Physics Comp Flashcards
(340 cards)
1
Q
The basic quantities measured in mechanics are_____,_______, and _______
A
Mass
Length
Time
2
Q
An example of a derived quantity in mechanical physics is a…
A
Volume
3
Q
What is the standard unit of mass?
A
Kilogram
4
Q
______ is a special quantity of radiologic science
A
Radioactivity
5
Q
Which system of units uses the foot, the pound, and the second?
A
English
6
Q
What is the formula for kinetic energy?
A
KE=1/2mv2
7
Q
The study of objects at rest and object in motion is the branch of physics called?
A
Mechanics
8
Q
What is the equation for velocity?
A
V=d/t
9
Q
Newton’s second law is written mathematically as?
A
F=m x a
10
Q
Momentum is a _____ quantity.
A
Derived
11
Q
Momentum is the product of the…
A
Mass of an object and its velocity
12
Q
An X-ray tube cools primarily through the process of…
A
Radiation
13
Q
The unit for work is the____
A
Joule
14
Q
_____is the kinetic energy of the random motion of molecules
A
Heat
15
Q
Thermal radiation id the transfer of heat through the emission of_____
A
Infrared radiation
16
Q
The first person to describe an element as being composed of identical atoms was…
A
John Dalton
17
Q
The smallest particle that has the properties of an element is a(n)…
A
Atom
18
Q
The periodic table of the elements was developed by_____ in the late nineteenth century.
A
Mendeleev
19
Q
Rutherford’s experiments in 1911 showed that the atom was composed of…
A
Well-defined orbits of electrons
20
Q
A positively charged nucleus surrounded by negatively charged electrons in well-defined orbits is the______model of the atom
A
Bohr
21
Q
What are the fundamental particles of an atom?
A
Proton
Electron
Neutron
22
Q
The binding energies or energy levels of electrons are represented by their____
A
Shells
23
Q
When an atom has the same number of protons, but a different number of neutrons, it is called an____
A
Isotope
24
Q
When atoms of various elements combine, they form_____
A
Molecules
25
An atom that loses or gains one or more electrons is a(n)____
Ion
26
A neutral atom has the same number of____ and electrons
Protons
27
The inner most electron shell is symbolized by the letter_____
K
28
The shell number of an atom is called the
Principle quantum number
29
Aluminum has an atomic number of 13. How many protons does it have?
13
30
Two identical atoms that exist at different energy states are called______
Isomers
31
Covalent bonding is the______
Sharing of electrons
32
During beta emission an atom releases_______
Electrons
33
The only difference between x-rays and gamma rays is their_____
Origin
34
The SI unit for dose absorbed by the patient is the_______
Gray
35
The SI unit equivalent dose relating to occupational exposure is the ________
Sievert
36
The four properties of photons are _____,_____,_____, and _______
Frequency
Wavelength
Velocity
Amplitude
37
The smallest quantity of any type of electromagnetic radiation is a(n)_______
Photon
38
What is the velocity of all electromagnetic radiation?
3 x 10^8ms
39
The rate of rise and fall of a sine wave is called its_______
Frequency
40
A hertz(Hz) is equal to_____
1 cycle per second
41
What is the electromagnetic wave equation?
C\ = wavelength x frequency
42
The__________of electromagnetic radiation is constant
Velocity
43
If the wavelength of a beam of electromagnetic radiation increases by a factor of 2, then its frequency must
Decrease by half
44
The intensity of radiation_________in_______proportion to the square of the distance of the object from the source
Decreases
| Inverse
45
The reduction of radiation intensity due to scattering and absorption is called________
Attenuation
46
The intensity of radiation on an object is reduced with distance because the radiation
Is spread out over a greater area
47
If the intensity of light from a flashlight is 4 mililumens at a distance of 3 feet, what will the intensity be at 6 feet?
