An analytical dosimetry model as a step towards accounting for inhomogeneities and bounded geometries in 192Ir brachytherapy treatment planning

Anagnostopoulos, G; Baltas, D; Karaiskos, P; Pantelis, E; Papagiannis, P; Sakelliou, L

dc.contributor.author	Anagnostopoulos, G	en
dc.contributor.author	Baltas, D	en
dc.contributor.author	Karaiskos, P	en
dc.contributor.author	Pantelis, E	en
dc.contributor.author	Papagiannis, P	en
dc.contributor.author	Sakelliou, L	en
dc.date.accessioned	2014-03-01T01:18:38Z
dc.date.available	2014-03-01T01:18:38Z
dc.date.issued	2003	en
dc.identifier.issn	0031-9155	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15117
dc.subject	Treatment Planning	en
dc.subject.classification	Engineering, Biomedical	en
dc.subject.classification	Radiology, Nuclear Medicine & Medical Imaging	en
dc.subject.other	Attenuation	en
dc.subject.other	Mathematical models	en
dc.subject.other	Monte Carlo methods	en
dc.subject.other	Photons	en
dc.subject.other	Water	en
dc.subject.other	Dose rate	en
dc.subject.other	Dosimetry	en
dc.subject.other	alloy	en
dc.subject.other	iridium 192	en
dc.subject.other	tungsten	en
dc.subject.other	accuracy	en
dc.subject.other	analytic method	en
dc.subject.other	article	en
dc.subject.other	brachytherapy	en
dc.subject.other	calculation	en
dc.subject.other	density	en
dc.subject.other	dosimetry	en
dc.subject.other	energy absorption	en
dc.subject.other	evaluation	en
dc.subject.other	geometry	en
dc.subject.other	light scattering	en
dc.subject.other	model	en
dc.subject.other	Monte Carlo method	en
dc.subject.other	phantom	en
dc.subject.other	photon	en
dc.subject.other	prediction	en
dc.subject.other	priority journal	en
dc.subject.other	radiation dose	en
dc.subject.other	treatment planning	en
dc.subject.other	Algorithms	en
dc.subject.other	Anisotropy	en
dc.subject.other	Brachytherapy	en
dc.subject.other	Humans	en
dc.subject.other	Iridium Radioisotopes	en
dc.subject.other	Linear Energy Transfer	en
dc.subject.other	Models, Biological	en
dc.subject.other	Radiometry	en
dc.subject.other	Radiopharmaceuticals	en
dc.subject.other	Radiotherapy Dosage	en
dc.subject.other	Radiotherapy Planning, Computer-Assisted	en
dc.subject.other	Reproducibility of Results	en
dc.subject.other	Scattering, Radiation	en
dc.subject.other	Sensitivity and Specificity	en
dc.title	An analytical dosimetry model as a step towards accounting for inhomogeneities and bounded geometries in 192Ir brachytherapy treatment planning	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0031-9155/48/11/310	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0031-9155/48/11/310	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	A simple analytical dose rate calculation model based on primary and scatter separation that treats 192 IF as a monoenergetic source by use of appropriate attenuation and mass energy absorption coefficients is documented for accurate dosimetry in water. This model is then generalized and tested for use in any homogeneous tissue material of radiobiological interest using scatter to primary ratios calculated in water with a material density scaling to account for the difference in the scattering properties of these materials and water. The potential of the analytical model for predicting the effect of the interference of an inhomogeneity is then evaluated by comparison with corresponding Monte Carlo calculations. It is found that regardless of the inhomogeneity dimensions and position relative to the source, the model is capable of increased accuracy (better than 2%) in calculating the primary dose rate at any point not only for low-Z tissue materials but also for high-Z shielding materials where a severe hardening of the primary photons occurs. Overall, for low-Z tissue inhomogeneities the proposed model succeeds in correcting dosimetry results towards the right direction compared to commercial treatment planning systems that currently ignore the effect of phantom dimensions and inhomogeneity interference. Regarding high-Z shielding materials the proposed model accurately predicts the dose reduction just beyond the inhomogeneity (for example it predicts a dose reduction of 47% just behind a tungsten alloy cylinder of 1 cm diameter and 2 mm thickness placed at 1.4 cm away from an Ir-192 source, in agreement with corresponding results in the literature) but does not account for the increasing contribution of the laterally scattered photons with increasing distance from the bounded inhomogeneity.	en
heal.publisher	IOP PUBLISHING LTD	en
heal.journalName	Physics in Medicine and Biology	en
dc.identifier.doi	10.1088/0031-9155/48/11/310	en
dc.identifier.isi	ISI:000183562000010	en
dc.identifier.volume	48	en
dc.identifier.issue	11	en
dc.identifier.spage	1625	en
dc.identifier.epage	1647	en