Instrument Operations and Quality control

Question 1

With a matrix size of 64X64 and two sources placed 30 cm apart, there are 44 Pixels between the activity peaks on the generated activity profile. What is the pixel size?
a) 6.8cm/pixel
b) 6.8mm/pixel
c) 1.4mm/pixel
d) 0.14cm/pixel

Answer 1

b) 6.8mm/pixel

Question 2

If the distance between two point sources placed on the camera surface is 35 cm in both the X and Y directions and the number of pixels between their activity profile peaks is 52 on the X-axis and 55 on the Y-axis, are the pixel dimensions in the X and Y direction within 0.5mm of one another?
a) Yes
b) No

Answer 2

a) Yes

Question 3

Of the following types of transmission phantoms, which one requires the fewest images to test the spatial resolution over the entire detector face?
a) Hine-Duley phantom
b) Four-quadrant bar phantom
c) Parallel-line equal-space phantom
d) Orthogonal-hole phantom

Answer 3

d) Orthogonal-hole phantom

Question 4

Select two reasons that metal implants in patients create problems for SPECT/CT and PET/CT systems.?
a) The additional weight of the patient may exceed the table’s load limit
b) High CT numbers from metal overestimate the attenuation that photons emitted by RPH will experience.
c) Artifacts in CT images due to the presence of metal may propagate to attenuation maps
d)Metal disturbs the magnetic field of CT

Answer 4

b) High CT numbers from metal overestimate the attenuation that photons emitted by RPH will experience
c) Artifacts in CT images due to the presence of metal may propagate to attenuation maps

Question 5

What types of QC are usually done for Well counters?
a) Linearity
b) Consistency
c) Battery
d) Accuracy
e) Geometrie
f) Efficiency
g) Energy Resolution

Answer 5

a) Linearity
b) Consistency
c) Battery
d) Accuracy
e) Geometrie

Question 6

What types of QC is usually done for Dose calibrators?
a) Consistency
b) Accuracy
c) Linearity
d) Geometrie
e) All of he above

Answer 6

e) All of he above

Question 7

What types of QC are usually done for Survey meters?
a) Energy Peak
b) Background
c) Calibration
d) Energy Resolution
e) Efficiency
f) Consistency

Answer 7

a) Energy Peak
b) Background
c) Calibration
d) Energy Resolution
e) Efficiency

Question 8

What types of QC are usually done for Uptake probes?
a) Linearity
b) Battery
c) Background
d) Consistency

Answer 8

b) Battery
c) Background
d) Consistency

Question 9

The measurement on gamma camera is collected in which mode?
a) Pulse mode
b) Current mode

Answer 9

a) Pulse mode

Question 10

Which measurement on an ionization meter and dose calibrator are collected in which mode?
a) Pulse mode
b) Current mode

Answer 10

b) Current mode

Question 11

What is the smallest quantity a dose calibrator can accurately measure within +/= 5%?
a) 1mCi
b) 10uCi
c) 20uCi
d) 1uCi

Answer 11

c) 20uCi

Question 12

What is the one reason the GM counter reading decrease as the distance decreases?
a) Dead time
b) Contamination of meter
c) Radiation has decayed away
d) Dead battery

Answer 12

a) Dead time

Question 13

What is the probable cause for a low constancy reading on a dose calibrator?
a) Dead battery
b) Dead time
c) System zeroed with contamination present.
d) Source contaminated

Answer 13

c) System zeroed with contamination present.

Question 14

The event in which each electron produces many ionizations and excites more gas particles, which in turn causes even more free electrons, is called what?
a) Geiger avalanche
b) Continous discharge
c) Townsend avalanche
d) Waterfall effect

Answer 14

c) Townsend avalanche

Question 15

Which of these is NOT an example of a gas-filled detector?
a) Dose calibrator
b) Gamma camera
c) Ionization meter
d) Geiger counter

Answer 15

b) Gamma camera

Question 16

Which of these is NOT an example of a scintillation detector?
a) Thyroid probe
b) Well counter
c) Dose calibrator
d) PET scanner

Answer 16

c) Dose calibrator

Question 17

How is a scintillation detector better than a gas-filled detector?
a) Able to determine the energy of the gamma-ray
b) Can differentiate between different radionuclides
c) Can differentiate between unscattered and scattered gamma rays
d) All of the above

Answer 17

d) All of the above

Question 18

What is the most common inorganic scintillator used in nuclear medicine?
a) NaI
b) BGO
c) Xe
d) NaCl