1 mililumen
48
The diagnostic range of x-ray energy is
30-150 kVp
49
The energy of a photon is directly proportional to its
Frequency
50
The mass equivalent of a 100 KeV photon of radiation can be calculated using the
Relativity formula
51
X-rays are usually identified by their_______
Energy
52
The lowest energy range of the electromagnetic spectrum is
Radio waves
53
Gamma rays are produced in the_______of the atom
Nucleus
54
Photons tend to interact with matter______its wavelength
Equal in size to
55
Photons with the highest frequencies have the
Shortest wavelengths
56
The smallest unit of electrical charge is the
Electron
57
Electrification occurs through the movement of
Only electrons
58
On the surface of an electrified object the charges concentrate
On the sharpest curvatures
59
A_________ is a source of direct current
Battery
60
What is the unit of electric potential?
Volt
61
An alternating (AC) current is represented by a ________line.
Sinusoidal
62
A charged particle in motion creates a(n)
Magnetic field
63
Electric power is measured in__________
Watts
64
When a group of dipoles are aligned they create a
Magnetic domain
65
What is the SI unit of magnetic field strength?
Tesla
66
What type of material can be made magnetic when placed in an external magnetic field?
Ferromagnetic
67
Like magnetic poles________and unlike magnetic poles________
Repel
| Attract
68
Wood, glass, and plastic are_________materials
Non-magnetic
69
The magnetic intensity of an electromagnet is greatly increased by the addition of a(n)________core
Iron
70
Oersted discovered that an electric current flowing through a wire would affect a ______nearby
Compass
71
Faraday' experiments proved that a current could be induced by a magnetic field only if the field is
Changing
72
A magnet created by only a coil of wire is called a________
Solenoid
73
The magnitude of an induced current depends on the
Angle of the conductor to the magnetic field
Number of turns in the conductor
Velocity of the magnetic field as it moves past the conductor
74
Lenz's law states that an induced current flows in a direction that________ the action that produces it
Opposes
75
COMMUTATOR RING IS USED TO CHANGE________CURRENT TO________CURRENT IN AN ELECTRIC GENERATOR
ALTERNATING
| DIRECT
76
THE NUMBER OF WINDINGS ON THE PRIMARY SIDE OF A STEP-UP TRANSFORMER ARE ALWAYS________THE NUMBER OF WINDINGS ON THE SECONDARY SIDE
LESS THAN
77
MECHANICAL MOTION PRODUCES ELECTRIC CURRENT IN THE_______
Electric generator
78
A transformer has 100 coils on the primary side and 300 coils on the secondary side. What will the voltage be on the secondary side if the primary side is supplied with 120 volts
360 V
79
The current to a transformer must be supplied by a(n)
AC source
80
What is the mechanical source of energy for electrical generators that supply electricity to our cities?
Waterfalls
Steam from atomic power
Windmills
81
The three main parts of the x-ray imaging system are the X-ray tube, _______, and_______
Operating console
| High voltage generator
82
The operating console contains circuits that are
Low voltage only
83
Variations in power distribution to the x-ray machine are corrected by the
Line voltage compensator
84
The first component to receive power in the x-Ray circuit is the
Autotransformer
85
The autotransformer has_______winding(s)
One
86
The______circuit provides electrons for the X-ray tube current
Filament
87
Thermionic emission at the filament determines the______across the X-ray tube during an exposure
Milliamperage
88
A step-down transformer is located in the______circut
Filament
89
The most accurate type of timer is the______timer
Electronic
90
The automatic exposure control(AEC) terminates the exposure when
Sufficient radiation reaches the image receptor
91
The mAs timer is usually set to give the____mA at the _______time
Highest
| Shortest
92
The step-up transformer increases voltage________times
500-1000
93
A diode allows electrons to flow
From cathode to anode
94
The high voltage generator contains the high voltage transformer, the_______and the______
Filament transformer
| Rectifiers
95
The difference in the waveform between the primary and secondary sides of the high voltage transformer is the_____
Amplitude
96
In modern imaging systems, the components for rectification are
Solid state semiconductors
97
With half-wave rectification the current flows through the X-ray tube during the_____part of the cycle
Positive
98
Full-wave rectified, three-phase units provide an x-ray beam at_______per second
360 pulses
99
Voltage across the X-ray tube is most constant with
High frequency generators
100
Most mammography units operate with_____generators
High frequency
101
A single phase wave form has__________ripple
100%
102
The x-Ray beam generated by the circut with the ________voltage ripple has the________quantity and quality
Lowest
| Highest
103
The principal disadvantage of three-phase equipment is___________
Cost
104
The kVp control in the operating console controls the_______of the x-ray beam
Quality
105
The x-ray generator with the lowest power rating is the __________imaging system
Single-phase
106
What is the function of the filament
To be the source of electrons for x-ray production
107
The external structure of the X-ray tube includes the support structure, the protective housing. And the______
Glass envelope
108
The filament is made of________
Tungsten
109
The rotating anode is turned by a__________
Magnetic field
110
What percentage of the electrons in the tube current are converted to x-rays?
