Deck 11: Instrumentation

Question 1

The gas in a dose calibrator is usually

A) air.
B) helium.
C) argon.
D) quenching.

Answer 1

argon.

Question 2

When performing quality control on a well counter or thyroid probe, constancy is tested by performing a(n)

A) chi-square test.
B) FWHM.
C) intrinsic resolution check.
D) count for each radionuclide used.

Answer 2

chi-square test.

Question 3

Geometric efficiency is defined

A) as the ratio of the number of detected events to the number of source emissions.
B) as the fraction of emitted photons (gamma or x-rays) that hit the detector; it depends on the detector configuration and its distance from the source.
C) as the fraction of gamma rays that are detected when they hit the detector; it depends on the thickness (t) and attenuation coefficient ( $\mu$ ) of the detecting material.
D) as the amount of blurring that is produced by an imaging system, characterized by point spread function and line spread function.

Answer 3

as the fraction of emitted photons (gamma or x-rays) that hit the detector; it depends on the detector configuration and its distance from the source.

Question 4

Which survey meter is appropriate to use when measuring high levels of radiation?

A) Ionization chamber
B) Dose calibrator
C) GM meter
D) Body badge

Question 5

Quenching gas is used in a(n)

A) dose calibrator.
B) Geiger-Mueller (GM) detector.
C) ionization chamber.
D) pocket dosimeter.

Question 6

A PHA includes all of the following EXCEPT

A) lower-level discriminator.
B) upper-level discriminator.
C) anticoincidence circuit.
D) amplifier.

Question 7

In a scintillation camera, geometric resolution depends on

A) the size of the patient.
B) the position of the source.
C) the configuration of the holes in a collimator.
D) filtering the image.

Question 8

For a parallel-hole collimator, spatial resolution degrades as

A) the source-to-collimator distance increases.
B) the source-to-collimator distance decreases.
C) the collimator holes decrease in size.
D) the collimator holes increase in number.

Question 9

When performing quality control on a dose calibrator, it is required that the accuracy test is performed

A) daily.
B) quarterly.
C) annually.
D) at installation.

Question 10

Extrinsic spatial resolution is monitored using

A) FWHM.
B) quadrant bar phantom.
C) flat field collimator.
D) electronic zoom.

Question 11

The percent full width at half maximum (FWHM) is often used as a measure of

A) precision.
B) sensitivity.
C) intensity.
D) resolution.

Question 12

The anticoincidence component on a pulse-height analyzer determines if

A) more than one photon at the same energy is counted.
B) two photons are counted at the same time.
C) the lower discriminator is triggered, but not the upper energy discriminator.
D) the upper and lower energy discriminators are triggered simultaneously.

Question 13

Spatial resolution is defined as

A) the ratio of the number of detected events to the number of source emissions.
B) geometric efficiency and is defined as the fraction of emitted photons (gamma or x-rays) that hit the detector; it depends on the detector configuration and its distance from the source.
C) the fraction of gamma rays that are detected when they hit the detector; it depends on the thickness (t) and attenuation coefficient ( $\mu$ ) of the detecting material.
D) the amount of blurring that is produced by an imaging system characterized by point spread function and line spread function.

Question 14

Which detector is confined for use in detecting radiation where the exposure levels are below 2000 mR/hr?

A) Ionization chamber
B) Dose calibrator
C) GM meter
D) Body badge

Question 15

When performing quality control on a well counter or thyroid probe, energy resolution is evaluated

A) weekly.
B) monthly.
C) quarterly.
D) annually.

Question 16

When performing quality control on a dose calibrator, it is recommended to test geometry:

A) daily.
B) quarterly.
C) annually.
D) at installation.

Question 17

Detector efficiency is defined as

A) the ratio of the number of detected events to the number of source emissions.
B) the geometric efficiency and is defined as the fraction of emitted photons (gamma or x-rays) that hit the detector; it depends on the detector configuration and its distance from the source.
C) the fraction of gamma rays that are detected when they hit the detector; it depends on the thickness (t) and attenuation coefficient ( $\mu$ ) of the detecting material.
D) the amount of blurring that is produced by an imaging system, characterized by point spread function and line spread function.

Question 18

When performing quality control on a dose calibrator, the testing of the correct activity over the entire range of radioactivity used in the laboratory is the

A) accuracy test.
B) geometry test.
C) linearity test.
D) constancy test.

