relationship is exponential. The D37 is the dose that results in 37% survival.
    • Single-Target, Single-Hit Model
    • FIGURE 32-7 If each pavement square has two equal parts, each part must be hit for the square to be considered wet.
    • Multitarget, Single-Hit Model
    • FIGURE 32-8 When a square contains two equal parts, both of which have to be hit to be considered wet, three regions of the dry square versus raindrops relationship can be identified.
    • FIGURE 32-9 The multitarget, single-hit model of cell survival is characteristic of human cells that contain two targets.
    • Multitarget, Single-Hit Model
    • TABLE 32-1 Doses for Various Experimental Mammalian Cell Lines
    • Recovery
    • Cell-Cycle Effects
    • FIGURE 32-10 Split-dose irradiation results in a second cell survival curve with the same characteristics as the first and displaced along the dose axis by DQ.
    • FIGURE 32-11 The age response of human fibroblasts after irradiation shows minimum survival during the M phase and maximum survival during the late S phase. Such cells are most radiosensitive during mitosis and most radioresistant during the late S phase.
    • Linear Energy Transfer, Relative Biologic Effectiveness, and Oxygen Enhancement Ratio
    • FIGURE 32-12 Representative cell-survival curves after exposure to 200-kVp x-rays and 14-MeV neutrons.
    • Relative Biologic Effectiveness
    • FIGURE 32-13 Cell-survival curves for human cells irradiated in the presence and the absence of oxygen with high- and low-linear energy transfer (LET) radiation.
    • Oxygen Enhancement Ratio
    • Summary
    • Challenge Questions
    • Chapter 33 Deterministic Effects of Radiation
    • Objectives
    • Acute Radiation Lethality
    • TABLE 33-1 Principal Deterministic Effects of Radiation Exposure on Humans and the Approximate Threshold Dose
    • TABLE 33-2 Summary of Acute Radiation Lethality
    • Prodromal Period
    • Latent Period
    • Manifest Illness
    • Hematologic Syndrome
    • Gastrointestinal Syndrome
    • Central Nervous System Syndrome
    • LD50/60
    • FIGURE 33-1 Radiation-induced death in humans follows a nonlinear, threshold dose-response relationship.
    • TABLE 33-3 Approximate LD50/60 for Various Species After Whole-Body Radiation Exposure
    • FIGURE 33-2 Mean survival time after radiation exposure shows three distinct regions. If death is attributable to hematologic or central nervous system (CNS) effects, the mean survival time will vary with dose. If gastrointestinal (GI) effects cause death, it occurs in approximately 4 days.
    • Mean Survival Time
    • Local Tissue Damage
    • FIGURE 33-3 A sectional view of the anatomic structures of the skin. The basal cell layer is most radiosensitive.
    • Effects on the Skin
    • FIGURE 33-4 These isoeffect curves show the relationship between the number of daily fractions and the total radiation dose that will produce erythema or moist desquamation. As the fractionation of the dose increases, so does the total dose required.
    • TABLE 33-4 Potential Radiation Responses of Skin from High-Dose Fluoroscopy
    • Effects on the Gonads
    • Ovaries
    • FIGURE 33-5 Progression of germ cells from the stem cell phase to the mature cell. The asterisk indicates the most radiosensitive cell.
    • Testes
    • Table 33-5 Response of Ovaries and Testes to Radiation
    • Hematologic Effects
    • Hemopoietic System
    • FIGURE 33-6 Four principal types of blood cells—lymphocytes, granulocytes, erythrocytes, and thrombocytes—develop and mature from a single pluripotential stem cell.
    • Hemopoietic Cell Survival
    • Cytogenetic Effects
    • FIGURE 33-7 Graphs showing the radiation response of the major circulating blood cells. A, 25 rad. B, 200 rad. C, 600 rad.
    • FIGURE 33-8 Chromosome damage in an irradiated human cancer cell.
    • FIGURE 33-9 A photomicrograph of the human cell nucleus at metaphase shows each chromosome distinctly. The karyotype is made by cutting and pasting each chromosome similar to paper dolls and aligning them largest to smallest. The left karyotype is male, and the right is female.
    • Normal Karyotype
    • Single-Hit Chromosome Aberrations
    • FIGURE 33-10 Single-hit chromosome aberrations after irradiation in G1 and G2. The aberrations are visualized and recorded during the M phase.
    • Multi-Hit Chromosome Aberrations
