chapter 6: qc and instrumentation artifacts

Question 1

pet qc procedure in which a source of ge68 as an external or internal rod source is placed into the bore of the gantry. data are acquired and processed to adjust the detector module gain settings

normalization
coincidence timing
energy window calibration (singles calibration)
absolute activity

Answer 1

energy window calibration (singles calibration)

Question 2

what kind of source is used for coincidence timing?

Answer 2

ge68

Question 3

this qc procedure evaluates the uniformity of each acquired sinogram and looks for modules that are not performing properly. it can use either ge68 rod sources or a phantom, and is also called the “air scan”.

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 3

blank scan

Question 3

this qc procedure often takes many hours to acquire a large number of events from each crystal, then every crystal is compared with the average performance of all detectors, and a calibration sensitivity factor is set for every detector

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 3

normalization

Question 3

this qc procedure sets uniform sensitivity of the detector modules and is similar to uniformity calibration on a gamma camera

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 3

normalization

Question 4

normalization is performed

daily
weekly
annually
after preventative maintenance and after major service

Answer 4

after preventative maintenance and after major service

Question 5

this qc procedure matches the activity measured in the dose calibrator to the activity measured in the pet scanner

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 5

absolute activity

Question 6

which qc procedure is the last of all the calibrations to be performed?

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 6

absolute activity

Question 7

which qc procedure is most important for the calculation of SUVs?

normalization
blank scan
energy window calibration (singles calibration)
absolute activity

Answer 7

absolute activity

Question 8

what type of pet scanner failure can cause changes in PMT power and drift in gains, energy window settings, and coincidence timing?

daily qc failure
energy window calibration failure
high voltage drift
failed system reboot

Answer 8

high voltage drift

Question 9

beam hardening, due to large body habitus and low kev/ma settings, on a ct scan appears as

rings
streaks
photopenic area
shading

Answer 9

streaks

Question 10

select all that apply: a pattern of concentric rings on a ct scan can be caused by

metallic implants
camera operating at lowest kev/ma setting
patient motion
detector out of adjustment
recon artifacts

Answer 10

camera operating at lowest kev/ma setting, detector out of adjustment

Question 11

patient motion causes what kind of artifact on a ct scan?

ring
streak
shading
photopenic area

Answer 11

streak

Question 12

after a patient receives a vaccine, fdg uptake will appear in the

contralateral lymph nodes near the site
ipsilateral lymph nodes near the site
focal uptake at the injection site
no fdg uptake is associated with vaccines

Answer 12

ipsilateral lymph nodes near the site

Question 13

due to the partial volume affect, lesions less than…mm in size will be falsely reduced

10 mm
20 mm
30 mm
40 mm
50 mm

Answer 13

30 mm

Question 14

a “mushroom” or “banana” artifact can be described as

false objects above the liver and spleen due to pt movement in between the ct and pet scan, appears as a falsely low region of fdg uptake

false objects above the liver and spleen due to pt movement in between the ct and pet scan, appears as a falsely high region of fdg uptake

false objects above the carina due to pt movement in between the ct and pet scan, appears as a falsely low region of fdg uptake

false objects above the carina due to pt movement in between the ct and pet scan, appears as a falsely high region of fdg uptake

Answer 14

false objects above the liver and spleen due to pt movement in between the ct and pet scan, appears as a falsely low region of fdg uptake

Question 15

an area of concentrated iv contrast that is trapped and not yet cleared from the arm vein causes…

area of decreased uptake on the pet scan
this has no effect on fdg uptake
area of increased uptake on the pet scan
variable uptake on the pet scan

Answer 15

area of increased uptake on the pet scan