Question 19

Intrinsic efficiency is defined as

A) the ratio of the number of detected events to the number of source emissions.
B) geometric efficiency and is defined as the fraction of emitted photons (gamma or x-rays) that hit the detector; it depends on the detector configuration and its distance from the source.
C) the fraction of gamma rays that are detected when they hit the detector; it depends on the thickness (t) and attenuation coefficient ( $\mu$ ) of the detecting material.
D) the amount of blurring that is produced by an imaging system characterized by point spread function and line spread function.

Question 20

When performing quality control on a dose calibrator, it is required that the constancy test is performed

A) daily.
B) quarterly.
C) annually.
D) at installation.

Question 21

When referring to image quality, resolution

A) refers to how well objects can be separated in space.
B) determines whether two objects have different activity concentrations.
C) refers to the ability to see the edge of a structure.
D) occurs because of the random nature of counting statistics.

Question 22

In general, the pixel size should be less than:

A) one-quarter the system resolution.
B) one-third the system resolution.
C) one-quarter the system efficiency.
D) one-third the system efficiency.

Question 23

Increased sensitivity for SPECT imaging can be achieved by using a

A) general-purpose collimator.
B) converging collimator.
C) high-energy collimator.
D) high-resolution collimator.

Question 24

Ramp-filtered projections are characterized by

A) a star artifact.
B) edge information enhancement.
C) smoothing of edge information.
D) enhancing noise.

Question 25

In SPECT/CT imaging, it is best if the patient does shallow breathing throughout the scan.

Question 26

Body contouring or elliptical orbits in SPECT imaging have an advantage over circular orbits because they

A) improve the accuracy of gantry location.
B) reduce the camera-to-patient distance.
C) maximize resolution.
D) minimize noise.

Question 27

In multihole low-energy collimators, longer and smaller holes produce

A) better uniformity.
B) better sensitivity.
C) better intrinsic resolution.
D) better spatial resolution.

Question 28

When the same nonuniformity is back-projected at each of the angles of acquisition, the result is

A) blurring.
B) a star artifact.
C) a ring artifact.
D) streak artifact.

Question 29

The center-of-rotation measurement

A) determines the number of projections.
B) corresponds to the pixel size at the center of the orbit.
C) corresponds to the radius.
D) determines the offset between the camera center and projections.

Question 30

In the reconstruction of SPECT images, segmenting refers to

A) volume rendering.
B) determining the number of counts per pixel.
C) separating the organ from the background or nearby structures.
D) dividing an organ into different components.

Question 31

A low-pass filter

A) allows low frequencies to pass and blocks high frequencies.
B) blocks low frequencies and allows high frequencies to pass.
C) smoothes images by reducing low frequencies.
D) reduces noise by blocking low frequencies.

Question 32

Compared to a low-energy collimator, a high-energy collimator will have all of the following EXCEPT

A) thicker septa.
B) longer holes.
C) lower resolution.
D) higher sensitivity.

Question 33

When referring to image quality, contrast

A) refers to how well objects can be separated in space.
B) determines whether two objects have different activity concentrations.
C) refers to the ability to see the edge of a structure.
D) occurs because of the random nature of counting statistics.

Question 34

According to the Nuclear Regulatory Commission (NRC), survey meters must be calibrated:

A) daily.
B) monthly.
C) quarterly.
D) annually.

Question 35

Digitization of the signal of each photomultiplier tube (PMT)

A) increases sensitivity.
B) decreases scan time.
C) increases contrast.
D) increases processing flexibility.

Question 36

The 360-degree orbit is most often used in SPECT studies EXCEPT for scans of

A) the brain.
B) the heart.
C) the liver.
D) bone.

Question 37

The devices that operate in the saturation range include all of the following EXCEPT

A) dose calibrator.
B) ionization chamber.
C) personnel dosimeters.
D) Geiger-Mueller counter.

Question 38

If a detector can produce an electronic signal for each individual interaction whose amplitude reflects the amount of energy absorbed, it is said to have spatial resolution.

Question 39

Quench gas is used in a Geiger-Mueller counter to

A) enhance ionizations.
B) stop the discharge.
C) alter the voltage.
D) improve the counting of alphas.