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Flashcards in Physics Comp Deck (340)
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1

The basic quantities measured in mechanics are_____,_______, and _______

Mass
Length
Time

2

An example of a derived quantity in mechanical physics is a...

Volume

3

What is the standard unit of mass?

Kilogram

4

______ is a special quantity of radiologic science

Radioactivity

5

Which system of units uses the foot, the pound, and the second?

English

6

What is the formula for kinetic energy?

KE=1/2mv2

7

The study of objects at rest and object in motion is the branch of physics called?

Mechanics

8

What is the equation for velocity?

V=d/t

9

Newton's second law is written mathematically as?

F=m x a

10

Momentum is a _____ quantity.

Derived

11

Momentum is the product of the...

Mass of an object and its velocity

12

An X-ray tube cools primarily through the process of...

Radiation

13

The unit for work is the____

Joule

14

_____is the kinetic energy of the random motion of molecules

Heat

15

Thermal radiation id the transfer of heat through the emission of_____

Infrared radiation

16

The first person to describe an element as being composed of identical atoms was...

John Dalton

17

The smallest particle that has the properties of an element is a(n)...

Atom

18

The periodic table of the elements was developed by_____ in the late nineteenth century.

Mendeleev

19

Rutherford's experiments in 1911 showed that the atom was composed of...

Well-defined orbits of electrons

20

A positively charged nucleus surrounded by negatively charged electrons in well-defined orbits is the______model of the atom

Bohr

21

What are the fundamental particles of an atom?

Proton
Electron
Neutron

22

The binding energies or energy levels of electrons are represented by their____

Shells

23

When an atom has the same number of protons, but a different number of neutrons, it is called an____

Isotope

24

When atoms of various elements combine, they form_____

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