A Monte Carlo dosimetry study of vaginal 192Ir brachytherapy applications with a shielded cylindrical applicator set

Lymperopoulou, G; Pantelis, E; Papagiannis, P; Rozaki-Mavrouli, H; Sakelliou, L; Baltas, D; Karaiskos, P

dc.contributor.author	Lymperopoulou, G	en
dc.contributor.author	Pantelis, E	en
dc.contributor.author	Papagiannis, P	en
dc.contributor.author	Rozaki-Mavrouli, H	en
dc.contributor.author	Sakelliou, L	en
dc.contributor.author	Baltas, D	en
dc.contributor.author	Karaiskos, P	en
dc.date.accessioned	2014-03-01T01:19:45Z
dc.date.available	2014-03-01T01:19:45Z
dc.date.issued	2004	en
dc.identifier.issn	0094-2405	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15701
dc.subject	Monte Carlo	en
dc.subject.classification	Radiology, Nuclear Medicine & Medical Imaging	en
dc.subject.other	iridium 192	en
dc.subject.other	tungsten	en
dc.subject.other	article	en
dc.subject.other	geometry	en
dc.subject.other	Monte Carlo method	en
dc.subject.other	neutron dosimetry	en
dc.subject.other	priority journal	en
dc.subject.other	radiation applicator	en
dc.subject.other	radiation dose distribution	en
dc.subject.other	radiation shield	en
dc.subject.other	radioisotope therapy	en
dc.subject.other	treatment planning	en
dc.subject.other	vagina cancer	en
dc.subject.other	Body Burden	en
dc.subject.other	Brachytherapy	en
dc.subject.other	Female	en
dc.subject.other	Humans	en
dc.subject.other	Iridium Radioisotopes	en
dc.subject.other	Models, Biological	en
dc.subject.other	Models, Statistical	en
dc.subject.other	Monte Carlo Method	en
dc.subject.other	Radiation Protection	en
dc.subject.other	Radiometry	en
dc.subject.other	Radiotherapy Dosage	en
dc.subject.other	Radiotherapy Planning, Computer-Assisted	en
dc.subject.other	Rectal Neoplasms	en
dc.subject.other	Relative Biological Effectiveness	en
dc.subject.other	Reproducibility of Results	en
dc.subject.other	Risk Assessment	en
dc.subject.other	Risk Factors	en
dc.subject.other	Sensitivity and Specificity	en
dc.subject.other	Vaginal Neoplasms	en
dc.title	A Monte Carlo dosimetry study of vaginal 192Ir brachytherapy applications with a shielded cylindrical applicator set	en
heal.type	journalArticle	en
heal.identifier.primary	10.1118/1.1810233	en
heal.identifier.secondary	http://dx.doi.org/10.1118/1.1810233	en
heal.language	English	en
heal.publicationDate	2004	en
heal.abstract	A durable recommendation for brachytherapy treatment planning systems to account for the effect of tissue, applicator and shielding material heterogeneities exists. As different proposed approaches have not been integrated in clinical treatment planning routine yet, currently utilized systems disregard or, most commonly, do not fully account for the aforementioned effects. Therefore, it is of interest to evaluate the efficacy of current treatment planning in clinical applications susceptible to errors due to heterogeneities. In this work the effect of the internal structure as well as the shielding used with a commercially available cylindrical shielded applicator set (Nucletron part # 084.320) for vaginal and rectum treatments is studied using three-dimensional Monte Carlo simulation for a clinical treatment plan involving seven source dwell positions of the classic microSelectron HDR Ir-192 source. Results are compared to calculations of a treatment planning system (Plato BPS v. 14.2.7), which assumes homogeneous water medium and applies a constant, multiplicative transmission factor only at points lying in the shadow of the shield. It is found that the internal structure of the applicator (which includes stainless steel, air and plastic materials) with no shield loaded does not affect the dose distribution relative to homogeneous water. In the unshielded side of the applicator with a 90degrees, 180degrees, or 270degrees tungsten alloy shield loaded, an overestimation of treatment planning system calculations relative to Monte Carlo results was observed which is both shield and position dependent. While significant (up to 15%) at increased distances, which are not of major clinical importance, this overestimation does not affect dose prescription distances by more than 3%. The inverse effect of approx. 3% dose increase at dose prescription distances is observed for stainless steel shields. Regarding the shielded side of the applicator, it is shown that the default treatment planning system transmission factors for tungsten alloy result in a consistent dose overestimation thus constituting a safe approach given the nature of associated clinical applications. Stainless steel is shown to be an ineffective shielding material with transmission factors reaching up to 0.68 at increased distances irrespective of shield geometry. (C) 2004 American Association of Physicists in Medicine.	en
heal.publisher	AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS	en
heal.journalName	Medical Physics	en
dc.identifier.doi	10.1118/1.1810233	en
dc.identifier.isi	ISI:000225372300018	en
dc.identifier.volume	31	en
dc.identifier.issue	11	en
dc.identifier.spage	3080	en
dc.identifier.epage	3086	en