Deck 10: Radiation Dose in Computed Tomography

Question 1

What is/are the unit(s) of absorbed dose? I. rad (r)
II) gray (Gy)
III) Sievert (Sv)

A)I and II
B)II and III
C)I and III
D)I, II, and III

Answer 1

I and II

Question 2

Examples of stochastic effects include: I. cancer
II) leukemia
III) hereditary effects

A)I and II
B)II and III
C)I and III
D)I, II, and III

Answer 2

I, II, and III

Question 3

The old unit of effective dose was the rad.

Answer 3

False

Question 4

The radiation quantity exposure refers to the concentration of radiation at a particular point on the patient.

Question 5

What is used to measure exposure?

A)Geiger counter
B)ionization chamber
C)detector chamber
D)scintillation detector

Question 6

The computed tomography dose index was developed by the U.S. Food and Drug Administration.

Question 7

Examples of deterministic effects include: I. skin erythema
II) epilation
III) cataracts

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 8

Deterministic effects follow a:

A)linear dose
B)nonlinear dose
C)threshold dose
D)nonthreshold dose

Question 9

What is used to quantify the risk from partial body exposure to that from an equivalent whole body dose?

A)quantity effective dose
B)quantity absorbed dose
C)absorbed dose
D)entrance dose

Question 10

Stochastic effects are those effects for which the probability of the effect occurring depends on the dose.

Question 11

What is the dose limit for radiation workers in the United States?

A)20 mSv/year
B)50 mSv/year
C)75 mSv/year
D)100 mSv/year

Question 12

The measured radiation dose is inversely proportional to the number of detector rows.

Question 13

The dose-length product is directly proportional to the scan length.

Question 14

Factors directly affecting computed tomography dose cannot be controlled by the technologist.

Question 15

The method suggested by the Center for Devices and Radiological Health for computed tomography dose measurement is the pencil ionization chamber.

Question 16

What is/are the unit(s) of exposure? I. Roentgen (R)
II) Sievert (Sv)
III) coulomb per kilogram (C/kg)

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 17

What is the amount of energy absorbed per unit mass of material? I. rad
II) absorbed dose
III) radiation dose

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 18

Radiation bioeffects are classified as: I. stochastic
II) deterministic
III) nonstochastic

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 19

What dose-response model is a radiation risk model most favored by radiobiologists in estimating the risk of exposure in radiology?

A)linear threshold
B)linear nonthreshold
C)nonlinear threshold
D)nonlinear nonthreshold

Question 20

Phantoms are not used for the process of computed tomography dose measurement.

Question 21

What is the easiest and probably the most accurate method used to report dose?

A)thermoluminescent dosimeter
B)film dosimeter
C)ionization chamber
D)Geiger counter

Question 22

What was the first dose descriptor to be identified?

A)dose profile
B)computed tomography dose index
C)multiple-scan average dose
D)multiscan peak dose

Question 23

Effective mAs can be described as:

A)effective mAs = kilovolts/pitch
B)effective mAs = true mAs + pitch
C)effective mAs = true mAs/pitch
D)effective mAs = pitch/kilovolts

Question 24

The overall goals of automatic tube current modulation are to: I. provide consistent image quality
II) increase scan speed
III) control dose to the patient

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 25

Which of the following are factors of dose that can be controlled by the technologist? I. technique factors
II) patient centering
III) x-ray beam collimation

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 26

What is the unit of the computed tomography dose index?

A)gray
B)Roentgen
C)rem
D)seivert

Question 27

What instrument is used to measure the charge removed from the ionization chamber?

A)absorptometer
B)thermometer
C)electrometer
D)dosimeter

Question 28

What term is used to refer to the size and shape of the beam emanating from the x-ray tube and passing through the patient?

A)fan beam
B)cone beam
C)beam geometry
D)cone geometry

Question 29

What types of dosimeters have previously been used to measure dose in computed tomography? I. film dosimeter
II) thermoluminescent dosimeter
III) ionization chamber

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 30

What is the process by which additional rotations before and after the planned length are taken? I. overranging
II) doubling scan
III) z-overscanning

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 31

What term refers to the automatic control of the milliamperage in two directions during data acquisition by specific technical procedures?

A)automatic tube current modulation
B)automatic exposure control
C)miscentering
D)miscentering..

Question 32

What technical factor determines the penetrating power of the photons coming from the x-ray tube?

A)kVp
B)mA
C)seconds
D)mAs

Question 33

Which of the following are recommended by the Center for Devices and Radiological Health as computed tomography dose descriptors? I. computed tomography dose index
II) multiple-scan average dose
III) dose profile

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 34

What is the term used to describe the instrumentation and methods used to measure patient dose from a computed tomography scanner?

A)computed tomography dosimetry
B)computed tomography absorptiometry
C)radiation intensity
D)dose distribution

Question 35

What is/are the purpose(s) of the use of bowtie filters in computed tomography? I. shape the beam intensity
II) produce a more uniform beam
III) increase scan time

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 36

Which technique factor determines the quantity of photons (dose) incident on the patient for the duration of the exposure?

A)kV
B)mA
C)seconds
D)mAs

Question 37

What dose descriptor is used to describe a measurement of the total amount of exposure for a series of scans?

A)computed tomography dose index volume
B)dose-length product
C)multiple-scan average dose
D)single-scan peak dose

Question 38

Which factors affecting dose in computed tomography have a direct influence on image quality but no direct effect on radiation dose?

A)direct
B)indirect
C)proportional
D)nonproportional

Question 39

What is the term used to describe a ratio of the difference the table travels per revolution to nominal beam collimation?

A)dose-length product
B)pitch
C)scan ratio
D)tilt ratio

Question 40

If the pitch increases, the dose:

A)decreases
B)increases
C)stays the same
D)pitch and dose are unrelated

Question 41

Please match the following units of dose measurement. All answer selections will be used just once.

rad

A)old unit of effective dose
B)conventional unit of exposure
C)old unit of absorbed dose
D)SI unit of effective dose
E)SI unit of absorbed dose

Question 42

Please match the following units of dose measurement. All answer selections will be used just once.

gray

A)old unit of effective dose
B)conventional unit of exposure
C)old unit of absorbed dose
D)SI unit of effective dose
E)SI unit of absorbed dose

Question 43

Please match the following units of dose measurement. All answer selections will be used just once.

Sievert

A)old unit of effective dose
B)conventional unit of exposure
C)old unit of absorbed dose
D)SI unit of effective dose
E)SI unit of absorbed dose

Question 44

Please match the following units of dose measurement. All answer selections will be used just once.

Roentgen

A)old unit of effective dose
B)conventional unit of exposure
C)old unit of absorbed dose
D)SI unit of effective dose
E)SI unit of absorbed dose

Question 45

Radiation protection actions include: I. decrease exposure time
II) increase distance
III) increase shielding

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 46

The principle of _____________ refers to the reduction of the radiation dose while maintaining the required image quality needed for making a diagnosis.

A)ALARA
B)collimation
C)optimization
D)shielding

Question 47

Radiation protection principles include: I. justification
II) optimization
III) dose limitation

A)I and II
B)II and III
C)I and III
D)I, II, and III

Question 48

Please match the following units of dose measurement. All answer selections will be used just once.

rem

A)old unit of effective dose
B)conventional unit of exposure
C)old unit of absorbed dose
D)SI unit of effective dose
E)SI unit of absorbed dose

Question 49

What provides the most comprehensive approach to computed tomography dose reduction?

A)longitudinal tube current module
B)angular tube current module
C)angular-longitudinal tube current module
D)uniform tube current modulation