MO-D-BRB-02: The Radiological Physics Center's Quality Audit Program: Where Can We Improve?

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• The Radiological Physics Center (RPC) has a 44-year history of Quality Assurance (QA) for NCI-sponsored clinical trials.
• Ensuring accurate dosimetry is critical for effective cancer treatment and patient safety.

Purpose of the Study:

• To analyze the findings from RPC's QA audits of participating institutions.
• To identify common dosimetry discrepancies and evaluate the effectiveness of QA protocols.

Main Methods:

• On-site dosimetry reviews, including machine measurements and personnel interviews.
• Remote audits using mailed dosimeters (OSLD/TLD), data comparisons, and phantom verifications.
• Evaluation of treatment planning algorithms and institutional QA procedures.

Main Results:

• Frequent recommendations concern TG-40 QA tests, wedge factors, and small/off-axis field outputs.
• Ion chamber beam calibrations meeting criteria have returned to pre-TG-51 levels.
• While few beams exceed OSLD/TLD criteria (~3%), discrepancies affect a significant percentage of institutions (12-20%).
• Anthropomorphic phantom passing rates are improving, with prostate phantoms having the highest success rate.

Conclusions:

• RPC's QA program continues to identify and help resolve numerous dosimetry errors.
• The RPC plays a vital role in maintaining high-quality dosimetry standards in NCI-sponsored trials.