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first year exit > Physics > Flashcards

Physics Flashcards

1
Q

Matter

A

Anything that occupies space and has mass.

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2
Q

Atoms

A

All matter is composed of fundamental building blocks

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3
Q

Mass

A

is the quantity of matter as described by its energy equivalence.

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4
Q

Weight

A

Mass and weight may be considered to be the same but that in the strictest sense, they are not the same. Mass is actually described by its energy equivalence, weight is the force exerted on a body under the influence of gravity.

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5
Q

Mass

A

measured in kilograms

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6
Q

Kilo

A

stands for 1000

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7
Q

Building blocks of matter

A

atoms and molecules

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8
Q

Energy

A

is the ability to do work

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9
Q

Potential Energy

A

the ability to do work by virtue of position.

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10
Q

Kinetic energy

A

is the energy of motion

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11
Q

Chemical energy

A

energy released by a chemical reaction

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12
Q

Electrical energy

A

represents the work that can be done when an electron moves through an electron potential difference (voltage).

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13
Q

Thermal energy

A

energy of motion at the molecular level

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14
Q

Nuclear energy

A

energy that is contained within the nucleus of an atom.

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15
Q

Electromagnetic energy

A

x-rays, radio waves, microwaves; and ultraviolet, infrared, and visible light.

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16
Q

Mass-Energy (Einstein)

E=mc^2

A

Where E is energy, m is mass, and c is the velocity (speed) of electromagnetic radiation (light) in a vacuum

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17
Q

Radiation

A

energy emitted and transferred through space

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18
Q

Electromagnetic radiation

A

visible light, a form of electromagnetic energy, is radiated by the sun.

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19
Q

Electromagnetic energy

A

usually referred to as electromagnetic radiation or, simply, radiation.

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20
Q

Exposed or Irradiated

A

Matter that intercepts radiation and absorbs part or all of it.

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21
Q

Ionizing radiation

A

is a special type of radiation that includes x-rays.

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22
Q

Ionization

A

is the removal of an electron from an atom

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23
Q

Ion pair

A

Two opppositely charged particles

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24
Q

1% voltage ripple

A

High frequency generators that higher x-ray quantity and quality

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25
Q

100% voltage ripple

A

Single phase power in which the voltage varies from zero to its maximum value

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26
Q

14% ripple

A

Three-phase, six pulse power whose voltage supplied to the x-ray tube never falls below 86% of peak value.

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27
Q

4% voltage ripple

A

Three phase, 12 pulse power whose voltage supplied to the x-ray tube never falls below 96% of peak value.

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28
Q

Abrasion layer

A

Protective covering of gelatin that encloses an emulsion.

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29
Q

Absorbed dose

A

Energy transferred from ionizing radiation per unit mass of irradiated material; expressed in rad (100 erg/g) or gray (1 J/kg).

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30
Q

Absorption blur

A

Characteristic of a subject that affects subject contrast

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31
Q

Absorption

A

Transfer of energy from an electromagnetic field to matter; removal of x-rays from a beam via the photoelectric effect.

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32
Q

Acceleration

A

Rate of change of velocity over time

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33
Q

Acceleration of gravity

A

constant rate at which objects falling to the Earth accelerate.

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34
Q

Acetic acid

A

chemical used in the stop bath

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35
Q

Activator

A

chemical, usually acetic acid in the fixer and sodium carbonate in the developer, used to neutralize the developer and swell the gelatin.

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36
Q

Active memory

A

data can be stored or accessed at random from anywhere in main memory in approximately equal amounts of time, regardless of where the data are located.

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37
Q

Actual focal spot size

A

Area on the anode target that is exposed to electrons from the tube current.

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38
Q

Acute radiation syndrom

A

Radiation sickness that occurs in humans after whole body doses of 1 Gy (100 rad) or more of ionizing radiation delivered over a short time.

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39
Q

Adhesive layer

A

Protective covering of gelatin that encloses the emulsion

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40
Q

Aerial oxidation

A

Oxidation that occurs when air is introduced into the developer after it is mixed, handled, and stored.

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41
Q

Afterflow

A

phosphorescence in an intensifying screen.

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42
Q

Air gap technique

A

Practice of moving the image receptor 10 to 15 cm from the patient so that fewer scattered x-rays interact with the image receptor, thereby enhancing contrast.

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43
Q

ALARA

A

As low as reasonably achievable

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44
Q

Algorithm

A

Computer adapted mathematical calculation applied to raw data during image reconstruction

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45
Q

Alpha particle

A

Particulate form of ionizing radiation that consists of two protons and two neutrons; nucleus of helium emitted from the nucleus of a radioactive atom.

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46
Q

Alternating current (AC)

A

Oscillation of electricity in both directions within a conductor.

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47
Q

Amber filter

A

Filter that transmits light with wavelengths longer than 550 nm, which is above the spectral response of blue sensitive film

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48
Q

Ammeter

A

Device that measures current

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49
Q

Ampere (A)

A

SI unit of electric charge: 1 A = 1 C/s

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50
Q

Amplitude

A

Width of a waveform

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51
Q

Anabolism

A

Process of synthesizing smaller molecules into a larger macromolecule.

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52
Q

Anaphase

A

Third phase of mitosis, during which chromatids repel one another and migrate along the mitotic spindle to opposite sides of the cell.

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53
Q

Anatomically programmed radiography (APR)

A

Technique by which graphics on the console guide the technologist in selection of a desired kVp and mAs.

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54
Q

Anode

A

Positively charged side of an x-ray tube that contains the target.

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55
Q

Anthropomorphic

A

Human characteristics

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56
Q

Aperture diaphragm

A

Simple beam restricting device that attaches a lead-lined metal diaphragm to the head of the x-ray tube.

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57
Q

Aperture

A

circular opening for the patient in the gantry of a computed tomographic or magnetic resonance imaging system. B) fixed collimation of a diagnostic x-ray tube, as in an aperture diaphragm.

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58
Q

Archival quality

A

Attribute that refers to the fact that the image does not deteriorate with age but remains in its original state.

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59
Q

Area beam

A

X-ray beam pattern that usually is shaped like a square or a rectangle, and that is used in conventional radiography and fluoroscopy.

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60
Q

Array processor

A

Part of a computer that handles raw data and performs the mathematical calculations necessary to reconstruct a digital image.

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61
Q

Artifact

A

Unintended optical density on a radiograph or another film type image receptor.

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62
Q

Asthenic

A

Referring to the body habitus of a patient who is small and frail.

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63
Q

Atom

A

Smallest particle of an element that cannot be divided or broken by chemical means.

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64
Q

Atomic mass number

A

Number of protons plus number of neutrons in the nucleus.

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65
Q

Atomic mass unit

A

Mass of a neutral atom of an element, expressed as one twelfth the mass of carbon, which has an assigned value of 12.

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66
Q

Atomic mass

A

Relative mass of a specific isotope of an element.

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67
Q

Atomic number (Z)

A

Number of protons in the nucleus.

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68
Q

Atrophy

A

Shrinking of a tissue or organ.

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69
Q

Attenuation

A

Reduction in radiation intensity that results from absorption and scattering.

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70
Q

Automatic brightness control (ABC)

A

Feature on a fluoroscope that allows the radiologist to select an image brightness level that is subsequently maintained automatically by varying the kVp, the mAs, or both.

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71
Q

Automatic exposure control (AEC)

A

Feature that determines radiation exposure during radiography in most x-ray imaging systems.

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72
Q

Autotransformer law

A

Principle stating that the voltage received and the voltage provided are directly related to the number of turns of the transformer enclosed by the respective connections.

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73
Q

Autotransformer

A

Transformer located in the operating console that controls the kVp; it consists of one winding of wire and varies voltage and current by self induction.

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74
Q

Average gradient

A

Measure of radiographic contrast

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75
Q

Axial tomography

A

Conventional tomography in which the plane of the image is parallel to the long axis of the body; this results in sagittal and coronal images.

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76
Q

Axial

A

perpendicular to the long axis of the body

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77
Q

Backscatter radiation

A

X-rays that have interacted with an object and are deflected backward.

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78
Q

Bandpass

A

Number of times per second that the electron beam can be modulated.

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79
Q

Base density

A

Optical density inherent in the base of the film.

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80
Q

Base plus fog

A

Average density from an unexposed area of the strips.

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81
Q

Base

A

Area that serves as a mechanical support for the active phosphor layer in a radiographic intensifying screen.

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82
Q

Beam axis

A

Central line that represents maximal ultrasound or xray intensity

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83
Q

Beam penetrability

A

Ability of an xray beam to penetrate tissue.

