title: Absorbed dose to water measurements in the SOBP of a clinical carbon-ion beam using water calorimetry
creator: Holm, Kim Marina
subject: ddc-530
subject: 530 Physics
description: Up til now, the dosimetry in terms of absorbed dose to water in carbon-ion beams has not reached the same level of accuracy as in high-energy photon beams. This is strongly influenced by the standard uncertainty of the beam quality correction factor kQ. Due to a lack of experimental data, kQ is mainly based on theoretical calculations showing a three times higher uncertainty than in photon beams. In order to reduce this standard uncertainty, experimental kQ factors have been determined for the entrance channel of a monoenergetic carbon-ion beam. Within this thesis, kQ factors are now presented for the spread-out Bragg peak (SOBP) of a carbon-ion beam for the first time. Therefore, the absorbed dose to water in a previously well-characterized irradiation field was determined by means of water calorimetry. To be able to perform these measurements in scanned carbon-ion beams, the SOBP was passively modulated using a static 2D range modulator. Based on the water calorimetric measurements, ionization chambers could be calibrated directly, determining chamber-specific kQ factors with a relative standard uncertainty of 0.7 %. This significant reduction in uncertainty compared to calculated values gives the chance to drastically decrease the overall uncertainty in IC-based dosimetry for clinical carbon-ion beams.
date: 2021
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/30036/7/Thesis_Holm_final.pdf
identifier: DOI:10.11588/heidok.00030036
identifier: urn:nbn:de:bsz:16-heidok-300367
identifier:   Holm, Kim Marina  (2021) Absorbed dose to water measurements in the SOBP of a clinical carbon-ion beam using water calorimetry.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/30036/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng