Marieke van Son

91 MRI-GUIDED ULTRAFOCAL SALVAGE HDR-BRACHYTHERAPY Treatment characteristics Median nine brachytherapy catheters were used for the implant (range 5-14). The CTV D95% ≥19 Gy prescription dose was achieved in 42%, with a median administered dose of 18.8 Gy (range 11.3-23 Gy). The CTV D90% >17 Gy lower threshold was achieved in 90%, with a median of 20.4 Gy (range 13.5-24.9 Gy). The main reason for underdosing the CTV was to refrain from exceeding dose constraints for the organs at risk. Median urethral D10% was 14.8 Gy (range 3.1-18.2), median bladder D1cc was 8.2 Gy (range 1.3-13.6) and median rectum D1cc was 10 Gy (range 2.3-12.2). The median percentage of target volume receiving 100%, 150% and 200% of the prescribed dose (CTV V100%, V150%, V200%) was 95%, 57% and 25%, respectively. Toxicity Figure 1 shows physician-graded GU, GI and erectile toxicity. GU toxicity scoring in- cluded the items hematuria, urinary frequency, urinary incontinence, urinary retention, urinary tract pain and cystitis. Severe (grade 3) toxicity occurred in one patient (2%) after 24 months follow-up. The patient underwent surgical dilation for an obstructive urethral stricture, after which he was left with urinary incontinence, requiring several incontinence pads per day. New-onset grade 2 GU toxicity was seen in 26 patients (52%), among which the prescription of medication for urinary frequency in 21 patients, use of incontinence pads for occasional urinary leakage in three patients, mild signs of cystitis in one patient and mild postmictional residue in one patient. 19/21 patients required chronic use (until last follow-up) of urinary medication and 1/3 patients re- quired chronic use of pads. For GI toxicity, the items abdominal pain, diarrhea, enterocolitis, fecal incontinence, flatulence, hemorrhoids, proctitis, rectal fistula, rectal hemorrhage and rectal pain were graded. No grade 3 GI toxicity occurred. New-onset grade 2 GI toxicity occurred in two patients (4%): one had transient rectal hemorrhage and one developed symptomatic hemorrhoids. Pre-treatment grade 3 ED (severe dysfunction with insufficient effect from erectile aids) was present in nine patients (18%). New-onset grade 3 ED developed in 11 patients (22%), and new-onset grade 2 ED (dysfunction, but with sufficient effect from erectile aids) developed in another 11 patients (22%). 5