NMTCB Instrument Operations & Quality Control 3

Question 1

A dose calibrator linearity test uses a vial of Tc-99m measured repeatedly over several days. What does this test confirm?

Accepted Answer

That the instrument measures accurately across a range of activity levels

Answer

The linearity test confirms that the dose calibrator reads accurately from high activity (millicuries/GBq) down to low activity levels as the source decays.

Question 2

What is the purpose of a constancy test performed on a dose calibrator?

Accepted Answer

To verify day-to-day reproducibility using a long-lived sealed reference source

Answer

Constancy testing uses a sealed long-lived source (e.g., Cs-137 or Co-57) measured daily to confirm the dose calibrator's reproducibility over time.

Question 3

Which parameter defines the minimum separation between two point sources that a gamma camera can still resolve as distinct?

Accepted Answer

Spatial resolution

Answer

Spatial resolution is the ability to distinguish two closely spaced radioactive sources as separate, typically measured in mm FWHM.

Question 4

In PET/CT, a technologist performs a well-counter cross-calibration. What is the purpose of this procedure?

Accepted Answer

To ensure that PET scanner activity measurements agree with those of the dose calibrator

Answer

Cross-calibration ensures that the PET scanner's measured activity concentrations are consistent with dose calibrator readings, enabling accurate quantification.

Question 5

What is dead time in a radiation detector?

Accepted Answer

The period after detecting one event during which the detector cannot register another event

Answer

Dead time is the brief interval after a detected event during which the system is unable to process additional incoming events, causing count loss at high count rates.

(NMTCB) Nuclear Medicine Technology Certification Board Practice Test

(NMTCB) Nuclear Medicine Technology Certification Board Practice Test

NMTCB Instrument Operations & Quality Control 3