Quiz - Jaszczak & stat analysis

Reference sources for QA must be ….?

NIST Traceable. ± 5% @ confidence level 99%

Activity, source, and reference source for Jaszczak phantom?

14.5 mCi of Tc-99m. Referenced to Co-57 (because similar energy)

What is the minimum shielding requirement for PET/SPECT-CT room?

from floor to 7ft tall. injection room is not shielded

How many holes in typical gamma camera collimator? (size and #)

IDK! look it up

What type of imaging is NM? (PET/SPECT)

parallel image projection. functional imaging

Setup up requirements for J phantom?

Make sure it’s level.

Lid must face into scanner.

Center of phantom must be center of camera.

Subject in center of FOV

How do we do attenuation correction in NM?

CT because it calculates linear attenuation coefficients pixel by pixel. Intrinsic to process of CT

How many half lives required to decay to background levels?

about 10 half lives

What do we do with the phantom after QA is complete?

Decay room for ~10 half lives

How to improve image quality in NM?

Elliptical rotation - more counts, but more challenging

Camera closer to subject - increases count rate, which increases contrast

Maximum activity of patient?

26 mCi

What is the purpose of the collimator? made of what?

Spatial location. Lead alloy, allows it to be made thinner than just lead

How do we determine accuracy of our sources?

Dose calibrator measures activity by measuring current related to ionization of air

→ must be linear

Difference between CT and NM image type?

Both are projection but..

CT — cone type through subject gives magnified projection

NM — is parallel projection gives 1:1 projection

Where is the NM source located during reconstruction?

Practical infinity to account for scatter (NOT inside body)

What is the purpose of defining a “source” for image reconstruction (CT, NM..)?

The source size will determine factor for spatial resolution

Why is background reading allowed to be subtracted from measured radioactive counts?

Both are RANDOM

List 3 uses for Jaszczak phantom

Evaluation of … center-of rotation testing, non-uniformity artifact, attenuation and scatter compensation

acceptance testing