Room: Exhibit Hall | Forum 4
Purpose: To develop and clinically implement a quality assurance (QA) software program to perform independent checks of brachytherapy dose calculations.
Methods: A generic brachytherapy QA program with graphic user interface was written in MATLAB. The program uses AAPM-TG43 formulism to calculate the 3D dose distribution from multiple sources/dwell positions, and allows comparison of point doses and dose volume histograms (DVH) calculated by the program to the clinical treatment planning system (TPS). Dose differences along the coronal, sagittal, and axial planes centered on a chosen structure (e.g. PTV) can also be displayed, and a PDF report of the evaluation can be generated automatically.We implemented the program for use with our high-dose-rate (HDR) brachytherapy by entering TG43 data for our Ir-192 source (Flexisource, Elekta/Nucletron) and treatment plans from our clinical Oncentra Brachytherapy TPS (Elekta/Nucletron). The program was initially validated for single and dual dwell positions against both manual and TPS point dose calculations. Further validation was performed through comparisons of point dose and DVH calculations for clinical vaginal vault, cervix and interstitial breast brachytherapy plans.
Results: A comparison of the program-calculated and manual point dose calculations for single dwell positions showed a mean difference of -0.7% (maximum: -3.8% near the source tip). The program and TPS calculations for single and dual dwell positions mean difference was better than 0.2%. Comparisons for point doses in different dose gradients for vaginal vault, cervix and interstitial breast plans showed mean agreements of -0.2%, -0.4% and -0.1%, respectively. A qualitative comparison of DVHs also showed excellent agreement.
Conclusion: The in-house developed QA program provides an efficient and inexpensive tool to perform independent calculation checks of HDR brachytherapy treatment plans. This open-source program is available to other users and may be easily adapted for multiple clinical applications including LDR, other sources and other TPS.
Funding Support, Disclosures, and Conflict of Interest: Z. Whatman was supported by the Harold E. Johns Studentship Program of Cancer Care Ontario
Not Applicable / None Entered.