ABR Quality Assurance and Quality Control 2

Question 1

The gamma (γ) index used in IMRT patient-specific QA combines which two criteria?

Accepted Answer

Dose difference and distance-to-agreement

Answer

The gamma index simultaneously evaluates dose difference (DD) and distance-to-agreement (DTA) to provide a single pass/fail metric for IMRT QA comparisons.

Question 2

AAPM TG-119 was developed primarily to establish:

Accepted Answer

Commissioning benchmarks and test cases for IMRT planning and delivery

Answer

TG-119 provides IMRT commissioning test cases with known dose distributions to help institutions benchmark their IMRT planning and delivery systems.

Question 3

Which AAPM report provides QA guidelines specifically for CT simulators used in radiation therapy?

Accepted Answer

TG-66

Answer

AAPM TG-66 addresses the quality assurance of CT simulators and establishes acceptance testing and periodic QA procedures for these devices.

Question 4

An EPID (Electronic Portal Imaging Device) is most commonly used in linac QA for:

Accepted Answer

Patient position verification and transit dosimetry

Answer

EPIDs are primarily used for patient setup verification via portal imaging and for transit dosimetry to detect delivery errors during or after treatment.

Question 5

What is the recommended passing criteria (gamma pass rate) for patient-specific IMRT QA according to AAPM TG-218?

Accepted Answer

95% of points with γ(3%/3mm) ≤1

Answer

TG-218 recommends a universal tolerance of ≥95% passing rate using 3%/3 mm criteria with a 10% dose threshold for IMRT patient-specific QA.

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 2