eprintid: 22822
rev_number: 16
eprint_status: archive
userid: 3067
dir: disk0/00/02/28/22
datestamp: 2017-06-14 12:12:32
lastmod: 2017-06-28 09:14:43
status_changed: 2017-06-14 12:12:32
type: masterThesis
metadata_visibility: show
creators_name: Dal Bello, Riccardo
title: Degradation of proton and carbon Bragg peaks due to density inhomogeneities
subjects: ddc-530
divisions: i-130001
divisions: i-850300
adv_faculty: af-05
cterms_swd: Hadrontherapy
cterms_swd: Bragg Peak
cterms_swd: Monte Carlo
abstract: Current analytical treatment planning of radiotherapy with protons and heavier ions neglect degradation of the sharp distal dose falloff (Bragg peak, BP) caused by inhomogeneous tissue. There is no appropriate model of this effect - which in turn allowed reduction of related dose deposition uncertainties. This thesis develops a comprehensive analytical model of the degradation resulting from static lung parenchyma. To do so, it adopts Monte Carlo (MC) simulations, validated by a series of transmission experiments on lung-like phantoms. Fluctuations in the water equivalent thickness (WET) were found the major degradation factor, contributing more than 75% (40%) to the distal falloff widening for a carbon (proton) BP - while energy and particle type were found to have no considerable impact. Also, it was found that the plateau of a clinical spread-out BP remains unaffected but the distal falloff is degraded and that the impact on the biological effect is driven by changes to the physical dose. The model was parametrized with respect to lung specific parametr (alveolar dimension and tissue density) and breathing state parameters (thickness traversed, air filling). Formulation of a Gaussian filter provided a unified, compact and complete description that can readily be implemented in a treatment planning system.
date: 2017
id_scheme: DOI
id_number: 10.11588/heidok.00022822
ppn_swb: 1659230128
own_urn: urn:nbn:de:bsz:16-heidok-228226
date_accepted: 2016-10
advisor: HASH(0x55fc36c30cb8)
language: eng
bibsort: DALBELLORIDEGRADATIO2017
full_text_status: public
thesis_type: Master
citation:   Dal Bello, Riccardo  (2017) Degradation of proton and carbon Bragg peaks due to density inhomogeneities.  [Master's thesis]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/22822/1/thesis_database.pdf