Impact of silicone gel breast prosthesis on post-mastectomy photon beam therapy of a recurrent carcinoma

© 2018 Mashhad University of Medical Sciences. Introduction: Silicone gel breast implants are used for breast reconstruction after mastectomy. In case of cancer recurrence, the radiation oncologists are forced to irradiate through the prosthetic device, which leads to the incidence of dose perturbations during the treatment due to the high atomic number of prosthesis. Regarding this, the present study aimed to investigate the influence of silicone gel thickness on photon beam distribution. Material and Methods: A VARIAN linear accelerator, water phantom (dimensions of 30×30×30 cm3), silicone gel breast prosthesis, and Omni-Pro Accept software were used. Gantry positioned at 0° and a source-to-surface distance of 100 cm, the collimators adjusted to a field size of 10×10 cm2 and photon beam energy of 6 MeV was used. The results obtained with a MCNP Code were validated with the measured data. The beam profiles and PDD curves were also measured for silicone gel thicknesses of 4, 6, 8, 10, 12, 14, and 16 cm with the width of 16.5 cm aligned 1 cm below the water surface. Results: According to the results, the measured and calculated percentage depth dose ratio was ≤ 0.03. Furthermore, the measured and calculated beam profiles were 0.5% and 0.9%, respectively. For the silicone gel prosthesis, the depth dose values at 0.5 cm below the prosthesis were ≤ 2.8%. Conclusion: As the findings indicated, dose perturbations below the breast prosthesis were insignificant. Therefore, breast prosthesis could be concluded to be safe in case of carcinoma recurrence.