SU-FF-T-257: The Study of the Dosimetric Properties of ‘RadGel’, a New Dosimeter for Three-Dimensional Gel Dosimetry

Abstract

Purpose: The development of advanced radiation treatment techniques such as IMRT has prompted an immediate need for a dosimetrysystem that can provide accurate and convenient measurement of complex three‐dimensional (3D) dose distributions. Geldosimetry has proved a promising candidate, but present gel‐dosimeters are still not in widespread routine clinical use. In this work we investigate the dosimetricproperties of a new 3D dosimetrymaterial, RadGel™, which has potential for application in radiation therapy.Method and Materials: Samples of RadGel TM contained in optical cuvettes (1cm×1cm×5cm) were irradiated in a series of experiments to determine sensitivity to dose,dose rate, energy, and stability of response with time post‐irradiation. Pre and post irradiation measurements were made of the optical‐density profile along the long axis of the cuvettes using a custom laser scanning system at 632nm. The radiation induced spectral optical density (OD) change of RadGel™ was also measured by a conventional spectrophotometer. Results: The spectrophotometric measurements indicated that peak radiation induced OD change occurred at ∼600nm (FWHM ∼100nm). A linear relationship was observed between OD changes and dose, and negligible dependence on dose rate. OD measurements a week after irradiation revealed significant degradation of optical response compared with scans 24 h post irradiation, but the timescale of these changes is still much improved from existing non‐scattering 3D dosimetrymaterials.Conclusion: The RadGel™ material has several attractive qualities for 3D dosimetry. In particular RadGel™ is more robust than established non light‐scattering 3D dosimeters to exposure to air and water. Together with an improved stability of response with time RadGel™ appears a practical and convenient material. Further tests are required on larger volumes of RadGel™ to determine true potential.