Comparison of Dose Distribution Effects for Various Bolus Materials in Electron Conformal Radiotherapy

In this study, the effects of various bolus materials on dose distributions were compared in electron conformal radiotherapy (ECRT). Superflab, Super Stuff pink wax and Paraffin wax bolus materials are used with 15MeV electron energy for dosimetric comparison. Additionally, 10 mm thick Super Stuff pink wax bolus and paraffin wax bolus materials were placed on the right eyelid of a patient. Using electron dose calculation algorithm and ion chamber measurements, dosimetric comparisons were made in the Eclipse treatment planning system (TPS). Both for measured and calculated dose, values were acquired 3 times and averaged for each case. Resulting differences are expressed as percentage differences. Dose differences were obtained in measurements with and without using bolus at several locations of the solid phantom, performed by the Roos Ion chamber. Dosimetric differences of 7-7.5% for Superflab, 10-10.5% for paraffin bolus and 13-14% for Super Stuff pink wax bolus are obtained. Besides, when dosimetric comparisons are made in the treatment planning system for cases with and without bolus; Dose differences were calculated to be 2-2.5% for superflab silicon bolus, 3-3.5% for paraffin wax bolus and 5-6% for Super Stuff pink wax bolus. To increase skin dose in curved anatomical structures in radiotherapy, it is safe to use the paraffin wax bolus material in radiotherapy clinic, as an alternative to Superflab silicon bolus and Super Stuff pink wax bolus materials, due to its low cost and ease of conforming to body surface contours.