Room: AAPM ePoster Library
Purpose: develop Monte Carlo based dosimetry methods to reconstruct organ doses of Wilms tumor patients receiving Co-60 external beam radiation therapy (EBRT) in the context of epidemiologic study of secondary cancer risk.
Methods: Co-60 machine (Theratron, Nordion) consisting of a Co-60 source and collimation system was modeled using XVMC (X-Ray Voxel Monte Carlo) code. Percent depth dose (PDD) and off-axis profiles were calculated for in-field and out-of-field regions in a water tank. These profile calculations were compared to measured values from publication. A pediatric male hybrid computational phantom was employed to simulate a male patient. Beam plans were created in the Pinnacle Treatment Planning System (TPS), and the XVMC simulations were setup using data extracted from the DICOM-RT Plan files exported from the TPS. The organ doses from TPS calculation were compared with those from MC calculation.
Results: PDD and off-axis profiles showed good agreement with measurement in all cases (differences <3%). For the simulated patient, the right kidney was within the treatment field and had a MC calculated mean doses of 30.22 Gy, only .11 Gy below the TPS calculation. The left kidney, heart, and testes were out-of-field with MC calculated mean doses of 3.16 Gy, 0.71 Gy, and 0.11 Gy differing from TPS calculations by 0.11 Gy, 0.71 Gy and 0.01 Gy respectively.
Conclusion: study shows XVMC to be a viable method of dose reconstruction for patients receiving radiation therapy.
This research was supported by the intramural research program of the NIH/NCI, Division of Cancer Epidemiology and Genetics and RO1CA219013.
Funding Support, Disclosures, and Conflict of Interest: This research was supported by the intramural research program of the NIH/NCI, Division of Cancer Epidemiology and Genetics and the National Cancer Institute over the NIH under award number RO1CA219013.
TH- External Beam- Photons: out of field dosimetry/risk analysis