Experimental evaluation of the accuracy of skin dose calculation for a commercial treatment planning system

The present work uses the Eclipse treatment planning system (TPS) to investigate the accuracy of skin dose calculations. Micro-MOSFETs (metal oxide semiconductor field effect transistors) were used to measure skin dose for a range of irradiation conditions (open fields, physical wedges, dynamic wedges, various source-to-surface distances) for 6-MV and 10-MV beams, and the results were compared with the calculated mean dose to a "skin" structure 2 mm thick for semi-cylindrical phantoms (representative of a neck or breast). Agreement between the calculated and measured skin dose values was better than +/- 20% for 95% of all measured points (6-MV and 10-MV X-ray spectra alike). For a fixed geometry, the TPS correctly calculated relative changes in dose, showing that minimization of skin dose in intensity-modulated radiation therapy will be effective in Eclipse.