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84
Q

Beam restrictor

A

Device that restricts the size of the xray field to only the anatomical structure of interest.

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85
Q

Beam limiting device

A

Device that provides a means of restricting the size of an x-ray field.

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86
Q

Becquerrel (Bq)

A

Special name for the SI units of radioactivity. One becquerel is equal to disintegration per second.

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87
Q

Beta particle

A

Ionizing radiation with characteristics of an electron; emitted from the nucleus of a radioactive atom.

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88
Q

Binary number system

A

Number system with only two digits, 0 and 1.

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89
Q

Bipolar

A

Magnet that has two poles

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90
Q

Bit depth

A

Number of bits used to reproduce image gray levels (eg., 8 bits=2^8=256 gray levels)

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91
Q

Bit

A

smallest unit of measure in computer storage capacity

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92
Q

Body habitus

A

General size and shape of a patient

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93
Q

Brachytherapy

A

Radiation oncology in which the source of tradition is on or in the body.

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94
Q

Bremsstrahlung x-ray

A

X-rays that results from interaction of the projectile electron with a target nucleus; braking radiation.

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95
Q

Brightness gain

A

Ability of the image intensifier to increase the illumination level of the image.

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96
Q

Bucky factor

A

Ratio of incident radiation to transmitted radiation through a grid; ratio of patient dose with and without a grid.

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97
Q

Bucky slot cover

A

Protective cover that automatically shields the Bucky slot opening during fluoroscopic examinations when the Bucky tray is at the foot of the table.

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98
Q

Buffer

A

Acetate added to the fixer to maintain a constant pH

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99
Q

Buffering agent

A

Alkali compound in the developer that enhances the action of the developing agent by controlling the concentration of hydrogen ions.

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100
Q

Byte

A

Group of eight bits; represents one character or digit.

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101
Q

Calipers

A

Instrument with two bent or curved legs used for measuring the thickness of a solid.

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102
Q

Calorie

A

Energy necessary to raise the temperature of 1 g of water by 1 celcius

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103
Q

C-arm fluoroscope

A

Portable device for fluoroscopy. The opposite ends of the C-shaped support arm hold the image intensifier and the xray tube.

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104
Q

Cassette

A

Rigid holder the contains the film and screens.

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105
Q

Cassette loaded spot film

A

conventional method of capturing images with image intensified fluoroscopes.

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106
Q

Catabolism

A

process that creates energy for a cell by breaking down molecular nutrients that are brought to and diffused through the cell membrane.

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107
Q

Cathode ray tube

A

Electron beam tube designed for a two dimensional display of signals

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108
Q

Cathode rays

A

Stream of electrons

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109
Q

Cathode

A

negative side of the x-ray tube; contains the filament and the focusing cup

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110
Q

Cell cloning

A

Process by which normal cells produce a visible colony in a short time.

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111
Q

Cell cycle time

A

Average time from one mitosis to another

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112
Q

Cell theory

A

Principle that all plants and animals contain cells as their basic functional units.

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113
Q

Cell

A

Basic unit of all living matter.

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114
Q

Central Axis x ray beam

A

X-ray beam composed of x-rays that travel along the center of the useful x-ray beam.

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115
Q

Central processing unit

A

Processing hardware in large computers

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116
Q

Central ray

A

Center of the xray beam that interacts with the image receptor

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117
Q

Centrifugal force

A

force that keeps an electron in orbit

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118
Q

Characteristic Curve

A

Graph of optical density versus log relative response; H&D curve.

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119
Q

Characteristic x-ray

A

X-ray released as a result of the photoelectric effect; its discrete energies are determined by the respective electron biding energy.

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120
Q

Charge coupled device

A

Solid state device that converts visible light photons to electrons.

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121
Q

Chemical Energy

A

Energy released by a chemical reaction

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122
Q

chemical fog

A

Artifact produced by chemical contamination of the developer

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123
Q

Chemical symbol

A

Alphabetic abbreviation for an element.

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124
Q

Chip

A

Tiny piece of semiconductor material

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125
Q

Classical scattering

A

Scattering of x-rays with no loss of energy. Also called coherent, Rayleigh, or thompson scattering.

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126
Q

Clearing agent

A

A chemical, usually ammonium thiosulfate, that is added to the fixer to remove undeveloped silver bromine from the emulsion.

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127
Q

Collimation

A

Restriction of the useful x-ray beam to reduce patient size and shape.

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128
Q

Commutator

A

Device that acts like a switch, converting an alternating current generator to a direct current generator.

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129
Q

Compensating filter

A

Material inserted between an x-ray source and a patient to shape the intensity of the x-ray beam. An x-ray beam filter is designed to make the remnant beam more uniform in intensity.

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130
Q

Compression device

A

Device that maintains close screen film contact when the cassette is closed and latched.

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131
Q

Compression

A

The act of flattening soft tissue to improve optical density.

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132
Q

Compton effect

A

Scattering of x-rays that results in ionization and loss of energy.

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133
Q

Compton scattering

A

Interaction between an x-ray and a loosely bound outer-shell electron that results in ionization and x-ray scattering.

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134
Q

Computed Radiography

A

Radiographic technique that uses a photostimulable phosphor as the image receptor and an area beam.

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135
Q

Computed tomography

A

Creation of a cross sectional tomographic section of the body with a rotating fan beam, a detector array, and computed reconstruction.

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136
Q

Computed tomography dose index

A

Radiation dose in a single slice over a 10 cm length so that dose delivered beyond the selected slice thickness is included.

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137
Q

Computer aided detection

A

Use of a highly complex pattern recognition

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138
Q

Conduction

A

Transfer of heat by molecular agitation

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139
Q

Conductor

A

Material that allows heat or electric current to flow

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140
Q

Cone cutting

A

Misalignment of cones that causes one side of the radiograph to not be exposed because the edge of the cone may interfere with the x-ray beam.

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141
Q

Cone

A

Circular metal tube that attaches to x-ray tube housing to limit the beam size and shape.

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142
Q

Cones and Cylinders

A

Modifications of the aperture diaphragm.

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143
Q

Connective tissue

A

Tissue that binds tissue and organs together

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144
Q

Contrast Agent

A

Compound used as an aid for imaging internal organs with x-rays.

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145
Q

Contrast improvement factor

A

Ratio of radiographic contrast with a grid to that without a grid.

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146
Q

Contrast Index

A

Difference between the step with an average optical density closest to 2.2 and the step with an average optical density closest to, but not less than, 0.5.

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147
Q

Contrast medium

A

Agent that enhances differences between anatomical structures.

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148
Q

Contrast resolution

A

Ability to distinguish between and to image similar tissues.

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149
Q

Contrast

A

Degree of difference between the light and dark areas of a radiograph.

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150
Q

Convection

A

Transfer of heat by the movement of hot matter to a colder place.

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151
Q

Conversion efficiency

A

Rate at which x-ray energy is transformed into light in an intensifying screen.

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152
Q

Conversion factor

A

Ratio of illumination intensity at the output phosphor to radiation intensity incident on the input phosphor.

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153
Q

Coolidge tube

A

Type of vacuum tube is use today that allows x-ray intensity and energy to be selected separately and accurately.

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154
Q

Cosmic rays

A

Particulate and electromagnetic radiation emitted by the sun and the stars.

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155
Q

Coulomb

A

SI unit of electric charge

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156
Q

Coupling

A

Joining of magnetic fields produced by the primary and secondary coils.

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157
Q

Covalent bond

A

Chemical union between atoms formed by sharing one or more pairs of electrons.

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158
Q

Covering power

A

The more efficient use of silver in an emulsion to produce the same optical density per unit exposure.

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159
Q

Crookes tube

A

Forerunner of modern fluorescent, neon, and x-ray tubes.

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160
Q

Crossed grid

A

Grid on which lead strips run parallel to the long and short axes.

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161
Q

Crossover rack

A

Device in an automatic processor that transports film from one tank to the next.

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162
Q

Cytoplasm

A

Protoplasm that exists outside the cell’s nucleus

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163
Q

Cytosineose

A

Nitrogenous organic base that attaches to a deoxyribose molecule.

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164
Q

Decimal system

A

System of numbers based on multiples of ten

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165
Q

Densitometer

A

Instrument that measures the optical density of exposed film.

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166
Q

Density difference

A

The difference between the step with an average optical density closest to 2.2 and the step with an average optical density closest to, but not less than, 0.5.

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167
Q

Detail

A

Degree of sharpness of structural lines on a radiograph.

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168
Q

Detective quantum efficiency

A

Percentage of x-rays absorbed by the image receptor.

