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

Abstract

PurposeThe 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 methodsData 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.ResultsAverage 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 (ΔV) 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.ConclusionsThe 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 ΔV 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.