Characterization of alternative materials for bolus fabrication in radiotherapy

In certain radiotherapy protocols, a more superficial dose distribution is required, necessitating the use of a bolus to ensure adequate dose delivery to the skin and subcutaneous tissues. Although commercially available bolus materials are widely recognized and employed for this purpose, their availability remains limited in many radiotherapy centers across Brazil. This study aimed to evaluate the percentage depth dose (PDD) curve, skin entrance dose, depth of maximum dose, and dose profile to determine the suitability of alternative bolus materials fabricated from gauze and disposable cloth. Dosimetric data were acquired using a 6 MV beam from a linear accelerator, a treatment planning system (TPS), computed tomography (CT), radiochromic film, and an ionization chamber. When compared to the commercial bolus, the disposable cloth bolus demonstrated superior performance relative to gauze, achieving a greater superficial dose increase (0.54 cm vs. 0.24 cm). Both alternative materials increased the skin entrance dose in comparison to treatments without a bolus. However, when benchmarked against the commercial bolus, they exhibited lower efficiency, with reductions of 44% and 29% observed for gauze and disposable cloth, respectively. While alternative bolus materials enhanced surface dose delivery, the reduction in depth of maximum dose remained inferior to that provided by the commercial bolus. In terms of dose profile homogeneity, the disposable cloth bolus outperformed gauze, likely due to its tighter and more uniform weave structure. These findings suggest that the disposable cloth bolus presents a promising alternative for routine clinical application, particularly in settings where standard commercial bolus materials are unavailable. • Low-cost gauze and disposable cloth materials were evaluated for use as bolus in radiotherapy. • These alternative bolus materials increased skin entrance dose compared to no bolus. • Disposable cloth bolus showed better superficial dose enhancement than gauze. • Commercial bolus remained more effective in reducing the depth of maximum dose. • Disposable cloth bolus showed improved dose profile homogeneity over gauze.