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169
Q

Detector array

A

Group of detectors and the interspace material used to separate them; the image receptor in computed tomography.

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170
Q

Developing agent

A

A chemical, usually phenidone, hydroquinone, or Metol that reduces exposed silver ions to atomic silver.

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171
Q

Developing

A

Stage of processing during which the latent image is converted to a manifest image.

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172
Q

Development fogat enables imaging systems from different manu

A

Artifact that results from reduction of crystals that had not been exposed to metallic silver caused by the lack of a restrainer.

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173
Q

Diaphragm

A

Device that restricts an x-ray beam to a fixed size.

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174
Q

DICOM

A

Digital Imging and Communications in Medicine—Standard that enables imaging systems from different manufacturers to communicate.

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175
Q

Differential absorption

A

Different degrees of absorption in different tissues that result in image contrast and formation of the xray image.

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176
Q

Dimensional stability

A

Property that allows the base of radiographic film to maintain its size and shape during use and processing, so it does not contribute to image distortion.

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177
Q

Diode

A

Vacuum tube with two electrodes–a cathode and an anode.

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178
Q

Dipolar

A

Referring to a molecule with areas of opposing electric charge.

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179
Q

Direct current

A

flow of electricity in only one direction within a conductor.

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180
Q

Direct effect

A

Effect of radiation that occurs when ionizing radiation interacts directly with a particularly radiosensitive molecule.

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181
Q

Direct current motor

A

Electric motor in which many turns of wire are used for the current loop and many bar magnets are used to create the external magnetic field.

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182
Q

Direct exposure film

A

film used without intensifying screens.

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183
Q

Distortion

A

Unequal magnification of different portions of the same object.

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184
Q

Dose equivalent

A

Radiation quantity that is used for radiation protection and that expresses dose on a common scale for all radiation. Expressed in rem or sievert.

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185
Q

Dose length product

A

Product of computed tomography dose index and slice thickness. Depends only on selected computed tomography parameters and does not reflect patient dose.

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186
Q

Dose Limit

A

Maximum permissible occupational radiation dose.

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187
Q

Dose

A

Amount of radiant energy absorbed by an irradiated object.

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188
Q

Dosimeter

A

Instrument that detects and measures exposure to ionizing radiation.

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189
Q

Dosimetry

A

The practice of measuring the intensity of radiation.

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190
Q

Double contrast examination

A

Examination of the colon that uses air and barium for contrast.

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191
Q

Double emulsion film

A

Radiographic film that has an emulsion coating on both sides of the base and a layer of supercoat over each emulsion.

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192
Q

Double helix

A

configuration of DNA that is shaped like a ladder twisted about an imaginary axis like a spring.

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193
Q

Dynamic range

A

Range of values that can be displayed by an imaging system; shades of gray.

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194
Q

Eddy current

A

Current that opposes the magnetic field that induced it, creating a loss of transformer efficiency

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195
Q

Edge enhancement

A

Accentuation of the interface between different tissues.

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196
Q

Edge response function

A

Mathematical expression of the ability of the computed tomographic scanner to reproduce a high contrast edge with accuracy.

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197
Q

Effective atomic number

A

Weighted average atomic number for the different elements of a material.

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198
Q

Effective dose

A

Sum of specified tissues of the products of equivalent dose in a tissue and the weighting factor for the tissue. Effective dose is a method of converting a nonuniform radiation dose, as when a protective apron is worn, to a dose, with respect to risk, as if the whole body were exposed.

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199
Q

Effective dose equivalent

A

Sum of the products of the dose equivalent to a tissue and the weighting factors applicable to each of the tissues irradiated. The values are different for effective dose and effective dose equivalent.

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200
Q

Effective focal spot size

A

Area projected onto the patient and the image receptor.

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201
Q

Electric current

A

Flow of electrons

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202
Q

Electric field

A

Lines of force exerted on charged ions in the tissues by the electrodes that cause charged particles to move from one pole to another.

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203
Q

Electrical energy

A

Work that can be done when an electron or an electronic charge moves through an electric potential.

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204
Q

Electricity

A

form of energy created by the activity of electrons and other subatomic particles in motion.

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205
Q

Electrification

A

Process of adding or removing electrons from a substance.

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206
Q

Electrifiation

A

Process of adding or removing electrons from a substance.

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207
Q

Electrified object

A

Object that has too few or too many electrons.

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208
Q

Electrode

A

Electrical terminal or connector.

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209
Q

Electromagnet

A

Coil or wire wrapped around an iron core that intensifies the magnetic field.

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210
Q

Electromagnetic energy

A

Type of energy in x-rays, radio waves, microwaves, and visible light.

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211
Q

Electromagnetic radiation

A

Oscillating electric and magnetic field that travel in a vacuum with the velocity of light. Includes x-rays, gamma rays, and some nonionizing radiation (such as ultraviolet, visible, infrared, and radio waves).

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212
Q

Electromagnetic spectrum

A

Continuum of electromagnetic energy.

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213
Q

Electromotive force

A

Electric potential; measured in volts.

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214
Q

Electron binding energy

A

Strength of attachment of an electron to the nucleus.

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215
Q

Electron optics

A

Engineering aspects of maintaining proper electron to the nucleus

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216
Q

Electron spin

A

Momentum of a particle of an atom in a fixed pattern.

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217
Q

Electron volt

A

Unit of energy equal to that which an electron acquires from a potential difference of 1 V.

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218
Q

Electron

A

Elementary particle with one negative charge. Electrons surround the positively charged nucleus and determine the chemical properties of the atom.

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219
Q

Electrostatics

A

Study of fixed or stationary electric charge.

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220
Q

Element

A

Atoms that have the same atomic number and the same chemical properties. Substance that cannot be reduced further without changing its chemical properties.

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221
Q

Elemental mass

A

Characteristic mass of an element, determined by the relative abundance of isotopes and their respective atomic masses.

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222
Q

Elongation

A

Image that is made to appear longer than it really is because the inclined object is not located on the central x-ray beam.

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223
Q

Emulsion

A

Material with which x-rays or light photons from screens interact and transfer information.

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224
Q

Endoplasmic reticulum

A

Channel or series of channels that allows the nucleus to communicate with the cytoplasm.

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225
Q

Energy levels

A

Orbits around the nucleus that contain a designated number of electrons.

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226
Q

Energy subtraction

A

technique that uses the two x-ray beams alternately to provide a subtraction image that results from differences in photoelectric interaction.

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227
Q

Energy

A

Ability to do work; measured in joules.

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228
Q

Entrance roller

A

Roller that grips the film to begin its trip through the processor.

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229
Q

Entrance skin exposure

A

X-ray exposure to the skin; expressed in milliroentgen

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230
Q

Enzyme

A

Molecule that is needed in small quantities to allow a biochemical reaction to continue, even though it does not directly enter into the reaction.

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231
Q

Epithelium

A

Covering tissue that lines all exposed surfaces of the body, both exterior and interior.

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232
Q

Erg (joule)

A

Unit of energy and work

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233
Q

Excitation

A

Addition of energy to a system achieved by raising the energy of electrons with the use of x-rays.

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234
Q

Exit radiation

A

x-rays that remain after the beam exits through the patient.

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235
Q

Exposed matter

A

Matter that intercepts radiation and absorbs part or all of it; irradiated matter.

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236
Q

Exposure factors

A

Factors that influence and determine the quantity and quality of x-radiation to which the patient is exposed.

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237
Q

Exposure linearity

A

Ability of a radiographic unit to produce a constant radiation output for various combinations of mA and exposure time.

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238
Q

Exposure

A

Measure of the ionization produced in air by x-rays or gamma rays. Quantity of radiation intensit expressed in roentgen (R), Coulombs per kologram (C/kg), or air kerma (Gy).

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239
Q

Extinction time

A

Time required to end an exposure

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240
Q

Extrafocal radiation, off focus radiation

A

Electrons that bounce off the focal spot and land on other areas of the target.

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241
Q

Extrapolation

A

Estimation of a value beyond the range of known vaues

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242
Q

Falling load generator

A

Design in which exposure factors are adjusted automatically t the highest mA at the shortest exposure time allowed by the high voltage generator.

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243
Q

Fan beam

A

X-ray beam pattern used in computed tomography and digital radiography; projected as a slit.

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244
Q

Feed tray

A

The start of the transport system, where the film to be processed is inserted into the automatic processor in the darkroom.

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245
Q

Ferromagnetic material

A

Material that is strongly attracted by a magnet and that usually can be permanently magnetized by exposure to a magnetic field.

