Advanced graphite-based dosimetry: A novel approach for HDR 60Co brachytherapy

High-dose-rate (HDR) ⁶⁰Co brachytherapy is widely used for cancer treatment, offering precise radiation delivery to tumors while minimizing exposure to surrounding healthy tissues. However, steep dose gradients and limited real-time dose verification pose significant challenges, making accurate in vivo dosimetry essential for treatment safety and efficacy. This study investigates the potential of graphite-based materials for in vivo dosimetry in HDR ⁶⁰Co brachytherapy, aiming to achieve accurate and reliable radiation dose measurements. Thermoluminescence (TL) and photoluminescence (PL) responses, along with Raman and Fourier-transform infrared (FTIR) spectroscopic features, were analyzed to evaluate the correlation between radiation exposure and structural modifications within a dose range of 0.5 to 10 Gy. Two commercially available graphite-based materials i.e. 50 μm thick graphite sheets (GS) and 0.3 mm diameter 2B-grade polymer pencil lead graphite (PPLG) were examined for their dosimetric suitability. Results indicate that defect states in these materials significantly influence their luminescent properties, with PPLG exhibiting superior TL sensitivity, stability, and linear dose response compared to graphite sheets. Raman and FTIR spectroscopy further confirm radiation-induced structural changes, correlating with TL and PL behaviors. These findings suggest the preliminary potential of graphite-based materials, particularly PPLG, for radiation dosimetry using an HDR ⁶⁰Co source. The results indicate that PPLG may serve as a cost-effective and high-precision dosimetric material, with promising applicability in HDR ⁶⁰Co brachytherapy to support improved treatment accuracy and patient safety.