Integral transport based deterministic brachytherapy dose calculations

dc.contributor.advisor	Lester Schmerr
dc.contributor.advisor	Joseph Gray
dc.contributor.author	Zhou, Chuanyu
dc.contributor.department	Aerospace Engineering
dc.date	2018-08-25T02:16:07.000
dc.date.accessioned	2020-06-30T07:18:35Z
dc.date.available	2020-06-30T07:18:35Z
dc.date.copyright	Thu Jan 01 00:00:00 UTC 2004
dc.date.issued	2004-01-01
dc.description.abstract	<p>Brachytherapy usually refers to a category of procedures where radiation sources are implanted into the tumor or into its close vicinity to deliver high radiation doses into the tumor for a therapy. A feedback about the dose rate distribution during the surgery is desired to guarantee the dose coverage and the success of a treatment. Calculation speed is crucial in this attempt and traditional Monte Carlo methods are not suitable for this purpose.;We developed a deterministic algorithm for computing three dimensional brachytherapy dose distributions. The deterministic algorithm has been based on the integral transport equation. The integral transport equation is solved by the Neumann Series and spatial, angular and energy discretizations. Source scheme and transport scheme are the two steps to calculate the scattered photon flux. The algorithm provided us a capability of computing dose distributions for multiple isotropic point and/or volumetric sources in a homogenous/heterogeneous medium. Two seed models, model 2301 and model 6711 were studied. The algorithm results for these two seeds have been benchmarked against the results from literatures and MCNP calculation. We have included fluorescence radiation physics to handle the silver fluorescence in seed model 6711. We designed and implemented a parallel algorithm to speed up the calculations. The introduction of parallel computing capability provided a means to compute the dose distribution for multiple seeds in a simultaneous manner.;We can compute dose distributions for a large set of seeds without resorting to the superposition methods, which is current technique to calculate overall dose distribution from multiple seeds. This provided a way to study strong heterogeneity and shadow effects induced by the presence of multiple seeds in an interstitial brachytherapy implant. By studying a 81 seeds problem, we observed that superposition of single seeds dose distribution can lead to at least 5~10% overestimation around implanted seeds. This provided more evidence that the shadow effect has significant impacts on the dose distribution and should be considered in the brachytherapy dosimetry.</p>
dc.format.mimetype	application/pdf
dc.identifier	archive/lib.dr.iastate.edu/rtd/1214/
dc.identifier.articleid	2213
dc.identifier.contextkey	6091414
dc.identifier.doi	https://doi.org/10.31274/rtd-180813-12589
dc.identifier.s3bucket	isulib-bepress-aws-west
dc.identifier.submissionpath	rtd/1214
dc.identifier.uri	https://dr.lib.iastate.edu/handle/20.500.12876/65475
dc.language.iso	en
dc.source.bitstream	archive/lib.dr.iastate.edu/rtd/1214/r_3158389.pdf\|\|\|Fri Jan 14 19:13:48 UTC 2022
dc.subject.disciplines	Biomedical Engineering and Bioengineering
dc.subject.disciplines	Medical Biophysics
dc.subject.disciplines	Radiology
dc.subject.keywords	Aerospace engineering
dc.subject.keywords	Engineering mechanics
dc.title	Integral transport based deterministic brachytherapy dose calculations
dc.type	article
dc.type.genre	dissertation
dspace.entity.type	Publication
relation.isOrgUnitOfPublication	047b23ca-7bd7-4194-b084-c4181d33d95d
thesis.degree.level	dissertation
thesis.degree.name	Doctor of Philosophy

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