Deck 11: Instrumentation

Question 1

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

Answer 1

Ionization chamber

Question 2

The gas in a dose calibrator is usually

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

Answer 2

argon.

Question 3

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 3

chi-square test.

Question 4

Quenching gas is used in a(n)

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

Question 5

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 6

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 7

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 8

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

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

Question 9

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 10

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 11

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 12

A PHA includes all of the following EXCEPT

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

Question 13

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

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

Question 14

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

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

Question 15

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 16

Extrinsic spatial resolution is monitored using

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

Question 17

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 18

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.

Question 19

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 20

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 21

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 22

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 23

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 24

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.

Question 25

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 26

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 27

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 28

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 29

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 30

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

Question 31

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 32

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 33

Ramp-filtered projections are characterized by

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

Question 34

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 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

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 37

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 38

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 39

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

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