Answer 18

a) NaI

Question 19

In which region does the dose calibrator operate?
a) Proportion region
b) Geiger-muller region
c) Ionization region
d) Continous discharge region

Answer 19

c) Ionization region

Question 20

The higher the energy of the gamma-ray the more scintillation photons produced in a highly efficient scintillator.?
a) True
b) False

Answer 20

a) True

Question 21

Which part of the detector converts the scintillation photons into an electrical signal?
a) NaI crystal
b) PMT tube
c) Preamplifier
d) Pulse height analyzer

Answer 21

b) PMT tube

Question 22

What is energy resolution?
a) Ability to separate objects close in space
b) Ability to distinguish gamma rays close in energy
c) Ability to determine the exact energy of a gamma ray
d) Ability to see lines and spaces with the bar phantom

Answer 22

b) Ability to distinguish gamma rays close in energy

Question 22

Well, counters and probe detectors usually come as a set. Why do you get different measurements of the same source?
a) Differences in geometry
b) One is a gas detector
c) Different calibration sources
d) Different crystal types

Answer 22

a) Differences in geometry

Question 23

Which of the following collimators will magify an image?
a) Flat field
b) Diverging
c) Converging
d) High resolution

Answer 23

c) Converging

Question 24

Which of the following must be performed every 6 months at a minimum? a) COR b) Sealed source leak test c) Linearity of the dose calibrator d) Area survey of hot lab

Answer 24

b) Sealed source leak test

Question 25

The accuracy of a dose calibrator must be checked upon installation and then: a) Monthly b) Quarterly c) Semiannually d) Annually

Answer 25

d) Annually

Question 26

What happens to image resolution as the distance between a patient and a parallel-hole collimator decreases? a) Improves b) Worsens c) Does not change

Answer 26

a) Improves

Question 27

What happens to the image size as the distance between a patient and a parallel-hole collimator decreases? a) Increases b) Decreases c) Does not change

Answer 27

c) Does not change

Question 28

What part of an imaging system emits light when it has absorbed a photon? a) Photomultiplier Tube b) Pulse height analyzer c) Scintillation crystal d) Collimator

Answer 28

c) Scintillation crystal

Question 29

If two photons strike a sodium iodine crystal at the same time, what will occur? a) Neither event will trigger production of light b) The system will perceive only one event which will contain the summed energy of both photons c) Both events will be correctly perceived d) Only the photon closer to the center of the crystal will be perceived.

Answer 29

b) The system will perceive only one event which will contain the summed energy of both photons

Question 30

The purpose of the pulse height analyzer is: a) To minimize the amount of scattered radiation in the final image b) To convert light into an electrical signal and to magnify that signal c) To convert radioactivity into light d) Th filter out photons which strike the crystal from oblique angles

Answer 30

a) To minimize the amount of scattered radiation in the final image

Question 31

Which of the following can be measured in millimeters? a) Energy resolution b) Spatial resolution c) Field uniformity d) Temporal resolution

Answer 31

b) Spatial resolution

Question 32

An orthogonal-hole phantom cannot be used to test spatial linearity since it does not contain lead bars.? a) True b) False

Answer 32

b) False

Question 33

According to the curve for Cs-137 show in fig 1, what is the percent energy resolution of the system? a) 6.9% b) 8.2% c) 10.5% d) 11.8%

Answer 33

d) 11.8%

Question 34

When using a 150uCi source of Tc99m to check uniformity, a tech measures the count in 1 minute as 53,125. If the background in the room is 405cpm, what is the sensitivity of the system? a) 351cpm/uCi b) 354cpm/uCi c) 356cpm/uCi d) 360cpm/uCi

Answer 34

a) 351cpm/uCi

Question 35

What energies are included if a 20% symmetric window is used for the 364 KeV photopeak of I-131? a) 191-437 b) 328-400 c) 337-391 d) 344-384

Answer 35

b) 328-400

Question 36

Is SPECT imaging, if the image matrix size increased from 64X64 to 128X128, Which one of the following is true? a) Total imaging time may need to be increased. b) Spatial resolution will decrease c) Image reconstruction will be faster d) Image file size will decrease. e) The count rate will decrease.

Answer 36

a) Total imaging time may need to be increased.

Question 37

In PET Imaging, What is the outcome of imaging positrons with a long range of travel before undergoing annihilation? a) Increased rate of random detection b) Increase in streaking artifacts c) Mispositioning where the radioactivity is located d) Improved image resolution

Answer 37

b) Increase in streaking artifacts