    • FIGURE 33-11 Multi-hit chromosome aberrations after irradiation in G1 result in ring and dicentric chromosomes in addition to chromatid fragments. Similar aberrations can be produced by irradiation during G2, but they are rarer.
    • FIGURE 33-12 Radiation-induced reciprocal translocations are multi-hit chromosome aberrations that require karyotypic analysis for detection.
    • Reciprocal Translocations
    • Kinetics of Chromosome Aberration
    • FIGURE 33-13 Dose-response relationships for single-hit aberrations are linear, nonthreshold, but those for multi-hit aberrations are nonlinear, nonthreshold.
    • Radiation Dose-Response Relationships for Cytogenetic Damage
    • The Human Genome
    • Summary
    • Challenge Questions
    • Chapter 34 Stochastic Effects of Radiation
    • Objectives
    • TABLE 34-1 Minimum Population Sample Required to Show That the Given Radiation Dose Significantly Elevated the Incidence of Leukemia
    • Local Tissue Effects
    • Skin
    • Chromosomes
    • Cataracts
    • FIGURE 34-1 Cyclotron used to produce radionuclides for nuclear medicine.
    • Life-Span Shortening
    • FIGURE 34-2 In chronically irradiated animals, the relationship between extent of life shortening and dose appears linear, nonthreshold. This graph shows the representative results of several such experiments with mice.
    • TABLE 34-2 Risk of Life-Span Shortening as a Consequence of Occupation, Disease, or Various Other Conditions
    • Risk Estimates
    • FIGURE 34-3 Radiation-induced life-span shortening is shown for American radiologists. The age at death among radiologists was lower than that of the general population, but this difference has disappeared.
    • TABLE 34-3 Death Statistics for Three Groups of Physicians
    • Relative Risk
    • Relative Risk
    • Excess Risk
    • Excess Risk
    • Absolute Risk
    • FIGURE 34-4 Slope of the linear, nonthreshold dose-response relationship is equal to the absolute risk. A and B show absolute risks of 3.4 and 6.2 cases per 106 persons/rad/year, respectively.
    • Radiation-Induced Malignancy
    • Leukemia
    • Atomic Bomb Survivors
    • TABLE 34-4 Summary of the Incidence of Leukemia in Atomic Bomb Survivors
    • FIGURE 34-5 Data from the atomic bomb survivors of Hiroshima (H) and Nagasaki (N) suggest a linear, nonthreshold dose-response relationship.
    • FIGURE 34-6 The incidence of leukemia among atomic bomb survivors increased rapidly for the first few years, then declined to natural incidence by approximately 1975.
    • Radiologists
    • Patients with Ankylosing Spondylitis
    • FIGURE 34-7 Results of observations of leukemia in patients with ankylosing spondylitis treated with x-ray therapy suggest a linear, nonthreshold dose-response relationship.
    • Leukemia in Other Populations
    • Cancer
    • FIGURE 34-8 Radiation-induced preneoplastic thyroid nodularity in three groups of persons whose thyroid glands were irradiated in childhood follows a linear, nonthreshold dose-response relationship.
    • Thyroid Cancer
    • Bone Cancer
    • Skin Cancer
    • Breast Cancer
    • Lung Cancer
    • Liver Cancer
    • Total Risk of Malignancy
    • Nuclear Reactor Incidents
    • Predicted Radiation-Induced Deaths at Three Mile Island
    • BEIR Committee
    • TABLE 34-5 BEIR Committee Estimated Excess Mortality From Malignant Disease in 100,000 People
    • Radiation and Pregnancy
    • FIGURE 34-9 Exposure at an early age can result in an excess bulge of cancer after a latent period.
    • FIGURE 34-10 The absolute risk model predicts that the excess radiation-induced cancer risk is constant for life.
    • FIGURE 34-11 The relative risk model predicts that the excess radiation-induced cancer risk is proportional to the natural incidence.
    • TABLE 34-6 Average Annual Risk of Death from Various Causes
    • Effects on Fertility
    • Irradiation In Utero
    • FIGURE 34-12 LD50/60 of mice in relation to age at time of irradiation.
    • FIGURE 34-13 After 2 Gya are delivered at various times in utero, a number of effects can be observed.
    • TABLE 34-7 Relative Risk of Childhood Leukemia After Irradiation In Utero by Trimester
    • TABLE 34-8 Summary of Effects After 100 mGyt In Utero
    • FIGURE 34-14 Irradiation of flies by H.J. Muller showed the genetic effects to be linear, nonthreshold. Note that the doses were exceedingly high.
    • Genetic Effects
    • Box 34-1 Additional Conclusions Regarding Radiation Genetics
    • Summary
    • Challenge Questions

