NM Instrumentation & Quality Control

How often should COR be obtained?

• At least weekly

• Before each patient

• Every 6 months

• At least monthly

Answer explanation

COR stands for center of rotation. This should be checked at least weekly and preferably each day that tomography will be performed to ensure that the axis of rotation is in the center of the computer matrix for all projections and should be determined for each collimator used. While the computer can correct for misalignments, if the COR needs frequent adjustment, service may be needed.

COR stands for

• Circle of rotation

• Center of rotation

• Correction of rotation

• Center of region

Which of the following collimators will magnify an image?

• Flat field

• Diverging

• Converging

• HD Resolution

Answer explanation

Covering will magnify where as diverging will minify an image.

Which of the following must be performed every 6 months at minimum?

• COR

• Sealed source leak test

• Linearity of the dose calibrator

• Area survey of the hot lab

Answer explanation

Sealed sources must b leak checked every 6 months. Leak checks are made by wipe tests of the sealed sources.

Constancy of the dose calibrator is must be tested:

• Daily

• Quarterly

• Weekly

• Every 6 months

Answer explanation

Constancy is the ability of the dose calibrator to reproduce measurements of source over time. and. should be checked daily. The NRC requires that records be kept for 3 years.

Which piece of equipment would be most useful for detecting low levels of activity?

• Ionization chamber

• Dose calibrator

• Pulse height analyzer

• Geiger Mueller survey meter

Answer explanation

Ionization chamber Is used for high levels of radiation

The dose calibrator is a well type ionization chamber

A pulse height analyzer is an instrument that accepts electronic pulses of varying heights from particle and event detectors, digitizes the pulse heights, and saves the number of pulses of each height in registers or channels, thus recording a pulse-height spectrum or pulse-height distribution used for later pulse-height analysis

Which are ways to obtain an attenuation corrected image on PET and or SPECT/CT?

• Gadolinium¹⁵³ line source

• CT

• Germanium⁶⁸ rod source

• Cobalt⁵⁷ point source

Answer explanation

A Ga⁶⁸ line source or CT may be used for attenuation correction on a PET or SPECT/CT image

Which part of the scintillation camera converts a light pulse into an electrical signal of measurable magnitude?

• Thallium activated sodium iodide crystal

• Pulse height analyzer

• Photomultiplier Tube (PMT)

• Lanthanum bromide crystal

Answer explanation

A crystal produces light. A PMT will convert that light into a electrical signal. The pulse height analyzer will discard unwanted signals from background or interfering isotopes so that only leaks from the isotope being imaged is recorded.

What does SPECT stand for

Which are types of scintillation crystals used in a PET camera?

• Bismuth germanium oxide (BGO)

• Sodium Iodide (NaI)

• Lutetium oxyorthosilicate (LSO)

• Tungsten activated lithium oxide (WLO)

Answer explanation

Tungsten activated lithium oxide (WLO) is made up up. However the symbol for Tungsten is actually W because of the elements other name (wolfram)