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246
Q

Field of view

A

Image matrix size provided by digital x-ray imaging systems.

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247
Q

Field

A

Interactions among different energies, forces, or masses that cannot be seen but can be described mathematically.

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248
Q

Fifteen percent rule

A

Principle that states that if the optical density on a radiograph is to be increased with the use of a kVp, an increase in kvP by 15% is equivalent to doubing of the mAs.

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249
Q

Filament

A

Part of the cathode that emits electrons, resulting in a tube current.

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250
Q

File

A

Collection of data or information that is treated as a unit by the computer.

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251
Q

Film badge

A

Pack of photographic film used for approximate measurement of radiation exposure to radiation workers. It is the most widely used and most economical type of personnel radiation monitor.

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252
Q

Film graininess

A

Distribution of silver halide grains in an emulsion.

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253
Q

Filtered back projection

A

Process by which an image acquired during computed tomography and stored in computer memory is reconstructed.

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254
Q

Filtration

A

Removal of low energy x-rays from the useful beam with aluminum or another metal. It results in increased beam quality and reduced patient dose.

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255
Q

First generation computed tomographic scanner

A

Finely collimated x-ray beam, single detector assembly that translates across the patient and rotates between successive translations.

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256
Q

Five percent rule

A

Principle that states that an increase of 5% in the kVp may be accompanied by a 30% reduction in the mAs to produce the same optical density at a slightly reduced contrast scale.

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257
Q

Fixing

A

Stage of processing during which the silver halide not exposed to radiation is dissolved and removed from the emulsion.

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258
Q

Fluorescence

A

Emission of visible light only during stimulation

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259
Q

Fluorescent screen

A

Cycle in a television picture tube whereby the electron beam creates the television optical signal and then immediately fades.

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260
Q

Fluoroscope

A

Device used to image moving anatomical structures with x-rays

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261
Q

Fluoroscopy

A

Imaging modality that provides a continuous image of the motion of internal structures while the x-ray tube is energized. Real time imaging.

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262
Q

Flux gain

A

Ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor.

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263
Q

Focal spot

A

Region of the anode target in to produce x-rays.which electrons interact

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264
Q

Focal spot blur

A

Blurred region on the radiograph over which the technologist has little control.

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265
Q

Focused grid

A

Radiographic grid constructed so that the grid strips converge on an imaginary line.

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266
Q

Focusing cup

A

Metal shroud that surrounds the filament

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267
Q

Fog density

A

Development of silver grain that contains no useful information.

268
Q

Fog

A

Unintended optical density on a radiograph that reduces contrast through light or chemical contamination.

269
Q

Force

A

That which changes the motion of an object; a push or a pull. Expressed in newtons (N).

270
Q

Foreshortening

A

Reduction in image size; related to the angle of inclination of the object

271
Q

Fourth generator computed tomographic imaging system

A

Unit in which the x-ray source rotates but the detector assembly does not.

272
Q

Fraction

A

Numeric value expressed by dividing one number by another.

273
Q

Fractionated

A

Radiation dose delivered at the same dose in equal portions at regular intervals.

274
Q

Free radical

A

Uncharged molecule that contains a single unpaired electron in the valence shell.

275
Q

Frequency

A

Number of cycles or wavelengths of a simle harmonic motion per unit time. Expressed in Hertz (Hz). 1 Hz = 1 cycle/s.

276
Q

Fulcrum

A

Imaginary pivot point bout which the x-ray tube and the image receptor move.

277
Q

Full width at half maximum

A

Width of the profile at half its maximum value.

278
Q

Full wave rectification

A

circuit in which the negative half cycle corresponding to the inverse voltage is reversed, so a positive voltage is always directed across the x-ray tube.

279
Q

Fundamental laws of motion

A

The three principles of inertia, force, and action/reaction established by Isaac Newton.

280
Q

Fundamental particles

A

The three primary constituents of an atom: electrons, photons, and neutrons.

281
Q

Gantry

A

Portion of the computed tomographic or magnetic resonance imaging system that accommodates the patient and source or the detector assemblies.

282
Q

Gelatin

A

Part of the emulsion that provides mechanical support for the silver halide crystals by holding them uniformly dispersed in place.

283
Q

Gonadal dose

A

Exposure to the reproductive organs

284
Q

Gradient

A

Slope of the tangent at any point on the characteristic curve.

285
Q

Gray (Gy)

A

Special name for the SI unit of absorbed dose and air kerma. 1 Gy = 1 J/kg = 100 rad.

286
Q

Gray scale

A

Image display in which intensity is recorded as variations in brightness.

287
Q

Grid cleanup

A

Ability of a grid to absorb scatter radiation.

288
Q

Grid cutoff

A

Absence of optical density on a radiograph caused by unintended x-ray absorption in a grid.

289
Q

Grid frequency

A

Number of grid lines per inch or centimeter.

290
Q

Grid lines

A

Series of sections of radiopaque material.

291
Q

Grid ratio

A

Ratio of grid height to grid strip separation.

292
Q

Grid

A

Device used to reduce the intensity of scatter radiation in the remnant x-ray beam.

293
Q

Grid controlled tube

A

X-ray tube designed to be turned on and off very rapidly for situations that require multiple exposures at precise exposure times.

294
Q

Guanine

A

Nitrogenous organic base that attaches to a deoxyribose molecule.

295
Q

Halation

A

Reflection of screen light transmitted through the emulsion and base.

296
Q

Half-life

A

Time required for a quantity of radioactivity to be reduced to half its original value.

297
Q

Half-value layer (HVL)

A

Thickness of absorber necessary to reduce an x-ray beam to half its original intensity.

298
Q

Half wave rectification

A

Condition in which the voltage is not allowed to swing negatively during the negative half of its cycle.

299
Q

Hard copy

A

Permanent image on film or paper, as opposed to an image on a cathode ray tube, a disc, or magnetic tape.

300
Q

Hard x-ray

A

X-ray that has high penetrability and therefore is of high quality.

301
Q

Hardener

A

A chemical, usually potassium glutaraldehyde alum in the fixer, that is used to stiffen and shrink the emulsion.

302
Q

Hardware

A

Visible parts of the computer

303
Q

Heel effect

A

Absorption of x-rays in the heel of the target, resulting in reduced x-ray intensity to the anode side of the central axis.

304
Q

Hertz (Hz)

A

Unit of frequency; the number of cycles or oscillations that occur each second during simple harmonic motion.

305
Q

Hexadecimal number system

A

Number system used by low level applications to represent a set of four bits.

306
Q

High contrast resolution

A

Ability to image small objects with high subject contrast; spatial resolution

307
Q

High voltage generator

A

One of the three principal parts of an x-ray imaging system; it is always close to the x-ray tube.

308
Q

Homeostasis

A

a. State of equilibrium among tissue and organs. b. Ability of the body to return to normal function despite infection and environmental changes.

309
Q

Hormone

A

Protein manufactured by various endocrine glands and carried by the blood to regulate body functions such as growth and development.

310
Q

Horsepower

A

British unit of power

311
Q

Hounsfield unit

A

Scale of computed tomographic numbers used to assess the nature of tissue.

312
Q

Hypersthenic

A

Referring to a body habitus of a patient who is large in frame and overweight.

313
Q

Hythenicpo Retention

A

Undesirable retention of the fixer in emulsion.

314
Q

Hypo

A

Sodium thiosulfate, a fixing agent that removes unexposed and undeveloped silver halide crystals from the emulsion.

315
Q

Hyposthenic

A

Referring to a body habitus of a patient who is thin but healthy looking.

316
Q

Hysteresis

A

Additional resistance created by the alternate reversal of the magnetic field caused by the alternating current.

317
Q

Image detail

A

Sharpness of small structures on the radiograph

318
Q

Image intensifier

A

Electronic vacuum tube that amplifies a fluoroscopic image to reduce patient dose.

319
Q

Image matrix

A

Layout of cells in rows and columns.

320
Q

Image noise

A

Deterioration of the radiographic image

321
Q

Image receptor

A

Medium that transforms the x-ray beam into a visible image; radiographic film or a phosphorescent screen.

322
Q

Image receptor contrast

A

Contrast that is inherent in the film and is influenced by processing of the film.

323
Q

Image forming x-ray

A

X-ray that exits from the patient and enters the image receptor.

324
Q

Improper fraction

A

Fraction in which the quotient is greater than 1.

325
Q

Indirect effect

A

Effect of radiation that results from the production of free radicals produced by the interaction of radiation with water.

326
Q

Induction motor

A

Electric motor in which the rotor is a series of wire loops but the external magnetic field is supplied by several fixed electromagnets called stators.

