Dosimetric Evaluation of Rice Husk (Oryza sativa) and Agar (Gracilaria spp.) Mixtures as an Alternative Bolus Material in External Electron Beam Radiation Therapy

Abstract

This study investigates the dosimetric performance of rice husk (Oryza sativa) and agar (Gracilaria spp.) mixtures as a potential alternative bolus material in external electron beam radiation therapy. Motivated by the high cost and limited accessibility of commercial boluses in resource-constrained settings, the research employed a quantitative experimental design to evaluate three formulated samples with varying ratios. Dosimetric properties, including surface dose, absorbed dose, and percentage depth dose (PDD), were measured under controlled irradiation conditions and compared with those of a commercial bolus. Results showed that although statistically significant differences existed in surface and absorbed doses, all samples demonstrated identical PDD values, indicating stable depth-dose behavior. Among the formulations, Sample 3 exhibited the closest dosimetric equivalence to the commercial bolus, suggesting its suitability for clinical application. The findings support key theoretical frameworks, including tissue-equivalence, material interaction, and radiation interaction theories. Overall, the study highlights the potential of rice husk–agar bolus as a cost-effective, sustainable, and locally available alternative for improving access to radiation therapy, particularly in underserved regions.