NMTCB PET COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)

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NMTCB PET COMPLETE QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS)
QUESTION: The exposure rate of an activity of 1 millicurie (mCi)

measured at 1 centimeter (cm) is called


Ans: - The exposure rate constant (ERC)

For positron emitters, the exposure rate constant (ERC) is about 6 R/h per
millicurie at 1 cm. The exposure rate of a 10 mCi dose of F-18 is approximately six
times greater than that of a 10 mCi dose of Tc-99 m at a distance of approxi-
mately 8 inches.



QUESTION: Quantitative bias that refers to the underestimation of

counts density which differs from what they should be is called:


Ans: Partial-volume effect

PVE is caused by the finite spatial resolution of the imaging system which reveals
how far the signal "spills out" around its actual location. The signal spreading
falsely increases the object size and volume. Image sampling, where voxels in ROI
include the signal from underlying tissues, also contributes to the phenomenon
known as partial-volume effect.



QUESTION: Truncation artifacts in PET/CT imaging are produced by


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Ans: Difference in size of FOV between PET and the CT

Discrepancy between fields of view (FOVs) in a PET/CT scanner—70 cm causes a
truncation artifact when imaging extends beyond the CT FOV-50 cm; as a result no
attenuation correction values for the truncated anatomy are being applied.



QUESTION: Dental fillings, hip prosthetics, or chemotherapy port are

examples of PET/CT imaging artifacts described as:


Ans: Metallic implants artifacts

Metallic implants create streaking artifacts on CT images because of their high
photon absorption. Higher Hounsfield numbers consequently produce high PET
attenuation coefficients and an overestimation of PET findings.



QUESTION: The Property of PET detectors that allows them faster

timing signals for coincidence detection and to work at high count

rates is called:


Ans: The decay constant

The decay constant decides how long the scintillation flashes in the crystal; a
short decay time reduces detector dead time and as a result higher annihilation
rates can be accepted.




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QUESTION: The picturing, description, and measurement of

biological processes at the particle and cellular level is known as


Ans: Molecular imaging

Radionuclide originated molecular imaging techniques such as positron emission
tomography

(PET) and single-photon emission computed tomography (SPECT) capture
functional or phenotypic changes associated with pathology and unfold the
molecular abnormalities responsible to form basis of many diseases.



QUESTION: A PET system capacity to distinguish between two points

after image reconstruction is called:


Ans: Resolution

A PET system resolution, according to NEMA guidelines, is assessed by imaging a
point source in the air and reconstructing the images with no smoothing or
transformation of images. The resolution of the system is affected by the
annihilation ambiguities, the detector ring diameter and the size of the
scintillation crystal.



QUESTION: Allergic reaction that begins within seconds/minutes of

contrast media administration and rapidly progresses to cause




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airway constriction, skin and intestinal irritation, and altered heart

rhythms is called:


Ans: Anaphylaxis



QUESTION: The first PET radiopharmaceutical to receive the U.S.

Food and Drug Administration approval in 1989 was:


Ans: Rb-82



QUESTION: The dose calibrator quality control procedure performed

to assess the device's ability to measure accurately a range of a low

to high activities is called:


Ans: Linearity



QUESTION: The following positron-emitting radionuclides are

isotopes of natural elements present in most biochemical processes

EXCEPT:

(A) O-15

(B) F-18

(C) C-11

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