Part VIII Radiation Protection

    • Chapter 35 Health Physics
    • Objectives
    • Radiation and Health
    • Cardinal Principles of Radiation Protection
    • Minimize Time
    • Box 35-1 Cardinal Principles of Radiation Protection
    • Time
    • Figure 35-1 Life expectancy as a function of year of birth.
    • Figure 35-2 Typical isoexposure contours during fluoroscopic examination (mGya/hr).
    • Maximize Distance
    • Distance
    • Use Shielding
    • Shielding
    • TABLE 35-1 Approximate Half-Value and Tenth-Value Layers of Lead and Concrete at Various Tube Potentials
    • Effective Dose
    • FIGURE 35-3 Application of the cardinal principles of radiation protection in radiology.
    • TABLE 35-2 Weighting Factors for Various Tissues
    • FIGURE 35-4 The relationship between tissue dose and effective dose during computed tomography.
    • FIGURE 35-5 Effective dose during posteroanterior chest radiography.
    • FIGURE 35-6 Effective dose for occupational radiation exposure is based on the occupational radiation monitor.
    • Patient Effective Dose
    • Radiologic Technologist Effective Dose
    • Box 35-2 Effective Dose During Computed Tomography
    • Box 35-3 Effective Dose during PA Chest Radiography
    • Box 35-4 Occupational/Radiation Effective Dose
    • Radiologic Terrorism
    • Radiologic Device
    • Figure 35-7 Radiation detection instrument designed especially for radiologic terrorism.
    • Radiation Protection Guidance
    • Radiation Detection and Measurement Equipment
    • Summary
    • Challenge Questions
    • Chapter 36 Designing for Radiation Protection
    • Objectives
    • Radiographic Protection Features
    • Protective X-ray Tube Housing
    • Control Panel
    • Source-to-Image Receptor Distance Indicator
    • Collimation
    • Positive-Beam Limitation
    • Beam Alignment
    • FIGURE 36-1 Measurement of x-ray beam intensity as a function of added filtration results in a half-value layer (HVL) of 2.0 mm Al.
    • Filtration
    • Reproducibility
    • Linearity
    • Operator Shield
    • Mobile X-ray Imaging System
    • Fluoroscopic Protection Features
    • Source-to-Skin Distance
    • FIGURE 36-2 Patient entrance skin exposure (ESE) is considerably higher when the fluoroscopic x-ray tube is too close to the tabletop.
    • Primary Protective Barrier
    • Box 36-1 Effect of SSD on ESE
    • Filtration
    • Collimation
    • Exposure Control
    • Bucky Slot Cover
    • Protective Curtain
    • Cumulative Timer
    • Dose Area Product
    • FIGURE 36-3 A, Isoexposure profile for an unshielded fluoroscope demonstrates the need for protective curtains and Bucky slot covers. B, Isoexposure profile with these protective devices.
    • Design of Protective Barriers
    • Type of Radiation
    • FIGURE 36-4 Three types of radiation—the useful beam, leakage radiation, and scatter radiation—must be considered when the protective barriers of an x-ray room are designed.
    • TABLE 36-1 Lead and Concrete Equivalents for Primary Protective Barrier
    • TABLE 36-2 Equivalent Material Thicknesses for Secondary Barriers
    • Factors That Affect Barrier Thickness
    • Distance
    • TABLE 36-3 Levels of Occupancy of Areas That May Be Adjacent to X-ray Rooms, as Suggested by the NCRP
    • Occupancy
    • Control
    • Workload
    • Use Factor
    • kVp
    • FIGURE 36-5 Workload distribution of clinical voltage.
    • Radiation Detection and Measurement
    • TABLE 36-4 Radiation Detection and Measuring Device Characteristics and Uses
    • Gas-Filled Detectors
    • FIGURE 36-6 The ideal gas-filled detector consists of a cylinder of gas and a central collecting electrode. When a voltage is maintained between the central electrode and the wall of the chamber, electrons produced in ionization can be collected and measured.
    • Region of Recombination
    • Ion Chamber Region
    • FIGURE 36-7 The amplitude of the signal from a gas-filled detector increases in stages as the voltage across the chamber is increased.
