Dosimetric Comparison between High Dose Rate Brachytherapy Boost and Volumetric Arc Therapy Boost in Locally Advanced Cancer Cervix

AbstractConcurrent chemoradiotherapy is considered the standard treatment for the locally advanced cancer cervix (LACC). Radiotherapy is commonly administered by a three-dimensional conformal radiotherapy (3DCRT) approach followed by brachytherapy (BT). High dose rate (HDR) BT is commonly administered; however, several drawbacks exist including invasive technique, pain, requirement of anesthesia, and operative risks. We assessed the dosimetric difference between the HDR BT and the volumetric modulated arc therapy (VMAT) boost in those patients. Ten patients were selected retrospectively with LACC and all received whole pelvis radiotherapy followed by BT boost of 7 Gy in three fractions. The computed tomography (CT) image was transferred to the Varian system for the VMAT plan while the one with the applicator was transferred to the Sagi planning system and the high-risk clinical target volume (HR-CTV), bladder, rectum, sigmoid, and small bowel were delineate with a margin of 5 mm were added to the CTV to create the planning target volume (PTV). The D90 for the PTV in VMAT boost was lower than received by the HR-CTV in the BT boost. Mean volume of the PTV was higher than that of the HR-CTV. The D2cc was higher in VMAT for bladder, sigmoid, and rectum while the D2cc for the small bowel in BT was higher compared with the VMAT. The VMAT is an option that exists for patients who refuse BT or cannot tolerate it, or in case of nonavailability of BT or a nonworking machine.