@Article{Schindel2013,
journal="Journal of Contemporary Brachytherapy",
issn="1689-832X",
volume="5",
number="4",
year="2013",
title="Original paperDosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer",
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 D2cc 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.",
author="Schindel, Joshua
and Zhang, Winson
and Bhatia, Sudershan K.
and Sun, Wenqing
and Kim, Yusung",
pages="250--257",
doi="10.5114/jcb.2013.39453",
url="http://dx.doi.org/10.5114/jcb.2013.39453"
}