Room: Davidson Ballroom A
Purpose: Recently, we developed a novel radiochromic dosimeter based on the colorization due to the formation of polyvinyl alcohol-iodide (PVA-I) complex. This dosimeter is colorless before irradiation but develops red after irradiation. In particular, the dosimeter can be initialized by heating after irradiation, resulting repeatedly used. The purpose of this study is to investigate the thermal characteristics and the influence to the reuse in the PVA-I gel dosimeter.
Methods: The PVA-I gel dosimeter prepared in this study consists of PVA, potassium iodide (KI), fructose as a reducing agent, and gellan gum as a gelling agent. It was subdivided into standard spectrometer cuvettes (10 Ã— 10 Ã— 45 mmÂ³). The PVA-I gel dosimeters were irradiated in a water equivalent phantom by 6 MV X-rays at different doses (1-25 Gy). After irradiation, the dosimeters were stored in an incubator to investigate the thermal characteristics (the decolorization rate) at different temperature (20, 35, and 45Â°C). The influence of the reuse in the dose responses was also investigated by repeating initialization and irradiation. Their optical density (OD) was assessed using a flatbed scanner (EPSON ES-10000G).
Results: In the case stored at 20Â°C after irradiation, the linearity of the dose-OD response was maintained with RÂ² above 0.990 for 2 days. In the case stored at 35Â°C and 45Â°C, the OD decayed (decolored) to the background level after 12 hours and 6 hours, respectively. A non-negligible increase of the OD was observed after 8 times reuses by heating at 35Â°C while good reproducibility and linearity with RÂ² above 0.995 were observed by heating at 45Â°C.
Conclusion: Good reproducibility and linearity of the PVA-I gel dosimeter were observed in the repeating initialization by heating at 45Â°C. We propose this reusable radiochromic gel dosimeter for the clinical 3D dose evaluation though further investigation is required.