    • FIGURE 36-8 This portable ion chamber survey instrument is useful for radiation surveys when exposure levels are in excess of 10 µGya/hr.
    • FIGURE 36-9 This ion chamber dosimeter is used for accurate measurement of diagnostic x-ray beams.
    • FIGURE 36-10 This configuration of an ion chamber is called a dose calibrator. It is used in nuclear medicine to measure accurately quantities of radioactive material.
    • Proportional Region
    • Geiger-Muller Region
    • Region of Continuous Discharge
    • Scintillation Detectors
    • The Scintillation Process
    • FIGURE 36-11 During scintillation, the intensity of light emitted is proportional to the amount of energy absorbed in the crystal.
    • Types of Scintillation Phosphors
    • The Scintillation Detector Assembly
    • Photomultiplier Tube Gain
    • FIGURE 36-12 Scintillation detector assembly characteristics of the type used in a portable survey instrument.
    • Thermoluminescence Dosimetry
    • FIGURE 36-13 Thermoluminescence dosimetry is a multistep process. A, Exposure to ionizing radiation. B, Subsequent heating. C, Measurement of the intensity of emitted light.
    • FIGURE 36-14 Thermoluminescence glow curve for lithium fluoride (LiF).
    • The Glow Curve
    • Types of Thermoluminescence Dosimetry Material
    • TABLE 36-5 Some Thermoluminescent Phosphors and Their Characteristics and Uses
    • Properties of Thermoluminescence Dosimetry
    • Optically Stimulated Luminescence Dosimetry
    • FIGURE 36-15 Optically stimulated luminescence dosimetry is a multistep process. A, Exposure to ionizing radiation. B, Laser illumination. C, Measurement of the intensity of stimulated light emission.
    • Summary
    • Challenge Questions
    • Chapter 37 Patient Radiation Dose Management
    • Objectives
    • Patient Dose Descriptions
    • TABLE 37-1 Representative Radiation Quantities From Various Diagnostic X-ray Procedures
    • Estimation of Patient Dose
    • Entrance Skin Dose
    • FIGURE 37-1 This family of curves is a nomogram for estimating output x-ray intensity from a single-phase radiographic unit.
    • FIGURE 37-2 This type of nomogram is very accurate but must be fashioned individually for each radiographic unit.
    • Mean Marrow Dose
    • Genetically Significant Dose
    • TABLE 37-2 Distribution of Active Bone Marrow in Adults
    • Genetically Significant Dose
    • TABLE 37-3 Genetically Significant Dose Estimated From Diagnostic X-ray Examination
    • Patient Dose in Special Examinations
    • Dose in Mammography
    • FIGURE 37-3 Two mammographic exposures result in a total glandular dose that is the sum of the individual glandular doses.
    • Dose in Computed Tomography Imaging
    • FIGURE 37-4 Patient dose distribution in step-and-shoot multislice spiral computed tomography is complicated because the profile of the x-ray beam cannot be made sharp.
    • FIGURE 37-5 Patient radiation dose is lower with higher multislice computed tomography because the beam penumbra is less for a given imaged anatomy.
    • FIGURE 37-6 When two detector rows are combined for the same beam width, patient dose will be lower.
    • Computed Tomography Patient Dose
    • Reduction of Unnecessary Patient Radiation Dose
    • Unnecessary Examinations
    • Mass Screening for Tuberculosis
    • Hospital Admission
    • Preemployment Physicals
    • Periodic Health Examinations
    • Emergency Room CT
    • Whole-Body Multislice Helical CT Screening
    • Repeat Examinations
    • Radiographic Technique
    • Image Receptor
    • Patient Positioning
    • Specific Area Shielding
    • The Pregnant Patient
    • Radiobiologic Considerations
    • FIGURE 37-7 Examples of useful contact gonad shields, which can be a piece of vinyl lead (A) or shaped (B).
    • FIGURE 37-8 A, Shadow shield. B, Shadow shield suspended above the beam-defining system casts a shadow over the gonads.
    • Box 37-1 Gonad Shielding
    • Time Dependence
    • Dose Dependence
    • Patient Information
    • Elective Booking
    • Patient Questionnaire
