Source of Support: None, Conflict of Interest: None
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For superficial lesions of the skin/soft tissue with depths less than 2 cm, it is conventional to select
superficial x-rays for treatment since it provides a cost effective treatment compared to a low-energy electron beam. For certain lesion sites, the proximity of a bone may result in dose homogeneity. We have investigated the dosimetric differences between a 100 kV, 3.0 mm Al HVLand a 6 MeV electron beam of 5 cm size. A bone thickness of 1 cm with 0.5 cm tissue in the forehead region was considered. Using the ITS Monte Carlo code, the photon and electron central axis depth doses were first simulated and matched to the available machine data and then used to predict dose distribution for the case. Our results demonstrate that the dose to the bone may exceed 300% in the case of the superficial x-ray beam as opposed to a 2% decrease in the case of the electron beam.
