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Background: Plastic scintillators have been used as radiation detectors for the past few years, as they are water-equivalent and independent of the dose, dose rate, and angle of incidence. In addition, they are also independent of the presence of a magnetic field and could be used for in vivo dosimetry in an MR-Linac. With the advent of a new commercial scintillation detector, Blue Physics Model 10,its characterization has been performed on an MR-Linac with a view to future applications. Purpose: To perform the dosimetric characterization and study potential applications of a novel commercial plastic scintillation detector in a MR-Linac. Methods: Scintillation detector description, calibration procedure, short-term repeatability, dose-response linearity, dose-rate dependence, angular dependence, and temperature dependence have been studied. Percent-depth-dose (PDD) and beam profiles were measured for small fields and a standard field, as well as output factors, for comparison with other PTW detectors: a diamond diode and PinPoint and Semiflex 3D ionization chambers. The suitability of the plastic scintillator for in vivo dosimetry in a magnetic field has also been studied measuring the dose to a point in an anthropomorphic phantom while acquiring MR imaging. This measured dose was compared with that calculated with Monaco planning system and with that measured with a PTW Semiflex 3D chamber, the latter without acquiring MR images. Results: Short-term repeatability presented negligible variations (<0.4%) for 100 and 20 MU. Similar results were obtained for dose-response linearity and dose-rate dependence. A small angular dependence was determined, while the scintillator resulted practically independent of the temperature. PDDs showed excellent agreement except in the build-up region, and calculated penumbras with the profiles given by the scintillator were between the ones obtained with the diamond detector and the PinPoint ionization chamber. Measured OF with the scintillator were the highest between all detectors, 1.26% higher than the value obtained with the microdiamond for the smallest field measured, 0.5 × 0.5 cm2. Finally, the total dose to a point measured with the scintillator was 0.51% higher compared to that calculated by the planning system. Conclusion: The Blue Physics model 10 scintillation system showed excellent dosimetric characteristics. Its response independent of the temperature and the presence of a magnetic field make it suitable for in vivo dosimetry in an MR-Linac while acquiring MR images, which could solve the impossibility of performing a dosimetric QA for each adapted plan. Furthermore, its temporal resolution allows independent radiation pulses to be measured and visualized, which could be used in future applications. [ABSTRACT FROM AUTHOR]

Radiation-induced oral mucositis (RIOM) is one of the major oral complications caused by radiotherapy (RT), and can lead a negative impact on patients' quality of life. Considering that there is no specific radiation therapy dose constraint for oral mucosa, the need to study the correlation between absorbed dose and effect in this area is crucial. This pilot study aims to report in vivo OSL dosimetry protocol to investigate the dose distribution in the oral mucosa in patients with oral cancer using Intraoral customised Stent (IOS). For measurements, aluminium oxide nanoDot dosimeters and a microStar ii OSL reader from Landauer Inc. were used. The OSL dosimetry system was calibrated with a 6 MV photon beam using an Elekta Synergy linear accelerator and solid water phantoms following the recommendations of the AAPM TG 191 protocol. The dose distribution in the oral mucosa using seven OSL dosimeters fixed on the intraoral stent was evaluated and compared with the dose distribution available from the RT planning for the patient. Our experimental results showed the expected linearity response of the nanoDot dosimeters from 20 to 200 cGy. The repeatability of readings was better than 1.0% in all commissioning measurements. The uncertainty budget of the commissioning analysis resulted in an overall type An uncertainty of ∼3.4% at the 1-sigma level for dose calculation, compatible with the TG 191 protocol. The dose distribution in the oral mucosa was assessed and dose deviations up to 35% can be found in high dose gradient regions of the treatment planning. This type of deviation may impact on the development and progression of RIOM, as analysed in this protocol. It is feasible to establish this procedure in vivo dosimetry for a patient undergoing RT using a multidisciplinary approach. Additionally, intraoral customised stents can decrease radiation doses in the oral mucosa, and the understanding of the dose distribution in the oral mucosa may help to minimise damages from radiation. • Landauer microStar ii and nanoDot dosimeters applied to in vivo measurements. • Oral mucosa dosimetry protocol establishment. • Monaco™ HD treatment plan compared with experimental measurements. • Dosimetric protocol able to identify hot and cold points of the planned treatment. [ABSTRACT FROM AUTHOR]