1%
111
The target of the rotating anode is usually coated with a___________alloy
Tungsten
112
The________is the source of radiation in the X-ray tube
Focal spot
113
Because of the line focus principle, the effective focal spot size decreases with what?
Decreasing target angle
114
The x-ray intensity is lower on the anode side of the tube because of the__________
Heel effect
115
The cathode side of the tube should be towards the________part of the patient
Thicker
116
The________is/are outside the glass envelope
Stators
117
Localized pitting or cracking on the anode can occur from
A single excessive exposure
118
Where would it be most likely to find a stationary anode tube?
Dentist office
119
What is the most common cause of tube failure?
Tungsten vaporization
120
During an exposure most of the_________energy of the projectile electrons is converted to_____.
Kinetic
| Heat
121
The useful characteristic x-rays from tungsten targets are__________x-rays
K-shell
122
Characteristic K-shell x-rays have an effective energy of_______keV
69
123
If you want the x-ray beam to consist of 100% bremsstrahlung interactions the kVp must be below________-
70 kVp
124
Characteristic x-rays are produced by
Released binding energy
125
Bremsstrahlung x-rays are produced by___________at the target
Slowing(braking) electrons
126
The_______of an x-ray beam is higher when the peak of the emission spectrum is further to the____________
Quality
| Right
127
An increase in mAs would__________the__________of the emission spectrum
Increase
| Amplitude only
128
An exposure taken at 100kVp would have a continuous emission spectrum with a minimum energy of _______keV and a maximum energy of keV
0/100
129
Most of the heat generated at the target is due to
Outer shell excitation
130
How does added filtration affect the emission spectrum
Reduced amplitude and a shift to the right
131
Roentgen/gray is the measurement for x-ray_______
Quantity
Exposure
Intensity
132
The number of useful x-rays in the beam defines x-ray
Quantity
133
X-ray quantity increases in direct proportion to increases in_______
mAs
134
A 10% increase in kVp has______effect on x-ray intensity then/as a 10% increase in mAs
Much greater
135
If x-ray quantity is doubled, the optical density on the finished radiograph will be
Increased by a factor of two
136
If a technologist changes the technique from 70 kVp at 200 mAs to 70 kVp at 400 mAs, then the x-ray intensity will______and optical density will______
Double
| Double
137
Beam quality is affected by
KVp and filtration
138
The half value layer of an x-ray beam is a measurement of beam_____________
Quality
139
If the intensity of a 70 kVp exposure at 20 mAs is 100mR, what would it be at 5 mAs?
25 mR
140
If an exposure is 75 mR at an SID of 40 inches, what would the exposure be at an SID of 72 inches?
23.1 mR
141
The penetrability of an x-ray beam is called x-ray__________
Quality
142
An x-ray beam that could pass through dense tissue would have high__________
Penetrability
| Quality
143
The main purpose of added filtration is to reduce
Patient dose
144
If the distance from the source to the image(SID) is reduced by half, how is the x-ray intensity at the image affected?
