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Validation and End-To-End Testing of a New Proton Treatment Planning System

Z Su

Z Su*, R Slopsema, Z Li, University of Florida, Jacksonville, FL

TU-A-108-3 Tuesday 8:00AM - 9:55AM Room: 108

Purpose: To perform validation of a novel Spread-Out-Bragg-Peak (SOBP) modulation table method and to perform commissioning and end-to-end testing of the Pinnacle proton treatment planning system (TPS) for dose algorithm accuracy and clinical functionality.

Methods: Beam model parameter values were determined using measurements in air and water. The effective-SAD, virtual-SAD, effective-source-size, and Bragg Peaks (BP) were calculated for each nozzle option for double-scattering delivery in an IBA system. We then generated SOBPs for specific modulation values using a subset of BPs which produce a full plateau SOBP. Tables of modulation and BP cumulative weights were used to produce the SOBP functions for each option. Patient treatment plans for brain and prostate sites and corresponding apertures and range compensators were generated. The patient plans were copied onto a water phantom using built-in TPS tools. Central axis depth dose profiles were measured using 1D scanning inside a water tank. Planar doses were obtained using a MatriXX 2D ion-chamber array located at isocenter, and 2 cm upstream and downstream from isocenter. Corresponding planes and profiles were calculated and compared with measurements.

Results: Comparisons between measured SOBPs for various sub-options confirmed the novel beam model approach was clinically acceptable to within 1-3% error at the SOBP entrance region. The measured ranges and modulations were within 1 mm of calculated ones. The agreement between measured and calculated 2D planar dose data is 98% at the three different depths using 3 % and 3 mm gamma criteria.

Conclusion: A novel modulation table method was validated through end-to-end testing of a commissioned Pinnacle proton TPS for an IBA delivery system. This approach covers all sub-options for a given option. Analysis of agreement between calculated and measured profiles indicates that the Pinnacle proton dosimetric accuracy is comparable to our currently used commercial proton TPS.

Funding Support, Disclosures, and Conflict of Interest: Philips Medical Systems

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