ABR Quality Assurance and Quality Control 3

Question 1

AAPM TG-43 provides the formalism for calculating dose rates in:

Accepted Answer

Brachytherapy source dosimetry

Answer

TG-43 established the dosimetry formalism for interstitial brachytherapy sources, using parameters such as dose rate constant, geometry function, radial dose function, and anisotropy function.

Question 2

The Radiological Physics Center (RPC), now known as the Imaging and Radiation Oncology Core (IROC Houston), primarily serves to:

Accepted Answer

Provide independent dosimetric audits for institutions participating in NCI-funded clinical trials

Answer

IROC Houston provides independent remote and on-site dosimetry audits—including TLD and anthropomorphic phantom irradiations—to ensure participating institutions deliver doses accurately for NCI clinical trials.

Question 3

According to TG-142, what is the recommended tolerance for couch vertical, lateral, and longitudinal positioning accuracy?

Accepted Answer

±1 mm

Answer

TG-142 recommends a ±1 mm tolerance for couch positioning accuracy (vertical, lateral, and longitudinal) under monthly QA testing.

Question 4

In brachytherapy QA, the air-kerma strength (SK) of a sealed source is expressed in units of:

Accepted Answer

U (1 U = 1 μGy·m²/h)

Answer

Air-kerma strength is expressed in units of U, where 1 U = 1 μGy·m²·h⁻¹ = 1 cGy·cm²·h⁻¹, and is used as the standard source strength specification in TG-43.

Question 5

Which QA parameter is evaluated during a 'picket fence' test on a linear accelerator?

Accepted Answer

MLC leaf positioning accuracy

Answer

The picket fence test delivers a series of narrow MLC-defined fields at known positions; deviations in the resulting image reveal MLC leaf positioning errors.

ABR - American Board of Radiology Medical Physics Exam Practice Test

ABR - American Board of Radiology Medical Physics Exam Practice Test

ABR Quality Assurance and Quality Control 3