First Comprehensive Implementation of the Upcoming Aapm TG-350 Proton Pbs Protocols: System Validation and Inter-Room Consistency
Abstract
Purpose
The upcoming AAPM Task Group 350 (TG-350) report proposes a standardized end-to-end test suite for commissioning proton pencil-beam scanning (PBS) systems. This work presents the first complete implementation of all eight TG-350 tests to benchmark an IBA Proteus® PLUS system. Beyond standard commissioning, we demonstrated the utility of the TG-350 framework for performing robust multi-room beam-matching quality assurance, a critical step for multi-facility consistency. Feasibility of a Monte Carlo log-file based validation method was also preliminarily assessed as a supplementary tool.
Methods
All tests were planned in RayStation and delivered to a solid-water phantom. Point doses were measured with an IBA CC01 ion chamber, while 2D dose distributions were verified with Gafchromic™ EBT4 film and an IBA Matrixx PT array. Gamma analysis (3%/3mm) and point-dose comparisons followed TG-350 methodology. Beam-matching was assessed by comparing per-field Matrixx results between the reference room and a second, matched room; Complete point-dose, film, and MatrixxPT data acquisition for a third matched room is currently underway. Additionally, log-files were used to reconstruct 3D doses using a secondary calculation platform for validation.
Results
System performance met all TG-350 benchmarks. Point-dose confidence limits were 0.0478 (high-dose) and 0.0483 (low-dose). The mean per-field gamma pass rate was 99.8% (CL 0.810), significantly surpassing the TG-350 benchmark (CL 4.06). Composite film measurements yielded a mean pass rate of 96.6% (CL 9.96). Beam-matching analysis of the initial matched pair showed inter-room gamma passing rate differences below 0.5%, confirming excellent consistency. Preliminary log-file validation yielded an average gamma pass rate of 98.8%.
Conclusion
The PBS system's performance successfully met all TG-350 standards. This work confirms that the upcoming TG-350 is also an effective framework for ensuring beam-matching consistency across multiple treatment rooms. The log-file method shows promise as an efficient validation alternative.