Poster Presentation – Abstracts Archive

UK & Ireland Prostate Brachytherapy Conference 2017

Abstract number 10

Independent verification of brachytherapy planning system calculations using Matlab Code

Esteve S*; Badusha A*; Workman G*
*Belfast City Hospital

AIMS/INTRODUCTION: To investigate the accuracy and performance of an independent dose calculation program (Matlab) in the verifi cation of treatment dosimetry data for both HDR and LDR treatment planning systems.

MATERIALS/METHODS: Fifteen individual treatment plans created using Oncentra Masterplan, OMP v4.1 (n=5), Oncentra Prostate, OCP v4.2.2 (n=5) and Variseed, VS v9 (n=5) were evaluated. The program uses the published source data (Ir-192 and I-125) as the primary input for dose calculation (TG 43) and accounts for 2D anisotropy. DICOM RT fi les from patient plans, exported from the TPS, were directly used as input data in the program. For all plans, dose calculation was performed on random dose points (4 points/ patient) created in both high and low dose gradient regions. The results were compared to the TPS calculation and also a standard excel spreadsheet. Other treatment parameters were also verifi ed including: total reference air kerma, applicator type, standard dwell positions, catheter length and total treatment time.

RESULTS: Independent dose calculations of all dose points using Matlab program were within 1% of the TPS calculated values. The mean error in dose calculation between the Matlab code and TPS were -0.01% ± 0.20% (OMP), -0.10% ± 0.02% (OCP) and -0.02% ± 0.05% (VS). The mean error between the excel program and TPS were 0.62% ± 1.6% (OMP), 1.92% ± 0.6% (OCP) and -0.50% ± 2.26% (VS) respectively. The program was also found to be sensitive to errors created deliberately in dummy cases such as incorrect dose prescription, inconsistent catheter lengths and dwell positions and wrong reference source data.

CONCLUSIONS: The program has been validated with clinical cases created with three TPS and found to be a useful tool in independently verifying the calculation of dose in brachytherapy treatments.