SU-E-T-750: Interfacing the Pencil Beam Redefinition Algorithm with a Commercial Treatment Planning System

Abstract

Purpose: The purpose of this work was to interface the pencil beam redefinition algorithm (PBRA) dose engine with the Pinnacle treatment planning system (TPS) for use in bolus electron conformal therapy (ECT) dose planning. Currently Pinnacle TPS uses the Hogstrom pencil beam algorithm (PBA). Methods: A C program that calculates electron dose using the PBRA has been developed. This program inputs the Pinnacle files for the CT data, the user‐generated plan data, and the PBA beam data. The 3D calculated dose outputs a binary file that is uploaded into Pinnacle. This method allows the Pinnacle TPS to be used for plan analysis, e.g. dose display and dose volume histograms of the planning target volume and normal tissues Results: To date our program has been validated by demonstrating, for each beam energy, that agreements of PBRA calculated with measured dose distributions in a water phantom, as a function of field size and SSD, are consistent with previously published results. Also, the accuracy of the PBRA in heterogeneous phantoms agrees with previously published geometric phantom measurements and with patient based phantoms measurements (subject of companion paper). The PBRA is advantageous because it requires no additional beam commissioning data and its accuracy in patients is comparable to Monte Carlo. Calculation times in water for 4×4cm and 20×20cm fields for the 9 MeV beam are 5sec and 120sec respectively on a 2.93Ghz processor using a non‐optimized code. Using the 20 MeV beam these times are 14sec and 290sec, respectively. Conclusion: Our stand alone C program demonstrates a reasonable way to perform patient dose calculations using the PBRA with the Pinnacle TPS. Use of the PBRA might be beneficial for some sites when planning bolus ECT. This work was supported in part by a research agreement with .decimal Inc.