Eavaluation of cumulative bolus performance during external beam radition therapy of patients with scc : treatment panning and film dosimetry

During SCC of the lips, the accumulated bolus is used to overcome the problem of low dose to the lips. The purpose of this study is to evaluate the performance of bolus in increasing the surface dose through the treatment planning system and film dosimetry. Two patients with squamous cell carcinoma (SCC) were included in the present study. Squamous cell carcinoma of the lip is a common malignancy in the head and neck region and one of the most treatable because it usually appears in the early stages. According to the tests performed and the results obtained, it can be concluded that there is a significant difference between the results in the presence of bolus and in the absence of bolus. In the present study, Gafchromic EBT۲ films (ISP, USA) were used for in vivo dosimetry. In the presence of bolus, no significant difference was observed between the measured dose values and the calculated treatment planning system (TPS).For the first patient, the film dose was ۱۹.۲ Gy and the program dose was ۱۱.۲ Gy in each session, which means a difference of ۳.۹%. For the second patient, the film dose was ۲.۲۳ Gy and the program dose was ۲.۱۶ Gy in each session, which means a difference of ۴۸.۳%. The result of the evaluation shows that the film had a higher dose in both patients.

Keywords:

SCC lip cancer , Buildup bolus , Film dosimetry , Treatment planning