In vivo measurement of radiation dose during brachytherapy treatment using scintillation detectors

Introduction: In vivo verification of the delivered dose in brachytherapy remains an unsolved dosimetric problem. Conventional detectors based on ionization chambers, semiconductors or thermoluminescent (TL) materials based on LiF or Al2O3:C compounds cannot be used for this purpose. The first way to solve this problem is to use dosimetric materials that can be placed in the patient's body to record in-situ the delivered radiation dose using the OSL and/or scintillation phenomena.Material and Methods: In this work, it was proposed to use a known scintillation crystal of Ce3+ doped Ga3Ga3Al2O12:Ce garnet (GAGG:Ce) attached with an long optical fiber to measure in situ the radiation dose during brachytherapy treatment. The measurements were first performed in a phantom, and then on patients in the clinical conditions of the Oncology Center in Bydgoszcz.Results: The obtained results are very encouraging. Luminescence spectra from scintillators were recorded using a long optical fiber and a sensitive spectrometer which can be placed in a safe place. Measurements on the phantom showed the perfect linear correlation between the dose and signal registered by detector based on the GAGG:Ce crystal. Meanwhile, clinical measurements are subject to some uncertainty regarding the accuracy of detector placement in the treatment planning system and possible passive emission response of the optical fiber.Conclusion. Scintillation crystals combined with optical fibers and very sensitive luminescence spectrometers create an ideal measurement system for in situ determining the dose of various ionizing radiations. However, their use in clinical practice requires the development of procedures for precisely positioning the detector in relation to the radiation target.