    • FIGURE 37-9 X-ray consent for women of childbearing age.
    • Posting
    • FIGURE 37-10 Wall posters with warnings about radiation and pregnancy are available from the National Center for Devices and Radiological Health.
    • TABLE 37-4 Representative Entrance Exposures and Fetal Doses for Radiographic Examinations Frequently Performed With a 400-Speed Image Receptor
    • Patient Dose Trends
    • FIGURE 37-11 Current estimated levels of human radiation exposure.
    • Summary
    • Challenge Questions
    • Chapter 38 Occupational Radiation Dose Management
    • Objectives
    • Occupational Radiation Exposure
    • Fluoroscopy
    • TABLE 38-1 Occupational Radiation Exposure of Radiologic Personnel
    • Interventional Radiology
    • FIGURE 38-1 Scatter radiation during portable fluoroscopy is more intense with the x-ray tube over the patient.
    • Mammography
    • Computed Tomography
    • Surgery
    • FIGURE 38-2 Isoexposure profiles (in mR/360 degrees) in horizontal and vertical planes for multislice spiral computed tomography.
    • Mobile Radiology
    • Radiation Dose Limits
    • Whole-Body Dose Limits
    • TABLE 38-2 Fatal Accident Rates in Various Industries
    • TABLE 38-3 Historical Review of Dose Limits for Occupational Exposure
    • FIGURE 38-3 Dose limits over the years.
    • TABLE 38-4 Dose Limits Recommended by the National Council on Radiation Protection and Measurements
    • Effective Dose
    • TABLE 38-5 Weighting Factors for Various Types of Radiation
    • Dose Limits for Tissues and Organs
    • Skin
    • Extremities
    • Lens
    • TABLE 38-6 Weighting Factors for Various Tissues
    • Public Exposure
    • Educational Considerations
    • Reduction of Occupational Radiation Exposure
    • Occupational Radiation Monitoring
    • Film Badges
    • FIGURE 38-4 Some representative radiation monitors. In many, metal filters are incorporated to help identify the type of radiation and its energy.
    • Thermoluminescence Dosimeters
    • FIGURE 38-5 Thermoluminescence dosimeters are available as chips, discs, rods, and powder. These are used for area and environmental radiation monitoring, and especially for occupational radiation monitoring.
    • Optically Stimulated Luminescence
    • FIGURE 38-6 Optically stimulated luminescence dosimeters.
    • Where to Wear the Occupational Radiation Monitor
    • Occupational Radiation Monitoring Report
    • FIGURE 38-7 Occupational radiation monitoring report must include the items of information shown here.
    • Protective Apparel
    • TABLE 38-7 Some Physical Characteristics of Protective Lead Aprons
    • Position
    • Patient Holding
    • Pregnant Technologist/Radiologist
    • FIGURE 38-8 When the fluoroscopist is pregnant, a second “baby monitor” should be positioned under the protective apron.
    • Management Principles
    • New Employee Training
    • In-Service Training
    • TABLE 38-8 Pregnancy in Diagnostic Radiology
    • Emphasize
    • Counseling During Pregnancy
    • FIGURE 38-9 Form for new employee notification.
    • Summary
    • FIGURE 38-10 Form for acknowledgement of radiation risk during pregnancy.
    • Challenge Questions

Glossary

    • Glossary

Index

    • Index
    • A
    • B
    • C
    • D
    • E
    • F
    • G
    • H
    • I
    • J
    • K
    • L
    • M
    • N
    • O
    • P
    • Q
    • R
    • S
    • T
    • U
    • V
    • W
    • X
    • Y
    • Z

Review of Basic Physics

    • Review of Basic Physics
    • Electrostatics
    • Electrodynamics
    • Magnetism
    • Electromagnetism
    • Classical Physics
    • Useful Units in Radiology
    • SI Prefixes
    • SI Base Units
    • SI Derived Units Expressed in Terms of Base Units
    • Special Quantities of Radiologic Science and Their Associated Special Units

Conversion Tables

  • Conversion Tables
  • Length
  • Mass-energy*
  • Time
  • SI Derived Units With Special Names
  • Summary of New and (Old) Radiologic Units
  • Universal Constants

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