Scintillating array for real-time high-resolution dosimetry

Guerreiro, Duarte Rafael

http://hdl.handle.net/10400.5/100694

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Authors

Guerreiro, Duarte Rafael

Advisor(s)

Peralta, Luis Filipe dos Santos Garcia

Sampaio, Jorge Miguel de Brito Almeida

Abstract(s)

Scintillators have long been used as particle detectors, with plastic scintillators like Scintillating Plastic Optical Fibres (SPOFs) gaining attention in radiotherapy. These materials offer key advantages: tissue equivalence, fast signal production, and high spatial resolution. Thiswork focuses on developing a dosimeter based on an SPOF array for radiobiology studies and proton therapy quality assurance. For radiobiology, an innovative approach involves attaching cell cultures directly to the SPOF array, potentially reducing measurement errors caused by traditional culture plates. This requirement shaped the dosimeter’s design, which includes an SPOF array housed in a light-tight, stable irradiation box. Simulations demonstrated the detector’scapability to characterize radiation fields, including complex mini-beam configurations, without damaging the photomultiplier used. Optical simulations further confirmed that cross talk between fibres does not compromise radiation profile accuracy. Experimental testingi nvolved X-ray and electron irradiations, showing reproducibility within 3%. Clinical proton irradiations wer eperformed to validate a novel method for reconstructing the Bragg Peak using proton flux measurements and Monte Carlo simulations. Proton energy deposition was calculated at varying depths in a PMMA phantom, specially designed in a step wise format to allow precise thickness adjustments. These tests utilized a 130 MeV proton beam at the Holland Proton Therapy Center and relied on the Hades experiment’s Trigger and Readout Board 3, a Time-to-Digital Converter for event rate measurements correlated with proton flux. The results demonstrated that SPOFs effectively address light yield saturation issues, making them suitable for proton beam machine quality assurance. This method combines simulations and depth measurements to expand the potential of SPOFs in radiotherapy applications.