327
Q

Induction

A

Process of making ferromagnetic material magnetic.

328
Q

Inertia

A

Property of matter that resists change in motion or at rest.

329
Q

Infrared light

A

Light that consists of photons with wavelengths longer than those of visible light but shorter than those of microwaves.

330
Q

Infrared radiation

A

Electromagnetic radiation just lower in the energy than visible light, with a wavelength in the range of 0.7 to 1000 um

331
Q

Inherent filtration

A

Filtration of useful x-ray beams provided by the permanently installed components of an x-ray tube housing assembly and the glass window of an x-ray tube.

332
Q

Initiation time

A

Time required to start an exposure

333
Q

input

A

Process of transferring information into primary memory

334
Q

Insulator

A

Material that inhibits the flow of electrons within a conductor or during heat transfer.

335
Q

Integrate mode

A

Function of an instrument designed to measure the total accumulated intensity of radiation over time.

336
Q

Intensification Factor

A

Ratio of exposure without screens to that with screens to produce the same optical density.

337
Q

Intensifying screen

A

Sensitive phosphor that converts x-rays to light to shorten exposure time and reduce patient dose.

338
Q

Intensity profile

A

Projection formed by the intensity of radiation detected according to the attenuation pattern.

339
Q

International System of Units (SI)

A

Standard system of units based on the meter, the kilogram, and the second; it has been adopted by all countries and is used in all branches of science.

340
Q

Interphase

A

Period of growth of the cell between divisions

341
Q

Interpolation

A

Estimation of a value between two known values

342
Q

Interrogation time

A

Time during which the signal from an image detector is sampled.

343
Q

Interspace material

A

Sections of radiolucent material in a grid.

344
Q

Inverse square law

A

Law that states that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation.

345
Q

Inverse voltage

A

Current that flows from the anode to the cathode

346
Q

Inverter

A

High speed switches that convert direct current into a series of square pulses.

347
Q

Ion chamber

A

Instrument that detects and measures the radiation intensity in areas outside of protective barriers.

348
Q

Ion pair

A

Two oppositely charged particles.

349
Q

Ion

A

Atom with too many or too few electrons; an electrically charged particle.

350
Q

Ionic bond

A

Bonding that occurs because of an electrostatic force between ions.

351
Q

Ionization potential

A

Amount of energy (34 eV) necessary to ionize tissue atoms.

352
Q

Ionization

A

Removal of an orbital electron from an atom.

353
Q

ionized

A

Referring to an atom that has an extra electron or has had an electron removed.

354
Q

Ionizing radiation

A

Radiation capable of ionization

355
Q

Irradiated

A

Referring to matter that intercepts radiation and absorbs part or all of it; exposed.

356
Q

Isobars

A

Atoms that have the same number of nucleons but different numbers of protons and neutrons.

357
Q

Isochromatid

A

Fragment in a chromosome aberration.

358
Q

Isomers

A

Atoms that have the same numbers of protons and neutrons but a different nuclear energy state.

359
Q

Isotones

A

Atoms that have the same number of neutrons.

360
Q

Isotopes

A

Atoms that have the same number of protons but a different number of neutrons.

361
Q

Isotropic

A

Equal intensity in all directions; having the same properties in a directions.

362
Q

Joule (J)

A

Unit of energy; the work done when a force of 1 N acts on an object along a distance of 1 m.

363
Q

Kerma

A

Energy absorbed per unit mass from the initial kinetic energy released in matter of all the electrons liberated by x-rays or gamma rays. Expressed in gray (Gy)

364
Q

Kilo

A

Prefix meaning “1000”

365
Q

Kilogram

A

Scientific unit of mass that is unrelated to gravitational effects; 1000g

366
Q

Kilovolt

A

Electric potential equal to 1000 V.

367
Q

Kilovolt peak

A

Measure of the maximum electrical potential across an x-ray tube; expressed in kilovolts.

368
Q

Kinetic energy

A

Energy of motion

369
Q

Latent image center

A

Sensitivity center that has many silver ions attracted to it.

370
Q

Latent image

A

Unobservable image stored in the silver halide emulsion; it is made manifest by processing.

371
Q

Latent period

A

Period after the prodromal stage of the acute radiation syndrome during which no sign of radiation sickness is apparent.

372
Q

Lateral decentering

A

Improper positioning of the grid that results in cuttoff.

373
Q

Latitude

A

Range of x-ray exposure over which a radiograph is acceptable

374
Q

Law of conservation of energy

A

Principle that states that energy may be transformed from one form to another but cannot be created or destroyed; the total amount of energy is constant.

375
Q

Law of conservation of matter

A

Principle that states that matter can be neither created nor destroyed.

376
Q

Law of inertia

A

Principle that states that a body will remain at rest or will continue to move with a constant velocity in a straight line unless acted on by an external force.

377
Q

LD 50/60

A

Dose of radiation expected to cause death within 60 days to 50% of those exposed.

378
Q

Leakage radiation

A

Secondary radiation emitted through the tube housing

379
Q

Limiting resolution

A

Spatial frequency at a modulation transfer function equal to 0.1.

380
Q

Line focus principle

A

Design incorporated into x-ray tube targets to allow a large area for heating while a small focal spot is maintained.

381
Q

Line focus

A

Projection of an inclined line onto a surface, resulting in a smaller size.

382
Q

Line pair

A

One bar and its interspace of equal width.

383
Q

Line energy transfer (LET)

A

Measure of the rate at which energy is transferred from ionizing radiation to soft tissue. Expressed in kiloelectron volts per micrometer of soft tissue.

384
Q

Linear tomography

A

Imaging modality in which the x-ray tube is mechanically attached to the image receptor and moves in one direction as the image receptor moves in the opposite direction.

385
Q

Linear, nonthreshold

A

Referring to the dose-response relationship that intersects the dose axis at or below zero.

386
Q

Linear, threshold

A

Referring to the dose-response relationship that intercepts the dose axis at a value greater than zero

387
Q

Log relative exposure (LRE)

A

change in optical density over each exposure interval.

388
Q

Long gray scale

A

Low contrast radiograph that has many shades of gray

389
Q

Look-up table

A

Matrix of data that manipulates the values of gray levels, converting an image input value to a different output value.

390
Q

Low contrast resolution

A

Ability to image objects with similar subject contrast

391
Q

Luminescence

A

Emission of visible light

392
Q

Lymphocyte

A

White blood cell that plays an active role in providing immunity for the body by producing antibodies; it is the most radio sensitive blood cell.

393
Q

Lysosome

A

Cell that contains enzymes capable of digesting cellular fragments.

394
Q

Magnetic dipole moment

A

Vector with a magnitude equal to the product of the current that flows in a loop and the area of the current loop.

395
Q

Magnetic dipole

A

Current that flows in an infinitesimally small loop.

396
Q

Magnetic domain

A

An accumulation of many atomic magnents with their dipoles aligned.

397
Q

Magnetic domain

A

An accumulation of many atomic magnets with their dipoles aligned.

398
Q

Magnetic permeability

A

Property of a material that causes it to attract the imaginary lines of the magnetic field.

399
Q

Magnetic Susceptibility

A

The ease with which a substance can be magnetized.

400
Q

Magnetism

A

The polarization of a material.

401
Q

Magnetite

A

The magnetic oxide of iron.

402
Q

Magnetization

A

Relative magnetic flux density in a materia compared with that in a vacuum.

403
Q

Magnification

A

Condition in which the images on the radiograph are larger than the object they represent.

404
Q

Magnitude

A

Number that represents a quantity.

405
Q

Main-chain scission

A

Breakage of the long chain macromolecule that divides the long, single molecule into smaller ones.

406
Q

Mainframe computer

A

A fast, medium-to- large-capacity system that has multiple microprocessors.

407
Q

Manifest image

A

The observable image that is formed when when the latent image undergoes proper chemical processing.

408
Q

Man-made radiation

A

X-rays and artificially produced radionuclides used for nuclear medicine.

409
Q

Mass density

A

Quantity of matter per unit volume.

410
Q

Mass

A

A quantity of matter; expressed in kilograms.

411
Q

Mass energy equivalence

A

Energy equals mass multiplied by the square of the speed of light.

412
Q

Matrix

A

Rows and columns of pixels displayed on a digital image.

413
Q

Matter

A

Anything that occupies space and has form or shape.

414
Q

Maximum permissible dose

A

Dose of occupational radiation that would be expected to produce no significant radiation effects. An old expression. Replaced by Dose Limit.

415
Q

Mean lethal dose

A

Constant related to the radio sensitivity of a cell.

