Comparison of computed tomography- And magnetic resonance imaging-based target delineation for cervical cancer brachytherapy

Abstract

Purpose: The objective of this study was to compare and assess the accuracy of computed tomography (CT)-based target delineation with that of magnetic resonance imaging (MRI)-based on high-dose-rate brachytherapy (HDR-BT) for patients with cervical cancer. Material and methods: Data of 20 patients with locally advanced cervical cancer were collected and evaluated. Dimensions, conformity, and dose parameters of high-risk clinical target volume (CTVHR) as well as D0.1cc, D1cc, and D2cc of organs at risk (OARs) based on MRI were compared with those based on CT. Results: Average age of 20 patients included was 57.8 years. Width, thickness, and volumes of CT-based CTVHR (CTVHR-CT) were significantly overestimated compared with those of MRI-based CTVHR (CTVHR-MR). Mean values of dice similarity coefficient (DSC), Hausdorff distance (HD), and centroid distance (DV) of CTVHR were 0.82 cm, 0.96 cm, and 0.35 cm, respectively. Dose values of CTVHR-CT were significantly lower compared with those of CTVHR-MR. Concerning OARs, geometrical and dosimetric values on CT were comparable to those on MRI. Conclusions: The delineated ranges of CTVHR were significantly over-estimated on CT compared with MRI. D98 and D90 of CTVHR-CT were lower than CTVHR-MR. DSC and DV of CTVHR and CTVIR were similar to each other; however, there was a difference in terms of HD. CT images regarding pre-BT MR images for delineating were not enough and MRI fusion is still required.