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Accurate dosimetry for microbeam radiation therapy / Dimitri Reynard

DOI (Published version): 10.23889/Suthesis.53520

Abstract

Microbeam Radiation Therapy (MRT) is an emergent treatment modality that uses spatially fractionated synchrotron x-ray beams. MRT has been identified as a promising treatment concept that might be applied to patients with malignant cen-tral nervous system (CNS) tumors for whom, at the current stage o...

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Published: Swansea 2019
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Hugtenburg, Richard P. ; Estève, François
URI: https://cronfa.swan.ac.uk/Record/cronfa53520
first_indexed 2020-02-13T19:46:06Z
last_indexed 2020-09-17T03:16:48Z
id cronfa53520
recordtype RisThesis
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spelling 2020-02-13T16:27:25.6672321 v2 53520 2020-02-13 Accurate dosimetry for microbeam radiation therapy 2020-02-13 Microbeam Radiation Therapy (MRT) is an emergent treatment modality that uses spatially fractionated synchrotron x-ray beams. MRT has been identified as a promising treatment concept that might be applied to patients with malignant cen-tral nervous system (CNS) tumors for whom, at the current stage of development, no satisfactory therapy is available yet. The use of a fractionated beam allows a better skin sparing and a better tolerance of healthy tissue to high dose rates. MRT consists of a stereotactic irradiation with highly collimated, quasi-parallel array of narrow beams 50 µm wide spaced with 400 µm made of synchrotron generated x-rays at an energy ranging from 0 to 600 keV. The European Synchrotron Radiation Facility (ESRF) as an x-ray source allows a very small beam divergence and an extremely high dose rate. The dose deposited on the path of the primary photons (peak dose) of several hundred grays (Gy) is well tolerated by normal tissues and provides at the same time a higher therapeutic index for various tumor models in rodents. The high dose rate forces us to develop an accurate and reproducible dosimetry protocol to ensure the matching between the prescribed and the deliv-ered dose. MRT is by definition a non-conventional irradiation method, therefore the number of dosimetric errors becomes larger than in conventional treatments due to two reasons (i) the reference conditions recommended by the Association of Physicists in Medicine (AAPM) or the International Atomic Energy Agency (IAEA) cannot be established, (ii) the measurement of absorbed dose to water in composite fields is not standardized.This PhD is focused on bridging the gap between MC simulated values of output fac-tors (OF) and peak-to-valley dose ratios (PVDR) and experimental measurements. Several aspects of the irradiation setup such as insertion devices on the path of the x-ray beam are accounted for as well as the internal structure of the dosimeters. Each contribution to OF and PVDR is quantified to correct for the measurements. E-Thesis Swansea microdosimetry, monte-carlo simulations, microdiamond detector, microbeam, uncertainties evaluation 10 7 2019 2019-07-10 10.23889/Suthesis.53520 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME COLLEGE CODE Swansea University Hugtenburg, Richard P. ; Estève, François Doctoral Ph.D ABMU, Swansea University, Université Grenoble Alpes 2020-02-13T16:27:25.6672321 2020-02-13T16:27:25.6672321 Dimitri Reynard 1 53520__16572__15895a8e4cd849489364749b1ee80ad0.pdf Reynard_Dimitri_PhD_Thesis_Final _Redacted.pdf 2020-02-13T17:20:49.8072466 Output 6745179 application/pdf Redacted version - open access true false
title Accurate dosimetry for microbeam radiation therapy
spellingShingle Accurate dosimetry for microbeam radiation therapy
,
title_short Accurate dosimetry for microbeam radiation therapy
title_full Accurate dosimetry for microbeam radiation therapy
title_fullStr Accurate dosimetry for microbeam radiation therapy
title_full_unstemmed Accurate dosimetry for microbeam radiation therapy
title_sort Accurate dosimetry for microbeam radiation therapy
author ,
author2 Dimitri Reynard
format E-Thesis
publishDate 2019
institution Swansea University
doi_str_mv 10.23889/Suthesis.53520
document_store_str 1
active_str 0
description Microbeam Radiation Therapy (MRT) is an emergent treatment modality that uses spatially fractionated synchrotron x-ray beams. MRT has been identified as a promising treatment concept that might be applied to patients with malignant cen-tral nervous system (CNS) tumors for whom, at the current stage of development, no satisfactory therapy is available yet. The use of a fractionated beam allows a better skin sparing and a better tolerance of healthy tissue to high dose rates. MRT consists of a stereotactic irradiation with highly collimated, quasi-parallel array of narrow beams 50 µm wide spaced with 400 µm made of synchrotron generated x-rays at an energy ranging from 0 to 600 keV. The European Synchrotron Radiation Facility (ESRF) as an x-ray source allows a very small beam divergence and an extremely high dose rate. The dose deposited on the path of the primary photons (peak dose) of several hundred grays (Gy) is well tolerated by normal tissues and provides at the same time a higher therapeutic index for various tumor models in rodents. The high dose rate forces us to develop an accurate and reproducible dosimetry protocol to ensure the matching between the prescribed and the deliv-ered dose. MRT is by definition a non-conventional irradiation method, therefore the number of dosimetric errors becomes larger than in conventional treatments due to two reasons (i) the reference conditions recommended by the Association of Physicists in Medicine (AAPM) or the International Atomic Energy Agency (IAEA) cannot be established, (ii) the measurement of absorbed dose to water in composite fields is not standardized.This PhD is focused on bridging the gap between MC simulated values of output fac-tors (OF) and peak-to-valley dose ratios (PVDR) and experimental measurements. Several aspects of the irradiation setup such as insertion devices on the path of the x-ray beam are accounted for as well as the internal structure of the dosimeters. Each contribution to OF and PVDR is quantified to correct for the measurements.
published_date 2019-07-10T13:59:33Z
_version_ 1821414232467439616
score 11.543985

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