It is increased 4 times
145
An increase of 15% in kVp is equivalent to__________mAs
Doubling
146
A low quality beam would also have low
Penetrability
147
The half value layer is lowered by a decrease in
KVp
148
X-ray beam quality is improved by
Increasing filtration
149
Increasing added filtration will________beam quality and______beam quantity
Increase
| Decrease
150
A compensating filter is used to create_______optical density with a body part of __________thickness
Uniform
| Non-uniform
151
When atoms of various elements combine, they form__________
Molecules
152
During beta emission an atom releases___________
Electrons
153
The study of objects at rest and objects in motion is the branch of physics called
Mechanics
154
The unit for work is the
Joule
155
__________is the kinetic energy of the random motion of molecules
Heat
156
An X-ray tube cools primarily through the process of
Radiation
157
The smallest particle that has all the properties of an element is a(n)___________
Atom
158
The binding energies or energy levels of electrons are represented by their__________
Shells
159
When an atom has the same number of protons, but a different number of neutrons, it is called an___________
Isotope
160
The rate of rise and fall of a sine wave is called its________
Frequency
161
The ___________of electromagnetic radiation is constant
VELOCITY
162
The intensity of radiation on an object is reduced with distance because the radiation
Is spread out over a greater area
163
The energy of a photon is directly proportional to its
Frequency
164
Photons with the highest frequencies have the
Shortest wavelengths
165
What type of material can be made more magnetic when placed in an external magnetic field?
Ferromagnetic
166
Mechanical motion produces electric current in the________
Electric generator
167
When a group of dipoles are aligned they create a
Magnetic domain
168
Faraday's experiments proved that a current could be induced by a magnetic field only if the field is
Changing
169
The current to a transformer must be supplied by a(n)
AC source
170
The operating console contains circuits that are
Low voltage only
171
The high voltage generator contains the high voltage transformer, the________and the_________
Filament transformer
| Rectifiers
172
The________circuit provides electrons for the X-ray tube current
Filament
173
In modern imaging systems, the components for rectification are
Solid state semiconductors
174
Voltage across the X-ray tube is most constant with
High frequency generators
175
Most of the heat generated at the X-ray tube target is due to
Outer shell excitation
176
Because of the line focus principle, the effective focal spot size decreases with decreasing
Target angle
177
Characteristic x-rays are produced by
Released building energy
178
The________of an x-ray beam is higher when the peak of the emission spectrum is further to the_________
Quality
| Right
179
How does added filtration affect the emission spectrum?
Reduced amplitude and a shift to the right
180
Bremsstrahlung x-rays are produced by________at the target
Slowing(braking) electrons
181
The two primary forms of x-ray interaction in the diagnostic range are
Compton scattering and photoelectric absorption
182
An incident x-ray interacts with an atom without ionization during________
Coherent scattering
183
An outer-shell electron is ejected and the atom is ionized with
Compton interactions
184
Which x-ray interaction involves the ejection of an inner shell(k-shell) electron?
Photoelectric absorption
185
Compton scatter is directed at (a)__________angle from the incident beam
Any
186
As kVp_________, the probability of photoelectric absorption__________
Increases
| Decreases
187
When the mass density of the absorber is_______, it results in_______ Compton scatter
Increased
| Increased
188
Only at energies above 10MeV can______take place
Photodisintegration
189
K-shell binding energy increases with increasing___________
Atomic number
190
Which has the greatest mass density
A) fat
B) soft tissue
C) bone
D) air
Bone
191
There is complete absorption of the incident x-ray photon with
Photoelectric effect
192
Because of differential absorption, about________ of the incident beam from the X-ray tube contributes to the finished image
O.5%
193
Differential absorption is dependent on the
KVp of the exposure
Atomic number of the absorber
Mass density of the absorber
194
Attenuation is caused by
Absorption
| Scattering
195
Barium is a good contrast agent because of its
High atomic number
196
A negative contrast agent is
Air
197
X-rays transmitted without interaction contribute to
The radiographic image
198
Compton interactions, photoelectric absorption, and transmitted x-rays all contribute to_________
Differential absorption
199
High kVp techniques reduce
Patient dose
| Differential absorption
200
The use of contrast agent increases the amount of
Differential absorption
Compton scatter
Photoelectric absorption
201
The two basic components of radiographic film are the________-and the______________
Base
| Emulsion
202
A contaminant in the silver halide crystal creates the
Sensitivity speck
203
The latent image can be seen
Only after development
204
Photon interactions in the emulsion occur with exposure to___________
X-rays
| Light
205
The most commonly used radiographic film is__________
Screen-film
206
The size, shape, and distribution of silver halide crystals determine___________of screen-film
Speed
Contrast
Sensetivity
207
Spectral matching is not a consideration when using
Direct exposure film
208
What is a reasonable maximum storage time for radiographic film?
