Ultra-thin silicon strip detector for protontherapy beam monitoring
(2014)
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- Authors
- Supervisors
- Flandre, Denis
- Abstract
- Radiation therapy plays a major role in cancer treatment. When compared to other ionizing particle such as electrons or X-Rays, protons have the significant advantage of sparing more healthy tissues for the same damaging effect, or dose, on the tumor. Protontherapy is therefore a fast growing application. Countless technological developments in the protontherapy field aim at sharpening the delivered dose gradient between the tumor and the surrounding tissues in order to lessen side effects. Pencil Beam Scanning (PBS), which consists in a thin proton beam scanned over the tumor area, is the most advanced implementation of protontherapy. PBS is very promising in terms of treatment efficiency since it enables very high dose gradients when the beam size is small enough. Either for safety reasons or for treatment precision purposes, beam monitoring with active sensors during the treatment session is of essential need. Nowadays, several types of monitors and detectors are used to measure the beam profile, localization and intensity. However, during the patient irradiation, these bulky detectors are removed from the beamline to prevent them from degrading the beam by increasing the beam size through scattering interactions. To tackle this technological problem, we proposed an ultra-thin silicon strip detector solution to monitor the beam without critically degrading it. The main objective of this work is to study the influence that the Si thickness has on the following most relevant aspects of the novel detector: degradation of the beam, fabrication feasibility, and behavior and detection response. The main objective was reached through a 3-step method. First, quantifying the influence that the detector thickness has on the beam quality. Second, proposing, after various tests in micro-nano-fabrication cleanrooms, a design and a process to fabricate, from scratch, a completely new prototype as thin as 5 microns. Third, characterizing the novel detector through I-V, C-V and resistive measurements as well as the detector responses under a 1060nm laser beam and a 62 MeV proton beam. The third step aims at validating the proposed design and process as well as enabling further improvements. In the light of all the results, this doctoral work is a success for two reasons. First, as shown in the manuscript, the proposed solution performs much better than any existing beam profile monitor (BPM) reported in literature. Second, there exists no comparable ultra-thin silicon based device for protontherapy BPM purposes. Thanks to its originality and good performances, the novel detector is an achievement and thus sets a new standard for all coming beam monitors with negligible degradation of the treatment beam.
- Affiliations
Citations
Bouterfa, M. (2014). Ultra-thin silicon strip detector for protontherapy beam monitoring. https://hdl.handle.net/2078.5/199450