Dosimetry verification of chest wall radiotherapy planning using virtual bolus compared to plasticine bolus for 3DCRT and IMRT

Abstract. Aim: Plasticine bolus has been used widely in Indonesia to achieve dose coverage in breast cancer radiotherapy based on treatment planning using virtual bolus. The purpose of this study was to evaluate dosimetry differences between virtual bolus and plasticine bolus on both of 3DCRT and IMRT planning. Methods: Ten original chest CT simulation files were modified as a pair file with virtual bolus and plasticine bolus. 3DCRT and IMRT planning was made for each file using "ECLIPSE" software. We compared the dosimetry result for Conformity Index (CI), Homogeneity Index (HI), and D2%. Findings: We found that for 3DCRT breast cancer planning, HI and CI were lower for plasticine bolus compared to virtual bolus. There is no significant difference for D2% between plasticine and virtual bolus. IMRT breast cancer planning parameters for HI, CI, and D2% were lower for plasticine bolus than a virtual bolus. Conclusions: Virtual bolus causes an overestimation of breast cancer radiation dosimetry. Several considerations are needed for using plasticine bolus to overcome the dosimetry decrement.