The Design of an Audit Test for 60Co Brachytherapy Treatment Planning System

Auditing the treatment planning system (TPS) software for a radiotherapy unit is of paramount importance in any radiation therapy department. A Plexiglas phantom was proposed to measure the ionization of 60Co high dose rate (HDR) source and compare dose points in the planning system for auditing and verifying TPS.

Auditing was performed using a Plexiglas phantom in an end‑to‑end test, and relative dose points were detected by a farmer‑type ionization chamber and compared with the relative dose of similar points in TPS. The audit results were determined as pass optimal level (<3.3%), pass action level (between 3.3% and 5%), and out of tolerance (>5%).

The comparison of the collected data revealed that 80% of the measured values were ≤5% in the pass level, and 20% of the points were out of tolerance (between 5% and 6.99%).

This study documented the appropriateness of the dosimetry audit test and this phantom design for the HDR brachytherapy TPS.