Journal article
Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
Journal of contemporary brachytherapy, Vol.5(4), pp.250-257
01/01/2013
DOI: 10.5114/jcb.2013.39453
PMCID: PMC3899640
PMID: 24474977
Abstract
Purpose: To quantify the dosimetric impact of applicator displacements and applicator reconstruction-uncertainties through simulated planning studies of virtual applicator shifts.
Material and methods: Twenty randomly selected high-dose-rate (HDR) titanium tandem-and-ovoid (T&O) plans were retrospectively studied. MRI-guided, conformal brachytherapy (MRIG-CBT) plans were retrospectively generated. To simulate T&O displacement, the whole T&O set was virtually shifted on treatment planning system in the cranial (+) and the caudal (-) direction after each dose calculation. Each shifted plan was compared to an unshifted plan. To simulate T&O reconstruction-uncertainties, each tandem and ovoid was separately shifted along its axis before performing the dose calculation. After the dose calculation, the calculated isodose lines and T&O were moved back to unshifted T&O position. Shifted and shifted-back plan were compared.
Results: Regarding the dosimetric impact of the simulated T&O displacements, rectal D-2cc values were observed as being the most sensitive to change due to T&O displacement among all dosimetric metrics regardless of point A (p < 0.013) or MRIG-CBT plans (p < 0.0277). To avoid more than 10% change, +/- 1.5 mm T&O displacements were accommodated for both point A and MRIG-CBT plans. The dosimetric impact of T&O displacements on sigmoid (p < 0.0005), bladder (p < 0.0001), HR-CTV (p < 0.0036), and point A (p < 0.0015) were significantly larger in the MRIG-CBT plans than point A plans. Regarding the dosimetric impact of T&O reconstruction-uncertainties, less than +/- 3.0 mm reconstruction-uncertainties were also required in order to avoid more than 10% dosimetric change in either the point A or MRIG-CBT plans.
Conclusions: The dosimetric impact of simulated T&O displacements was significantly larger in the MRIG-CBT plans than in the point A plans. Either +/- 3 mm T&O displacement or a +/- 4.5 mm T&O reconstruction-uncertainty could cause greater than 10% dosimetric change for both point A plans and MRIG-CBT plans.
Details
- Title: Subtitle
- Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer
- Creators
- Joshua Schindel - Biomedical Engineering Department.Winson Zhang - University of IowaSudershan K. Bhatia - University of IowaWenqing Sun - University of IowaYusung Kim - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of contemporary brachytherapy, Vol.5(4), pp.250-257
- DOI
- 10.5114/jcb.2013.39453
- PMID
- 24474977
- PMCID
- PMC3899640
- NLM abbreviation
- J Contemp Brachytherapy
- ISSN
- 1689-832X
- eISSN
- 2081-2841
- Publisher
- Termedia Publishing House Ltd
- Number of pages
- 8
- Grant note
- Varian Medical System, Inc. P30CA086862 / NATIONAL CANCER INSTITUTE; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Cancer Institute (NCI)
- Language
- English
- Date published
- 01/01/2013
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984312960502771
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