45 days
209
Film fog on unprocessed film will occur with radiation exposure as low as___________
O.2 mR
210
Storing film in very low humidity conditions can cause
Spastic artifacts
211
Manual processing of radiographs took approximately
60 minutes
212
Automatic processing reduces development time to________
22 seconds
213
What are the reducing agents in the developer
Phenidone and hydroquinone
214
The 90 second processor was made possible by what?
Polyester film base
215
Which is in the second tank in an automatic processor?
A)fixing agent
B)restrainer
C) reducing agent
D) all of the above
Fixing agent
216
Preservative is found in
The developer solution and the fixing solution
217
The temperature of the_____ is the most critical in processing film
Developer solution
218
Damp film coming out of the dryer is often caused by
Depleted glutaraldehyde
219
The thermostat must maintain temperature in the developing tank at about__________
95˚ F
220
The undeveloped silver is removed from the emulsion during___________
Fixing
221
Films can turn brown during storage due to retention of__________
Ammonium thiosulfate
222
A phosphorescent material emits light
For a period of time after stimulation
223
Luminescent materials emit light after its outer shell electrons are
Excited
224
The intensification factor is a measurement of screen________
Speed
225
The intensification factor increases with increased___________
KVp
226
A disadvantage of the speed of rare earth screens is the increase in
Quantum mottle
227
Intensifying screens wear out because of
Improper handling
228
The use of screens greatly increases
Tube life
229
In a busy department, screens should be cleaned_________
Monthly
230
An annual wire mesh test is needed to check for
Warped screens
Warped cassette fronts
Worn felt contacts
231
Which kVp selection would result in the most scattered x-rays in the image-forming beam?
90 kVp
232
The use of__________improves contrast and reduces patient dose
Collimation
233
Compton scatter contributes to
Image noise
234
The three primary factors influencing the intensity of scatter in the image-forming beam are
KVp, filed size, and patient thickness
235
Photoelectric interactions increase when_________is decreased
KVp
236
Scatter radiation increases as________increases
Field size
237
The x-rays that are transmitted through the patient without interaction contribute to__________
Useful information
238
Contrast resolution is improved by
Tight collimation
Lowering kVp
Patient compression
239
The positive beam limiting device(PBL) ensures that the x-ray beam is collimated to
The IR size
240
Lowering kVp_____patient dose and______image contrast
Increases
| Increases
241
How can you improve image contrast with a heavy patient without increasing patient dose?
Use tight collimation
242
_______is the degree of difference in optical density (OD) between areas of an image
Contrast
243
Contrast on a radiographic image is highest when the amount of_______is the lowest
Compton scatter
244
Image contrast improves when more of_________radiation is removed
Scattered
245
Grids are designed to remove scattered x-rays before they reach
The IR
246
The amount of scatter absorption in a grid depends on
The angle of the scattered photon
The height of the grid strips
The width of the interspace material
247
Grid ratio is the________of the grid strips divided by the_______ of the interspace material
Height
| Width
248
A grid with good cleanup will remove_____of the scattered x-rays
80%-90%
249
What is the grid ratio of a grid with 3mm height, 0.025mm thick lead grid strips, and 0.3mm thick interspace material?
10:1
250
The contrast improvement factor formula is
K\= contrast improvement with grid/contrast improvement without grid
251
A grid is constructed with________strips and_________interspace material
Radiopaque
| Radiolucent
252
Grids generally have a frequency of___________lines per inch
60-110
253
The main disadvantage of using parallel grids is
Grid cut-off
254
A high ratio grid is designed to be used with
High kVp techniques
255
The most critical consideration when using a crossed grid is_______
Alignment
256
The overall size and shape of a person is called the
Body habitus
257
Radiographic technique charts are based on the
Athenian patient
258
Patient thickness should be measured with the________
Caliper
259
Which tissue is most radiolucent
Lung
260
Which medical condition may require a lower technique
Emphysema
261
When only optical density needs to be changed, then only the_________should be adjusted
MAs
262
A_________increase in kVp has the same effect on optical density as doubling the mAs
15%
263
A radiograph is taken using 75 kVp @20 mAs. Which change in technique would increase contrast but maintain the same density?
