engleski

Dose measurements with Radiophotoluminescent glass dosimeters in therapeutic proton beams

In recent years, radiophotoluminescent glass dosimeters have been increasingly used, especially for measuring doses in therapeutic proton beams. Reported data on measurements and characterization of RPL detectors are mainly related to photon and electron beams, while data for proton beams are limited and not always consistent. The increasing role of proton radiotherapy in cancer treatment requires detailed characterization and adaptation of dosimetry methods to charged particle measurements. In particular, the use of passive detectors in the charged particle field is challenging due to their energy and LET dependence and dose response. Moreover, the lack of mailed dosimetry audits in proton therapy centers in Europe foster detail characterization of the response of different passive detectors in various proton fields (beam modulation, range, etc.). In the framework of EURADOS WG9, the Ruđer Bošković Institute has participated in several measurement campaigns in different proton therapy centers with radiophotoluminescent (RPL) glass dosimeters type GD -352M and GD -302M. For the study of response in Spread out Bragg peak (SOPB) the detectors were positioned in a standard 30 cm × 30 cm × 30 cm PTW water phantom. The SOBP proton range (from 5 cm to 25 cm) and modulation width (from 5 cm to 20 cm) were gradually changed to determine the dosimeter response in 9 different SOBP configurations. Dose dependence was measured at the middle of the SOBP for doses ranging from 0.5 Gy to 120 Gy. The long-term fading of RPL detectors irradiated with proton beams was also determined under normal ambient conditions over a period of 1.5 years. To achieve high precision of measurements with RPL detectors in proton beams, it is of great importance to have detailed knowledge of their behaviour at different beam parameters (different ranges and modulations), LET spectra and dose levels. An overview of selected results in proton beams measured with RPL detectors from different measurement campaigns will be presented.

RPL dosimeters ; therapeutic proton beams ; EURADOS WG9

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