KEY POINTS
- Investigators evaluated whether locally fabricated phantoms could substitute for a commercial thorax phantom during TPS verification using IAEA TECDOC-1583 methodology.
- Dosimetry was performed with an Elekta Versa HD 6-MV linac and Monaco v6.1.2.0 TPS, comparing a commercial 002LFC IMRT Thorax Phantom with custom acrylic and raw-beeswax heterogeneous phantoms.
- Both locally produced phantoms reproduced the commercial phantom dimensions of approximately 30 × 30 × 20 cm³ and incorporated tissue-, lung- and bone-equivalent components including acrylic or beeswax, cork and PTFE.
- CT calibration used identical 120-kVp, 2.5-mm slice acquisitions. Material uniformity was considered acceptable within ±2%, while agreement of measured versus reference CT numbers used an acceptance threshold of ±20 HU.
- Across the IAEA 3DCRT verification cases, measured and TPS-calculated doses were generally within the ±4% IAEA acceptance tolerance, including measurements through heterogeneous lung- and bone-equivalent regions.
- Both the acrylic and beeswax systems produced dosimetric performance comparable with the commercial thorax phantom, supporting their use for local TPS validation when conventional commercial QA equipment is inaccessible.
- The results apply specifically to the tested 6-MV 3DCRT / Monaco workflow. They do not establish equivalence for highly modulated IMRT, VMAT, stereotactic or other high-gradient applications without additional validation.
CLINICAL TAKEAWAY
For centres where commercial dosimetry phantoms are financially or logistically inaccessible, carefully fabricated local phantoms may provide a viable route to internationally structured TPS QA. The result is especially relevant to LMIC radiotherapy programs, but each locally produced device still requires material characterization and validation within its intended clinical use.