Characterization of the Exradin W1 scintillator for use in radiotherapy

• Published in: Medical physics (Lancaster) Vol. 42; no. 1; p. 297
• Main Authors: Carrasco, P, Jornet, N, Jordi, O, Lizondo, M, Latorre-Musoll, A, Eudaldo, T, Ruiz, A, Ribas, M
• Format: Journal Article
• Language: English
• Published: United States 01.01.2015
• Subjects: Calibration; Electrons - therapeutic use; Photons - therapeutic use; Radiotherapy - instrumentation; Temperature; Uncertainty
• ISSN: 2473-4209
• DOI: 10.1118/1.4903757

To evaluate the main characteristics of the Exradin W1 scintillator as a dosimeter and to estimate measurement uncertainties when used in radiotherapy. We studied the calibration procedure, energy and modality dependence, short-term repeatability, dose-response linearity, angular dependence, temperature dependence, time to reach thermal equilibrium, dose-rate dependence, water-equivalent depth of the effective measurement point, and long-term stability. An uncertainty budget was derived for relative and absolute dose measurements in photon and electron beams. Exradin W1 showed a temperature dependence of -0.225% °C(-1). The loss of sensitivity with accumulated dose decreased with use. The sensitivity of Exradin W1 was energy independent for high-energy photon and electron beams. All remaining dependencies of Exradin W1 were around or below 0.5%, leading to an uncertainty budget of about 1%. When a dual channel electrometer with automatic trigger was not used, timing effects became significant, increasing uncertainties by one order of magnitude. The Exradin W1 response is energy independent for high energy x-rays and electron beams, and only one calibration coefficient is needed. A temperature correction factor should be applied to keep uncertainties around 2% for absolute dose measurements and around 1% for relative measurements in high-energy photon and electron beams. The Exradin W1 scintillator is an excellent alternative to detectors such as diodes for relative dose measurements.