Kelleter, Laurent;
(2021)
A Scintillator-Based Range Telescope for Particle Beam Radiotherapy.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Particle beam therapy (PBT) is a form of radiation therapy that is used for cancer treatment. Recently, interest in scintillator-based detectors for the measurement of depth-dose curves of therapeutic particle beams has been growing. In this work, a novel range telescope based on plastic scintillator and read out by a large-scale CMOS image sensor is presented. The detector is made of a stack of 49 plastic scintillator sheets with a thickness of 2–3mm and a transverse area of 100 times 100mm2. A novel Bragg curve model that incorporates scintillator quenching effects was developed for the beam range reconstruction from depth-light curves with low depthresolution. Measurements to characterise the performance of the detector were carried out at three different PBT centres across Europe. The maximum difference between the measured proton range and the reference range was found to be 0.46 mm. An evaluation of the radiation hardness proved that the range reconstruction algorithm is robust following the deposition of 6,300 Gy peak dose into the detector. Variations in the beam spot size, the transverse beam position and the beam intensity were shown to have a negligible effect on the range reconstruction accuracy. Range measurements of helium, carbon and oxygen ion beams were also performed. A novel technique for online range verification based on a mixed helium/ carbon ion beam and the range telescope was investigated. The helium beam range modulation by a narrow air gap of 1mm thickness in a plastic phantom that affected less than a quarter of the beam particles was detected, demonstrating the outstanding sensitivity of the mixed-beam technique. Using two anthropomorphic pelvis phantoms it was shown that small rotations of the phantom as well as simulated bowel gas movements cause detectable range changes. The future prospects and limitations of the helium-carbon mixing as well as its technical feasibility are discussed.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | A Scintillator-Based Range Telescope for Particle Beam Radiotherapy |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| Keywords: | Scintillator, Proton therapy, Particle therapy, Range telescope, Quality assurance, Mixed beam, Theranostics, Bragg curve, Depth-Light curve |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10119396 |
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