416
Q

Mean marrow dose

A

Average radiation dose to the entire active bone marrow.

417
Q

Mean Survival Time

A

Average time between exposure and death.

418
Q

Mechanical energy

A

Ability of an object to do work.

419
Q

Meiosis

A

Process of germ cell division that reduces the chromosomes in each daughter cell to half the number of chromosomes in the parent cell.

420
Q

Metabolism

A

Anabolism and catabolism

421
Q

Metaphase

A

Phase of cell division during which the chromosomes are divisible.

422
Q

Metol

A

Secondary constituent used in the chemical composition of developing agents.

423
Q

Microcalcifications

A

Calcific deposits that appear as small grains of varying sizes on the x-ray film

424
Q

Microcomputer

A

Personal computer or electronic organizer

425
Q

Microcontroller

A

Tiny computer installed in an appliance.

426
Q

Microfocus tube

A

Tube that has a very small focal sot and that is specifically designed for imaging very small microcalcifications at relatively short source to image distances

427
Q

Milliampere (mA)

A

Measure of x-ray tube current.

428
Q

Milliampere second (mAs)

A

Product of exposure time and x-ray tube current; measure of the total number of electrons.

429
Q

Mitochondrion

A

Structure that digests macromolecules to produce energy for the cell.

430
Q

Mitosis

A

process of somatic cell division wherein a parent cell divides to form two daughter cells identical to the parent cell.

431
Q

Modem

A

Device that converts digital information into analog information.

432
Q

Modulation transfer function

A

Mathematical procedure for measuring resolution

433
Q

Modulation

A

Changing of the magnitude of a video signal; the magnitude is directly proportional to the light intensity received by the television camera tube.

434
Q

Molecule

A

Group of atoms of various elements held together by chemical forces; the smallest unit of a compound that can exist by itself and retain all its chemical properties.

435
Q

Molybdenum

A

Target material for x-ray tube s that is used in mammography.

436
Q

Momentum

A

Product of the mass of an object and its velocity.

437
Q

Monoenergetic

A

Beam that contains x-rays or gama rays that all have the same energy.

438
Q

Monosaccharide

A

A sugar

439
Q

Motherboard

A

Main circuit board in a system unit.

440
Q

Motion blur

A

Blurring of the image that results from movement of the patient or the x-ray tube during exposure.

441
Q

Moving grid

A

Grid that moves while the x-ray exposure is being made.

442
Q

National Council on Radiation Protection and Measurement

A

Organization that continuously reviews recommended dose limits.

443
Q

Natural environmental radiation

A

Naturally occurring ionizing radiation, including cosmic rays, terrestrial radiation, and internally deposited radionuclides.

444
Q

Natural magnet

A

Magnet that gets its magnetism from the Earth

445
Q

Nervous tissue

A

Tissue that consists of neurons and serves as the avenue through which electrical impulses are transmitted throughout the body for control and response.

446
Q

Neuron

A

Cell of the the nervous system that has long, thin extensions from the cell to distant parts of the body.

447
Q

Neutron

A

Uncharged elementary particle, with a mass slightly greater than that of the proton, that is found in the nucleus of every atom heavier than hydrogen.

448
Q

Newton (N)

A

Unit of force in the SI system; 1 N =0.22 lb.

449
Q

Node

A

One of many stations or terminals of a computer network.

450
Q

Noise

A

a. Grainy or uneven appearance of an image caused by an insufficient number of primary x-rays. b. uniform signal produced by scattered x-rays.

451
Q

Nonionizing radiation

A

Radiation for which the mechanism of action in tissue does not directly ionize atomic or molecular systems through a single interaction.

452
Q

Nonlinear, nonthreshold

A

Referring to varied responses that are produced from varied doses, with any dose expected to produce a response.

453
Q

Nonlinear, threshold

A

Referring to varied responses that are produced from varied doses, with a particular level below which there is no response.

454
Q

Nonstochastic effects

A

Biologic effects of ionizing radiation that demonstrate the existence of a threshold. Severity of biologic damage increases with increased dose.

455
Q

North pole

A

Magnetic pole that has a positive electrostatic charge.

456
Q

Nuclear Energy

A

Energy contained within the nucleus of an atom.

457
Q

Nucleolus

A

Rounded structure that often is attached to the nuclear membrane and controls the passage of molecules, especially RNA, from the nucleus to the cytoplasm.

458
Q

Nucleon

A

A proton or a neutron.

459
Q

Nucleotide

A

Unit formed from a nitrogenous base, a five carbon sugar molecule, and a phosphate molecule.

460
Q

Nucleus

A

a. Center of a living cell; spherical mass of protoplasm that contains the the genetic material (DNA) that is stored in its molecular structure. b. Center of an atom that contains neutrons and protons.

461
Q

Nuclide

A

General term that refers to all known isotopes, both stable and unstable, of chemical elements.

462
Q

Object plane

A

Plane in which the anatomical structures that are to be imaged lie.

463
Q

Object to image receptor distance

A

Distance from the image receptor to the object that is to be imaged.

464
Q

Occupational dose

A

Dose received by an individual in a restricted area during the course of employment in which the individual’s assigned duties involve exposure to radiation.

465
Q

Occupational exposure

A

Radiation exposure received by radiation workers.

466
Q

Off focus radiation

A

X-rays produced in the anode but not at the focal spot.

467
Q

Off level grid

A

Artifact produced by an improperly positioned radiographic tube not by an improperly positioned grid.

468
Q

Oocytes

A

Primordial follicles that grow to encapsulate oogonia.

469
Q

Opaque

A

Surface that does not allow the passage of light.

470
Q

Open filament

A

Condition that results when the filament becomes thinner and breaks.

471
Q

Operating console

A

Console that allows the radiologic technologist to control the x-ray tube current and voltage so that the useful x-ray beam is of proper quantity and quality.

472
Q

Operating system

A

Series of instructions that organizes the course of data through the computer to solve a particular problem.

473
Q

Optical density

A

Degree of blackening of a radiograph.

474
Q

Optical disc

A

Removable disc that uses laser technology to write and read data.

475
Q

Ordered pairs

A

Notation for coordinates in which the first number of the pair represents a distance along the x-axis and the second number indicates a distance up the y-axis.

476
Q

Organ system

A

Combination of tissues and organs that forms an overall integrated organization.

477
Q

Organic molecule

A

Molecule that is life supporting and contains carbon.

478
Q

Organs

A

Collection of tissues of similar structure and function.

479
Q

Origin

A

Point at which two axes meet on a graph.

480
Q

Orthochromatic

A

Referring to blue or green sensitive film; usually exposed with rare Earth screen.

481
Q

Outcome analysis

A

Image interpretation that involves reconciling the patient’s ultimate disease condition with the radiologist’s diagnosis.

482
Q

Output

A

Process of transferring the results of a computation from primary memory to storage or to the user.

483
Q

Overcoat

A

Protective covering of gelatin that encloses the emulsion.

484
Q

Overexposed

A

Referring to a radiograph that is too dark because too much x-radiation reached the image receptor.

485
Q

Oxidation

A

Reaction that reduces an electron

486
Q

Oxygen enhancement ratio

A

Ratio of the dose necessary to produce a given effect under anoxic conditions to the dose necessary to produce the same effect under aerobic conditions.

487
Q

Pair production

A

Interaction between the x-ray and the nuclear electric field that causes the x-ray to disappear and that causes two electrons–one positive and one negative–to take its place.

488
Q

Panchromatic

A

Referring to film that is sensitive to the entire visible light spectrum.

489
Q

Parallel circuit

A

Circuit that contains elements that bridge conductors rather than lie in a line along a conductor.

490
Q

Parallel grid

A

Simple grid in which all lead grid strips are parallel.

491
Q

Paramagnetic

A

Referring to materials slightly attracted to a magnet and loosely influenced by an external magnetic field.

492
Q

Parenchymal

A

Referring to part of the organ that contains tissues representative of that particular organ.

493
Q

Partial volume effect

A

Distortion of signal intensity from a tissue because it extends partially into an adjacent slice thickness.

494
Q

Particle accelerator

A

An atom “smasher.” Cyclotron. Linear Accelerator.

495
Q

Particulate radiation

A

Radiation distinct from x-rays and gamma rays; examples include alpha particles, electrons, neutrons, and protons.

496
Q

Penetrability

A

Ability of an x-ray to penetrate tissue; range in tissue; x-ray quality.

497
Q

Penetrometer

A

Aluminum step wedge

498
Q

Penumbra

A

Image blur that results from the size of the focal spot; geometric unsharpness.