A) 85 kVp @ 10 mAs
B) 85 kVp @ 40 mAs
C) 65 kVp @ 20 mAs
D) 65 kVp @ 40 mAs
65 kVp @ 40 mAs
264
A radiograph is taken using 65kVp @ 10 mAs is too light. Which technique would double the optical density while producing a wider scale of contrast?
A)75 kVp @ 10 mAs
B) 75 kVp @ 20 mAs
C) 55 kVp @ 20 mAs
D) 55 kVp @ 40 mAs
75 kVp @ 10 mAs
265
How could contrast be improved on a bedside radiograph of a very large patient?
Use a grid
Lower kVp
Use tight collimation
266
Sharpness of detail can be improved by increasing________
SID
267
In a variable kVp technique chart, the optimal mAs is set for each body part, and there is a _______kVp increase for each centimeter of thickness
2
268
The technique chart most commonly used is the_______kVp chart
Fixed
269
The benefit of the fixed kVp chart is
Lower patient dose
270
The most important part of using automatic exposure control is
Patient positioning
271
an increase in________will increase both beam quality and beam quantity
KVp
272
What are the four primary exposure factors?
KVp, mA, time and SID
273
Changes in kVp affect
Optical density
Image contrast
Image noise
274
An increase in mAs causes (an)_______in beam quality and (an)_________in beam quantity
No change
| Increase
275
There is a direct relationship between the quantity of x-rays and the_______
Milliamperage
276
If mAs is increased from 20 mAs to 40 mAs, the patient dose will
Be doubled
277
Beam penetrability is increased if_______is increased
KVp
278
Beam quality is improved when the______is increased, but_______has no effect on beam quality
KVp
| MA
279
Which technique would be best for reducing image blur?
A) 90 kVp/200 mA @ .01sec
B) 85 kVp/200 mA @ .02sec
C) 75 kVp/400 mA @ .02sec
D) 65 kVp/400 mA @ .04sec
90 kVp/200 mA @ .01sec
280
Which technique would give the highest patient dose?
A) 90 kVp/200 mA @ .02sec
B) 87 kVp/400 mA @ .02sec
C) 74 kVp/400 mA @ .04sec
D) 65 kVp/300 mA @ .1sec
65 kVp/300 mA @.1sec
281
Select the imaging system that provides the highest beam quantity and quality
High frequency
282
Added filtration has the effect of_______the beam quality and_______patient dose.
Increasing
| Reducing
283
All general purpose tubes have________ AL equivalent INHERENT filtration
O.5mm
284
Filtration is ADDED to x-ray machines so that the required total of________mm AL equivalent filtration is achieved
2.5
285
The large focal spot CAN provide a beam of
Higher quantity and unchanged quality
286
A high quality radiograph should always demonstrate
A) structures and tissues
B) high contrast
C) minimum magnification
D) all of the above
Structures and tissues
287
Spatial resolution improves with decreased
A) screen blu
B) motion blur
C) geometric blur
D) all of the above
All of the above
288
_________ is defined as the ability to image two separate objects and visually detect one from the other
Resolution
289
Radiographic_________is random fluctuation in the optical density of a radiograph
Noise
290
Higher speed image receptors generally produce images with
Increased noise
291
The slope of the _______portion of the characteristic curve shows the film contrast
Straight line
292
In general radiography, the useful optical densities lie between____________and__________
0. 25
| 2. 25
293
The inherent base density plus fog density in film is_______
0.1-0.3
294
What is the formula for optical density?
OD\= log10(lo/lt)
295
If 10% of the view box light is transmitted through an area of film, what is the optical density in that area?
