Deformable image registration for contour propagation from CT to cone-beam CT scans in radiotherapy of prostate cancer

• DOI: 10.3109/0284186x.2011.577806
• Publication Date: 2011-11-25T10:27:11Z
• Authors: Maria Thor; Jørgen B. B. Pete...; Lise Bentzen; Morten Høyer; Ludvig Paul Muren
• Keywords: Cone-Beam CT; External beam radiotherapy; Image registration; Image-guided radiation therapy

Background and purpose. Daily organ motion occurring during the course of radiotherapy in pelvic region leads to uncertainties doses delivered tumour organs at risk. Motion patterns include both volume shape changes, calling for deformable image registration (DIR), approaches involving dose accumulation adaptation. In this study, we tested performance a DIR application contour propagation from treatment planning computed tomography (pCT) repeat cone-beam CTs (CBCTs) set prostate cancer patients. Material methods. The prostate, rectum bladder were delineated pCT six eight CBCTs each five contours propagated onto corresponding CBCT using Multi-modality Image Registration Segmentation application, resulting 36 registrations. Prior DIR, rigid was performed. algorithm used based on 'demons' it examined quantitatively Dice similarity coefficient (DSC) qualitatively as visual slice-by-slice scoring by radiation oncologist grading deviations and/or distance relative anatomy. Results. average DSC (range) over all scans patients 0.80 (0.65–0.87) 0.77 (0.63–0.87) 0.73 (0.34–0.91) bladder, while DSCs registrations (0.65–0.86), 0.71 (0.55–0.82) 0.64 (0.33–0.87). percentage good/acceptable quality 45% prostate; 20% 33% bladder. For there an association between different scores qualitative evaluation. Conclusions. improved compared only. Still, large fraction unacceptable. sub-optimal usability adaptation purposes is therefore likely benefit improvements algorithm.