499
Q

Permanent magnent

A

Magnet whose magnetism is induced artificially

500
Q

Phantom

A

Device that simulates some parameters of the human body for evaluation of imaging system performance.

501
Q

Phenidone

A

Secondary constituent in the chemical composition of developing agents.

502
Q

Phosphor

A

Active layer of the radiographic intensifying screen closest to the radiographic film.

503
Q

Phosphorescence

A

Emission of visible light during and after stimulation

504
Q

Photoconductor

A

Material that conducts electrons when illuminated.

505
Q

Photoconductor

A

Material that conducts electrons when illuminated.

506
Q

Photodiode

A

Solid state device that converts light into an electric current.

507
Q

Photodisintegration

A

Process by which very high energy x-rays can escape interaction with electrons and the nuclear electric field and can be absorbed directly by the nucleus.

508
Q

Photoelectric effect

A

Absorption of an x-ray by ionization

509
Q

photoelectron

A

Electron that has been removed during the process of photelectric absorption.

510
Q

Photoemission

A

Electron emission after light stimulation.

511
Q

Photographic effect

A

formation of the latent image.

512
Q

Photometer

A

Instrument that measures light intensity.

513
Q

Photomultiplier tube

A

Electron tube that converts visible light into an electrical signal.

514
Q

Photon

A

Electromagnetic radiation that has neither mass nor electric charge but interacts with matter as though it is a particle; x-rays and gamma rays.

515
Q

Photospot camera

A

Camera that exposes only one frame when active, receiving its image from the output phosphor of the image intenbsifier tube.

516
Q

Photostimulation

A

Emission of visible light after excitation by laser light.

517
Q

Photothermographic

A

Printing process by which film is exposed to light, thereby forming a latent image that is made visible by heat.

518
Q

Phototimer

A

Device that allows automatic exposure control.

519
Q

Pixel

A

Picture element; the cell of a digital image matrix.

520
Q

Planck’s constant

A

Fundamental physical constant that relates the energy of radiation to its frequency.

521
Q

Planetary rollers

A

Rollers positioned outside the master roller and guide shoes.

522
Q

Pluripotential stem cell

A

Stem cell that has the ability to develop into several differnt types of mature cells.

523
Q

Pocket ionization chamber (Pocket dosimeter)

A

Personnel radiation monitoring device.

524
Q

Point lesion

A

Any change that results in impairment or loss of function at the point of a single chemical bond.

525
Q

Point mutation

A

Molecular lesion caused by the change or loss of a base that destroys the triplet code and may not be reversible.

526
Q

Polarity

A

Existence of opposing negative and positive charges.

527
Q

Pole

A

Magnetically charged end of a material.

528
Q

Polyenergetic

A

Referring to radiation, such as x-rays with a spectrum of energies.

529
Q

Polysaccharide

A

Large carbohydrate that includes starches and glycogen.

530
Q

Positive beam limiting (PBL)

A

Feature of radiographic collimators that automatically adjusts the radiation field to the size of the image receptor.

531
Q

Potassium bromide

A

Compound used as a restrainer in the developer.

532
Q

Potassium iodide

A

Compound used as a restrainer in the developer

533
Q

Potential energy

A

Ability to do work by virtue of position

534
Q

Power

A

Time rate at which work (w) is done. 1 W = 1 J/s.

535
Q

Precursor cell

A

An immature cell.

536
Q

Predetector collimator

A

Collimator that restricts the x-ray beam viewed by the detector array.

537
Q

Prepatient collimator

A

Collimator that consists of several sections so that a nearly parallel x-ray beam results.

538
Q

Prereading voltmeter

A

A kVp meter that registers even though an exposure is not being made and no current is flowing within the circuit; this allows the voltage to be monitored before an exposure.

539
Q

Preservative

A

Chemical additive, usually sodium sulfide, which maintains the chemical balance of the developer and fixer.

540
Q

Preventive maintenance

A

Planned program of parts replacement at regular intervals.

541
Q

Primary coil

A

The first coildd through which the varying current in an electromagnet is passed.

542
Q

Primary protective barrier

A

Any wall to which the useful beam can be directed.

543
Q

Processing

A

Chemical treatment of the emulsion of a radiographic film to change a latent image to a manifest image.

544
Q

Processor

A

Electronic circuitry that does the actual computations and the memory that supports it.

545
Q

Prodromal period

A

First stage of the acute radiation syndrom; occurs within hours after radiation exposure.

546
Q

Prone

A

Having the front or ventral surface downward. Lying flat or prostrate.

547
Q

Proper fraction

A

Fraction in which the quotient is less than 1.

548
Q

Prophase

A

Phase of cell division during which the nucleus and the chromosomes enlarge and the DNA begins to take structural form.

549
Q

Proportion

A

The relation of one part to another.

550
Q

Proportional counter

A

Sensitive instrument that is used primarily as stationary laboratory instrument for the assay of small quantities of radioactivity.

551
Q

Protective coating

A

Layer of the radiographic intensifying screen closest to the radiographic film.

552
Q

Protective housing

A

Lead lined metal container into which the x-ray tube is fitted.

553
Q

Protein synthesis

A

Metabolic production of proteins

554
Q

Proton

A

Elementary particle with a positive electric charge equal to that of an electron and a ass approximately equal to that of a neutron. It is located within the nucleus of an atom.

555
Q

Protracted dose

A

Dose of radiation that is delivered continuously bu at a lower dose rate.

556
Q

Pulse mode/rate mode

A

Instruments designed to detect the p resence of radiation.

557
Q

Quality assurance

A

All panned and systematic actions necessary to provide adequate confidence that a facility, system, or administrative component will perform safely and satisfactorily in service to a patient. It includes scheduling, preparation, and promptness in examination or treatment, reporting of results, and quality control.

558
Q

Quality Control

A

All actions necessary to control and verify the performance of equipment; part of quality assurance.

559
Q

Quantum mottle

A

Radiographic noise produced by the random interaction of x-rays with an intensifying screen. This effect is more noticeable when very high rare Earth systems are used at a high kVP.

560
Q

Quantum theory

A

Theory in the physics of matter smaller than an atom and of electromagnetic radiation.

561
Q

Quantum

A

An x-ray photon

562
Q

Rad (radiation absorbed dose)

A

Special unit for absorbed dose and air kerma. 1 rad =100 erg/g= 0.01 Gy.

563
Q

Radiation (thermal)

A

Transfer of heat by the emission of infrared electromagnetic radiation.

564
Q

Radiation biology

A

Branch of biology that is concerned with the effects of ionizing radiation on living systems.

565
Q

Radiation exposure

A

X-ray quantity or intensity; measured in roentgens.

566
Q

Radiation fog

A

Artifact caused by unintentional exposure to radiation.

567
Q

Radiation hormesis

A

Theory that suggest that very low radiation doses may be beneficial.

568
Q

Radiation quality

A

Relative penetrability of an x-ray beam determined by its average energy; usually measured by half value layer or kilovolt peak.

569
Q

Radiation quantity

A

Intensity of radiation; usually measured in milliroentgen

570
Q

Radiation safety officer

A

That individual physician, medical physicist, or technologist assigned to develop and implement the radiation safety program.

571
Q

Radiation standards

A

Recommendations, rules, and regulations regarding permissible concentrations, as well as safe handling techniques, transportation, and industrial control of radioactive material.

572
Q

Radiation weighting factor

A

Factor used for radiation protection that accounts for differences in biologic effectiveness between different radiations Formerly called quality factor.

573
Q

Radiation

A

Energy emitted and transferred through matter.

574
Q

Radioactive decay

A

Naturally occurring process whereby an unstable atomic nucleus relieves its instaility through the emission of one or more energetic particles.

575
Q

Rad (radiation absorbed dose)

A

Special unit for absorbed dose and air kerma. 1 rad =100 erg/g= 0.01 Gy.

576
Q

Radiation (thermal)

A

Transfer of heat by the emission of infrared electromagnetic radiation.

577
Q

Radiation biology

A

Branch of biology that is concerned with the effects of ionizing radiation on living systems.

578
Q

Radiation exposure

A

X-ray quantity or intensity; measured in roentgens.

579
Q

Radiation fog

A

Artifact caused by unintentional exposure to radiation.

580
Q

Radiation hormesis

A

Theory that suggest that very low radiation doses may be beneficial.

581
Q

Radiation quality

A

Relative penetrability of an x-ray beam determined by its average energy; usually measured by half value layer or kilovolt peak.

