Deck 13: Pet Instrumentation

Question 1

A true coincidence event occurs when

A)a pair of annihilation gamma rays strike two detectors at the same time.
B)a pair of annihilation gamma rays strike one detector at the same time.
C)photons from two different annihilation events are detected at the same time.
D)photons from two different annihilation events collide, resulting in a third annihilation event.

Answer 1

a pair of annihilation gamma rays strike two detectors at the same time.

Question 2

With PET radionuclides, the higher the energy particle,

A)the greater the mean range for the travel of the positron.
B)the shorter the mean range for the travel of the positron.
C)won't have an effect on the mean range for the travel of the positron.
D)it reduces the mean range for the travel of the positron.

Answer 2

the greater the mean range for the travel of the positron.

Question 3

In PET scanners with a "reflective block of crystals" design, reflective material surrounds

A)each crystal.
B)every other crystal.
C)every block of crystals.
D)every ring of crystals.

Answer 3

each crystal.

Question 4

In PET reconstruction, filtered back-projection

A)creates streak or star artifacts.
B)eliminates streak or star artifacts.
C)increases contrast in the image.
D)equates with iterative reconstruction.

Question 5

In a dedicated PET scanner, there is a photomultiplier tube (PMT) for

A)each crystal.
B)every other crystal.
C)a group of crystals.
D)every ring in crystals.

Question 6

All of the following have been used as crystals for PET imaging EXCEPT

A)BGO.
B)LSO.
C)LYSO.
D)YBGO.

Question 7

Whole-body imaging with a scanner in 3D mode can result in

A)decreased need for correction techniques.
B)increased pyramidal-shaped sensitivity.
C)reduced reconstruction time.
D)an increase in acquisition time.

Question 8

In PET imaging, a large particle range results in

A)better resolution of annihilation events.
B)an overcalculation of the annihilation event from the positron-emitting atom.
C)a slight mispositioning of the annihilation event from the positron-emitting atom.
D)truer positioning of the annihilation event with the positron-emitting atom.

Question 9

In comparing PET myocardial imaging to SPECT myocardial imaging for myocardial disease, PET demonstrates

A)increased resolution, decreased sensitivity, and increased specificity.
B)decreased resolution, increased sensitivity, and increased specificity.
C)increased resolution, increased sensitivity, and increased specificity.
D)decreased resolution, increased sensitivity, and decreased specificity.

Question 10

When performing 3D imaging

A)scatter correction is important.
B)photon scatter is not a problem.
C)hot organs near the FOV do not pose a problem.
D)2D images are converted to 3D images electronically.

Question 11

Spatial resolution on PET scanners is determined primarily by

A)the collimator used and the size of the septa.
B)the size of the crystals and their separation.
C)the sensitivity of the system and the number of rings.
D)the scatter correction and the accuracy of the attenuation correction.

Question 12

The production of a single PET radiopharmaceutical requires all of the following EXCEPT

A)a cyclotron.
B)a target.
C)a hot cell.
D)a collimator.

Question 13

Whole body imaging in PET scans typically covers imaging

A)from head to toe.
B)from the hips through the base of the brain.
C)from the knees through the base of the brain.
D)from the knees to the head.

Question 14

On a PET sinogram, the horizontal row represents

A)each angle from which the projection was taken.
B)the count profile across the distance of the gantry as seen from each angle.
C)the set of reconstructed transaxial slices as seen from each angle.
D)the angle from which the projection is taken over 180 degrees.

Question 15

The line of response (LOR)

A)is determined for each crystal within a detector system.
B)is determined for each detector system and each crystal type.
C)is created by the detection of an annihilation photon pair by opposing crystals.
D)is created to perform scatter correction techniques.

Question 16

In a PET scanner, the determination of the annihilation event is made possible by

A)electronic collimation.
B)parallel hole collimation.
C)back-scatter projection.
D)filtered back-scatter projection.

Question 17

Characteristics of the bismuth germinate crystal include that fact that it

A)is a fast scintillator.
B)yields more light than an NaI (Tl) crystal.
C)is very good at stopping 511-keV photons.
D)has excellent energy resolution.

Question 18

The BGO crystal

A)is efficient at rejecting scatter photons because of its narrow window.
B)is efficient at rejecting scatter photons because of its wide window.
C)is not efficient at rejecting scatter photons because of its narrow window.
D)is not efficient at rejecting scatter photons because of its wide window.

Question 19

Rubidium-82 is an analog to

A)calcium.
B)potassium.
C)sodium.
D)glucose.

Question 20

Regarding septa on a PET system, all of the following are true EXCEPT

A)they limit the field of view of events to those within the same detector ring, or events with contiguous planes.
B)they reduce the number of scatter and random events from outside the plane.
C)they allow for the system to operate in 2D mode.
D)they allow for the system to operate in 3D mode.

Question 21

Absolute activity calibrations should be performed after a major service, as well as

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

Question 22

In a PET system, gain update calibration should be performed at least

A)weekly.
B)quarterly.
C)annually.
D)following repair.

Question 23

In PET imaging, the purpose of a transmission scan is

A)for quality control purposes.
B)to compensate for the variable attenuation in tissues.
C)for registration purposes.
D)to provide data for scatter correction.

Question 24

When compared to non-time of flight (ToF) scanners, ToF scanners

A)have a decreased resolution for small lesions.
B)require a longer acquisition time.
C)do not have a full LOR across the FOV.
D)have decreased image quality.

Question 25

In a PET system, energy window calibration is typically performed after repair as well as

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

Question 26

In PET imaging, blank scans are used

A)to subtract background.
B)to calculate scatter correction.
C)to determine deadtime.
D)in attenuation correction.

Question 27

The standard uptake value is useful in

A)performing attenuation correction.
B)calculating scatter correction.
C)differentiating between malignant and benign tissue.
D)determining the time span between injection and scan.

Question 28

In PET reconstructions, OSEM and RAMLA are most commonly used over FBP because

A)they are faster with less data storage.
B)of reduced streak artifacts and image noise.
C)of increased image contrast.
D)of fewer mispositioning artifacts.

Question 29

In PET scanning, blank scans are performed

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