Proposal of a post-prostatectomy clinical target volume based on pre-operative MRI: volumetric and dosimetric comparison to the RTOG guidelines

• DOI: 10.1186/s13014-014-0303-6
• Publication Date: 2014-12-22T12:52:23Z
• Authors: Jennifer Croke; Jillian Maclean; Balazs Nyiri; Yan Li; Kyle Malone; Leonard Avruch; Cathleen Kayser; Shawn Malone
• Keywords: Male; Organs at Risk; Prostatectomy; Research; Radiotherapy Planning, Computer-Assisted; 610; Prostatic Neoplasms; Radiotherapy Dosage; Magnetic Resonance Imaging; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Oncology; Radiology Nuclear Medicine and imaging; Practice Guidelines as Topic; Preoperative Care; Humans; Neoplasm Recurrence, Local; Radiotherapy, Conformal

Recurrence rates following radiotherapy for prostate cancer in the post-operative adjuvant or salvage setting remain substantial. Previous work from our institution demonstrated that published bed CTV guidelines frequently do not cover pre-operative MRI defined prostate. Inadequate target delineation may contribute to high recurrence rates, but increasing volumes increase dose organs at risk. We propose delineating post-prostatectomy based upon an individual's co-registered MRI. MRI-based CTVs and PTVs were compared those created using RTOG 30 patients. Contours analysed terms of absolute volume, intersection volume (Jaccard Index) ability meet RADICALS QUANTEC rectal bladder constraints (tomotherapy IMRT plans with PTV coverage V98% ≥98%). was a mean 18.6% larger than RTOG: 138 cc (range 72.3 - 222.2 cc), 116.3 62.1 176.6 (p < 0.0001). The difference only 4.6%: 386.9 254.4 – 551.2), 370 232.3 501.6) = 0.05). Jaccard Index representing between 0.72 0.84 PTVs. Both criteria had similar constraints. Rectal DVH: 77% cases passed all 37% criteria; versus 73% 40% 1.0 both). Bladder DVH; 47% 67% criteria, 57% 60% 0.61for RADICALS, p 0.79 QUANTEC). spares more lower anterior wall increases superior lateral walls. contours patient's improve without substantially size bladder/ rectum guidelines. Further evaluation whether use improves local control is warranted.