582
Q

Radiation quantity

A

Intensity of radiation; usually measured in milliroentgen

583
Q

Radiation safety officer

A

That individual physician, medical physicist, or technologist assigned to develop and implement the radiation safety program.

584
Q

Radiation standards

A

Recommendations, rules, and regulations regarding permissible concentrations, as well as safe handling techniques, transportation, and industrial control of radioactive material.

585
Q

Radiation weighting factor

A

Factor used for radiation protection that accounts for differences in biologic effectiveness between different radiations Formerly called quality factor.

586
Q

Radiation

A

Energy emitted and transferred through matter.

587
Q

Radioactive decay

A

Naturally occurring process whereby an unstable atomic nucleus relieves its instability through the emission of one or more energetic particles.

588
Q

Radioactive disintegration

A

Process by which the nucleus spontaneously emits particles and energy and transforms itself into another atom to reach stability.

589
Q

Radioactive half life

A

Time required for a radioisotope to decay to half its original activity.

590
Q

Radioactivity

A

Rate of decay or disintegration of radioactive material. Expressed in curie or becquerel.

591
Q

Radiolysis of water

A

Dissociation of water into other molecular products as a result of irradiation.

592
Q

Radiographer

A

Radiologic technologist who deals specifically with x-ray imaging.

593
Q

Radiographic contrast

A

Combined result of image receptor contrast and subject contrast.

594
Q

Radiographic intensifying screen

A

Device that converts the energy of the x-ray beam into visible light to increase the brightness of an x-ray image.

595
Q

Radiographic noise

A

Undesirable fluctuation in the optical density of the image.

596
Q

Radiographic technique chart

A

Guide that describes standard methods for consistently producing high quality images.

597
Q

Radiographic technique

A

Combination of settings selected on the control panel of the x-ray imaging system to produce a quality image on the radiograph.

598
Q

Radiography

A

Imaging modality that uses x-ray film and usually an x-ray tube mounted from the ceiling on a track that allows the tube to be moved in any direction; provides fixed images.

599
Q

Radioisotopes

A

Radioactive atoms that have the same number of protons. They are changed into a different atomic species by disintegration of the nucleus accompanied by the emission of ionizing radiation.

600
Q

Radiological Society of North America (RSNA)

A

Scientific society of radiologists and medical physicists.

601
Q

Radiolucent

A

Referring to a tissue or material that transmits x-rays and appears dark on a radiograph.

602
Q

Radiolysis of water

A

Dissociation of water into other molecular products as a result of irradiation.

603
Q

Radiolucent

A

Referring to a tissue or material that transmits x-rays and appears bright on a radiograph.

604
Q

Radionuclides

A

Any nucleus that emits radiation.

605
Q

Radiopaque

A

Referring to a tissue or material that absorbs x-rays and appears bright on a radiograph.

606
Q

Radiosensitivity

A

Relative susceptibility of cells, tissues, and organs to the harmful action of ionizing radiation.

607
Q

Radon

A

Colorless, odorless, naturally occurring radioactive gas that decays via alpha emission and has a half life of 3.8.

608
Q

Random access memory (RAM)

A

Data that can be stored or accessed at random from anywhere in main memory in approximately equal amounts of time, regardless of where they are located.

609
Q

Rare Earth Element

A

Element that is a transitional metal found in low abundance in nature.

610
Q

Rare Earth screen

A

Radiographic intensifying screen made from rare Earth elements, which make it more useful for radiographic imaging.

611
Q

Raster Pattern

A

Pattern produced on the screen of a televsion picture tube by the movement of an electron beam or on film by a laser scan.

612
Q

Ratio

A

Mathematical relationship between similar quantities

613
Q

Read only memory

A

Data storage device that contains information supplied by the manufacturer that cannot be written on or erased.

614
Q

Real time

A

Display for which the image is continuously renewed, often to view anatomical motion, in fluoroscopy and ultrasound.

615
Q

Reciprocity law

A

Principle that states that optical density on a radiograph is proportional only to the total energy imparted to the radiographic film.

616
Q

Reconstruction time

A

Time needed for the compujter to present a digital image after an examination has been completed.

617
Q

Reconstruction

A

creation of an image from data.

618
Q

Recorded detail

A

Degree of sharpness of structural lines on a radiograph.

619
Q

Recovery

A

Repair and repopulation.

620
Q

Rectification

A

Process of converting alternating current to direct current.

621
Q

Rectifier

A

Electronic device that allows current flow in only one direction.

622
Q

Red filter

A

Filter that transmits light only above 600 nm; it is used with both green and blue senstive film

623
Q

Reducing agent

A

chemical responsible for reduction.

624
Q

Reduction

A

Process by which an electron is given up by a chemical to neutralize a positive ion.

625
Q

Reflection

A

Return or reentry of an x-ray.

626
Q

Reflection

A

Return or reentry of an x-ray.

627
Q

Refective layer

A

Layer of the intensifying screen that intercepts light headed in other directions and redirects it to the film.

628
Q

Refraction

A

Deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another.

629
Q

Region of interest (ROI)

A

Area of an anatomical structure on a reconstructed digital image as defined by the operator using a cursor.

630
Q

Relative age-response relationship

A

Increased incidence of a disease proportional to its natural incidence.

631
Q

Relative age response relationship

A

Increased incidence of a disease proportional to its natural incidence.

632
Q

Relative biologic effectiveness (RBE)

A

Ratio of the dose of standard radiation necessary to produce a given effect to the dose of test radiation needed for the same effect.

633
Q

Relative risk

A

Estimation of late radiation effects in large populations without precise knowledge of their radiation dose.

634
Q

Relay

A

Electrical device based on electromagnetic induction that serves as a switch.

635
Q

Rem (radiation equivalent man)

A

Special unit for dose equivalent and effective dose. It has been replaced by the sievert (sv) in the SI system. 1 rem =0.01Sv.

636
Q

Remnant radiation

A

X-rays that ass through the patient and interact with the image receptor.

637
Q

Replenishment

A

Replacement of developer and of fixer in the automatic processing of film.

638
Q

Resistance

A

Opposition to a force.

639
Q

Resolution

A

Measure of the ability of a system to image two separate objects and visually distinguish one from the other.

640
Q

Restrainer

A

Compound that restricts the action of the developing agent to only irradiated silver halide crystals.

641
Q

Ribonucleic acid (RNA)

A

Molecules that are involved in the growth and development of a cell through a number of small, spherical cytoplasmic organelles that attach to the endoplasmic reticulum.

642
Q

Ribosomes

A

the site of protein synthesis

643
Q

right hand rule

A

Rule by which the direction of magnetic field lines can be determined.

644
Q

Rotating anode

A

Anode used in general purpose x-ray tubes because the tubes must be capable of producing high intensity x-ray beams in a short time.

645
Q

Rotor

A

Rotating part of an electromagnetic induction motor that is located inside the glass envelope.

646
Q

Secondary protective barrier

A

Barrier designed to shield an area from secondary radiation.

647
Q

Sagittal plane

A

Any anterior posterior plane parallel to the long axis of the body.

648
Q

Saturation current

A

filament current that has risen to its maximum value because all available electrons have been used.

649
Q

Scalar

A

referring to a quantity or a measurement that has only magnitude.

650
Q

Scatter Radiation

A

X-rays scattered back in the direction of the incident x-ray beam.

651
Q

Scintillation detector

A

Instrument used in the detector arrays of many computed tomographic scanners.

652
Q

Screen lag

A

The phosphorescence in an intensifying screen.

653
Q

Screen speed

A

Relative number used to identify the efficiency of conversion of x-rays into usable light.

654
Q

Screen film

A

The most commonly used film; used with intensifying screens.

655
Q

Secondary coil

A

coil in which induced current in an electromagnet flows

656
Q

Secondary electron

A

Electron ejected from the outer shell of an atom

657
Q

Secondary memory

A

Data stored on tape drives, diskettes, and hard disc drives.

658
Q

Secondary protective barrier

A

Barrier designed to shield an area from secondary radation.

659
Q

Secondary radiation

A

leakage and scatter reaction

660
Q

Zonography

A

Thick slice tomography with a tomographic angle of less than 10 degrees`

661
Q

Y-axis

A

Vertical line of a graph

662
Q

x-ray

A

Penetrating, ionizing electromagnetic radiation that has a wavelength much shorter than that of visible light.

663
Q

x-ray tube rating charts

A

Charts that guide the technologist in the use of xray tubes.

664
Q

x-ray quantity

A

Output intensity of an x-ray imaging system; measured in roentgens (r).

665
Q

x-ray quality

A

Penetrability of an x-ray beam.

first year exit (1 decks)

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