Marieke van Son

167 RE-SALVAGE FOCAL HDR-BT Figure 3 – Dose distribution first MRI-guided focal salvage HDR-BT. Transversal plane (upper magnetic resonance (MR) image) and sagittal plane (lower MR image) showing delineations of the bladder (purple), urethra (yellow), rectum (green), prostate (red), and gross tumor volume (GTV, blue) in the right dorsal peripheral zone and the right seminal vesicle. The images show signal voids from the catheters and previously implanted iodine 125 seeds. On the sagittal image, one of the catheters is visible within the GTV. In this case, the clinical target volume (CTV) was considered equal to the GTV because there was mainly seminal vesicle invasion. Radiation dose is displayed in colors, with red representing 19Gy and green representing 9.5Gy. 9