International Journal of Hematology and Oncology 2019, Vol 29, Num 4 Page(s): 227-237
A Comparison of Magnetic Resonance and Computed Tomography Imaging Based Target-Volume Definition and Interfraction Variations of Treatment Planning Parameters (D90 HR-CTV, D2cc for OARs) During Image Guided Adaptive Brachytherapy for Cervical Cancer

Hazim Orhan KIZILKAYA1, Ayse Kutluhan DOGAN1, Zedef DAG2, Halime Can TURAN3, Donay Unluer AKSAN4, Nazmiye Deniz ARSLAN2

1Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Department of Radiation Oncology, Istanbul, TURKEY
2Health Sciences University, Yedikule Chest Diseases and Thoracic Surgery Training and Research Hospital, Department of Radiation Oncology, Istanbul, TURKEY
3Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Department of Radiation Oncology,Medical Physics, Istanbul, TURKEY
4Health Sciences University, Samsun Training and Research Hospital, Department of Radiation Oncology, Samsun, TURKEY

Keywords: Cervical cancer, Image-guided brachytherapy, MRI- guided brachytherapy, CT- guided brachytherapy
The aim of this study is to compare computed tomography (CT) and magnetic resonance imaging (MRI) based high-risk clinical target volume (HR-CTV) contours in brachytherapy (BT) for cervical cancer in order to identify patients who may benefit most from MRI-based planning. We also analyzed interfractions variations of the organ at risk (OAR) affects the given doses. Twenty patients who had a pretreatment diagnostic MRI were included. We delineated the HR-CTV and OARs on the CT- and MRI- based scans independently for each patient. Dose-volume parameters D90 HR-CTV and D2cc OARs in CT and MRI plannings were determined and compared; the effect of time on the natural mobility was analyzed. The mean CT and MRI HR-CTV were 28.4 ±11 cm3; 19.0±8.1, (p< 0.001), respectively. The mean EQD2 of CT and MRI HR-CTV were 93.2 ±1.1Gy ;92.7±0.6 Gy, (p< 0.041). The mean D2cc of the rectum, bladder, and sigmoid in CT-based plans were higher (17%, 13.3% and 22.8%, respectively) then MRI-based plannings and significant differences were found in patients between the D2cc of rectum (p< 0.001) and sigmoid (p< 0.001). Furthermore, the interfractions volume variations and mean EQD2 doses for all OARs and HR-CTV were statistically insignificant in both image-guided plannings. The use of MRI-based BT for target localization in cervical cancer provides an improved accuracy and precision of the tumor volume as well as a similar dose coverage to the HR-CTV and better minimize the D2cc values of OARs, when it is compared with CT -based planning.