1
296
The densities above 2.5 on a film are represented in the________portion of the characteristic curve
Shoulder
297
A film with a characteristic curve showing a high slope would be useful when______is needed
High contrast
298
The base + fog of a film is shown below the________of the characteristic curve
Toe portion
299
An image receptor with_______can be used over a greater range of exposures
Wide latitude
300
The three primary geometric factors affecting image quality are
Magnification, distortion, and focal spot blur
301
What is the formula for the magnification factor?
MF\= SID/SOD
302
The best way to minimize magnification is to use a
Long SID and a small OID
303
Focal spot blur can be reduced by using a
Small focal spot
304
Subject contrast is affected by
Patient thickness
305
Distortion can be reduced by
Placing the object plane parallel to the image plane
306
Which of these body parts has the highest subject contrast?
A)abdomen
B) skull
C) chest
D) pelvis
Chest
307
Radiographic image quality is improved when the_______is increased
SID
308
Patient thickness affects image quality by affecting
Magnification
Radiographic contrast
Focal spot blur
309
The technologist primarily controls radiographic contrast by varying the
Kv
310
Optical density is directly controlled by changing the______
mAs
311
What is the name of an image constructed from numerical information?
Digital image
312
Subtraction, contrast enhancement, and edge enhancement are known as:
Post processing techniques
313
What is the display of the digital image that occurs in a series of rows and columns called?
Matrix
314
What is the matrix of the digital image composed of?
Pixels
315
Where is the latent image in computed radiography formed?
In the photostimulable phosphor
316
The ratio of image to object as a function of spatial resolution (lp/mm) is known as
Modulation transfer function
317
What type of laser is used to release the energy stored in the CR phosphor?
Helium-neon
318
Before being reused, the CR imaging plate is:
Exposed to intense light
319
Which imaging method requires the shortest time from exposure to image viewing?
DR
320
The mathematical formulas used for digital image reconstruction of specific exams are known as:
Processing algorithms
321
What is the technique used to remove superimposed structures to improve the visibility of anatomic structures?
Subtraction
322
__________is the alteration of pixel values so that they demonstrate different brightness levels?
Contrast enhancement
323
___________is the alteration of the image to improve the visibility of small high-contrast structures
Edge enhancement
324
Which factor sets the midpoint of the densities visible on the display monitor?
Window level
325
Which factor corresponds to the contrast of the radiographic image on the display monitor?
Window width
326
Which of the following systems is not a type of direct readout digital radiography?
A) flat panel direct conversion
B) charge-coupled device
C) flat panel indirect conversion
D) computer radiography
Computed radiography
327
The matrix of data that manipulates the values of gray levels is known as
Look up tables
328
A significant advantage of digital compared to film-screen radiography is:
Post processing image enhancement
329
Which of the following matrix sizes would have the best image quality?
A) 64 x 64
B) 256 x 256
C) 1024 x 1024
D) 2048 x 2048
2048 x 2048
330
The pixel bit depth determines the amount of shades of gray the system is capable of displaying on the digital image
True or false
True
331
The "S" value is used to represent
Exposure index
332
The graphic display of the distribution of pixel values for each individual image is known as the:
Histogram
333
The overall efficiency of converting the information from x-ray intensities into an image is known as:
Detective quantum efficiency
334
A low exposure would result in a low calculated "S" number
True or false
False
335
The RIS communicates with PACS via DICOM; while HIS communicates with PACS via HL7
True or false
True
336
In a CR system, spatial resolution is controlled by:
```
A) detector element size
B) sampling frequency
C) matrix size of display monitor
D) both B and C
E) both A and C
```
Both B and C
337
In a DR imaging system, spatial resolution is controlled by:
```
A)detector element size
B) sampling frequency
C) matrix size of display monitor
D) both A and C
E) both b and C
```
Both A and C
338
When exposure signal decreases and quantum mottle increases the __________
Signal to noise ratio decreases
339
When a CR imaging plate is improperly erased__________can happen in the radiographic image
Ghosting
340
Banding artifact in a digital image is the result of:
Digital processor malfunction
