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Persistent URL http://purl.org/net/epubs/work/62113635
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Record Id 62113635
Title Development of an Acoustic Dose-Profile Measurement Technique for Short Pulse Proton and Ion Beams
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Abstract Cancer is the second leading cause of death globally, with radiotherapy treating about 50% of cancer patients. Conventional radiotherapy uses photons (x-rays), however there are several drawbacks, particularly the radiation of healthy cells surrounding the cancerous region. New cancer treatment facilities are using protons and light ions because of their ability to deposit a maximum dose within a small volume of tissue at the end of their range. This thesis introduces LhARA, the Laser-hybrid Accelerator for Radiobiological Ap- plications. LhARA aims to advance radiobiological research by exploring the therapeutic benefits and biological responses of di!erent particle beam characteristics. Using pulsed proton and light-ion beams, LhARA will deliver a variety of di!erent ions, beam widths, pulse durations and repetition rates, flexibly and precisely. To minimize uncertainties, real-time dose delivery monitoring is essential. This work presents the SmartPhantom, a novel detector for monitoring the three-dimensional dose ac- cumulation when using nanosecond-scale pulsed ion beams. The proposed instrumentation introduces novel capabilities, such as providing calibrated feedback, unlike other monitoring devices that provide a relative, not an absolute, determination of the delivered dose. The proposed detector leverages ultrasound waves induced by the transient pressure increase as the beam propagates through matter. Due to the high speed of ultrasound waves, feedback can be provided in fractions of a second. Ultrasound waves are typically detected by transducers, however, they only provide a relative dose determination. To calibrate the acoustic response, a liquid scintillator serves as the propagating medium, forming the inner volume of SmartPhantom. The detection of the scintillation light emitted during the ion beam propagation, combined with the known photon yield, enables the absolute – vii – three-dimensional deposited dose to be determined. An initial evaluation of the optical system and liquid scintillator properties was con- ducted at the MC40 cyclotron in Birmingham, followed by a final evaluation of the hybrid system at the Laser-driven Ion (LION) accelerator at the Center for Advanced Laser Ap- plications (CALA) in Munich, Germany. The detector’s design was optimized through a simulation pipeline that integrated laser-driven source parametrization in Python, acceler- ator beamline modeling and particle tracking with BDSIM, energy deposition calculations using Geant4, and acoustic wave generation, propagation, and detection in Matlab. The results revealed a strong correlation between optical and acoustic measurements, demonstrating the detector’s potential to provide an accurate, real-time calibrated dose deposition distribution. This validation lays the foundation for developing a system that can be used in a clinical setting.
Organisation PPD , STFC , LhARA
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Language English (EN)
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Thesis PhD, Imperial College London, 2025. 2025