(Wednesday, 7/17/2019) 10:30 AM - 11:00 AM
Room: Exhibit Hall | Forum 4
Purpose: To report institutional results from commissioning of the Advanced Collapsed Cone engine (ACE) algorithm using the test cases proposed by the AAPM Working Group on Dose Calculation Algorithms in Brachytherapy (WG-DCAB).
Methods: Two levels of commissioning were carried out as proposed by AAPM TG 186 for Oncentra (v4.5.3). Level 1 and 2 were ACE vs TG 43 and ACE vs Monte Carlo (MC) respectively. Test cases 1-4 were downloaded (http://irochouston.mdanderson.org/RPC/pagerequest.htm?page=BrachySeeds/Model_calculations.html) and imported to the TPS. Testing was performed using the WG generic source with the Flexitron after-loader and the workflow for dose calculation and reporting outlined in the user guide provided for ACE testing (v26 April 2016). For each test case, pre-defined dose–points, dose-maps, dose-profiles, and dose-difference maps at specified planes were evaluated.
Results: Mean (SD) percentage variation of doses at specified points (n=12) for test cases 1-3 for level 1 vs level 2 were 1.1(2.8) vs 0.03(1.6), 0.4(3.2) vs -0.8(1.2) and -0.8(4.2) vs -2.2(1.1) respectively. Mean (SD) percentage variation of dose at specified dose points for test case 4 for level 1 vs level 2 were -321 (791) vs 7.1(33). The high percentage dose variation was attributed to the shielded applicator in test case-4. Subgroup analysis of dose-points in test case-4, in shielding (n=8) vs non-shielding (n=4) regions, resulted in mean percentage (SD) variation of -483(944) vs 4.5(15) and 9.6(44) vs 2(5) for level 1 and 2 respectively. Dose-maps, dose-profiles and dose-difference maps were found to be in accordance with the literature and as explained by the optimization settings of the dose calculation algorithm.
Conclusion: Commissioning of the ACE algorithm using test cases proposed by AAPM WG-DCAB has been carried out. These test cases along with MC reference data have proved to be a useful tool during commissioning and improved the confidence of the hospital physicist.
Keywords
Brachytherapy, Commissioning, Dosimetry
Taxonomy
TH- Brachytherapy: Calibration & Quality Assurance
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