Purpose: To study the effectiveness of Space OAR-View gel as volume to match to during the Cone Beam CT acquisition as part of image guidance and comparing the matching to fiducial markers for patients with prostate cancer.
Methods: From September 2020 we selected 12 patients with the following criteria: Age < 80 years; P.S. 0-1; Stage T1a – T2b; Gleason Score 3+3 with PSA ≤15 ng/ml. The patients selected did not undergo prior radiation therapy or surgery to the pelvis area. Space OAR-View by Boston Scientific was placed between anterior rectal wall and posterior prostate and 4 fiducial markers were implanted using a trans perineal approach. Each patient was immobilized in a supine position and simulated with 2.5mm CT scan with empty bladder. Contours of critical structures included the Space-OAR–View gel. Image guided radiation therapy using both cone beam CT (CBCT) and KV/KV fiducial markers match were used daily to assess the correlation and comparison between the Space-OAR-View contoured structure with respect to the Markers. Gel volume was also evaluated for the duration of the treatments.
Results: Review of our preliminary data suggests that the use of Space OAR-View gel as structure to match to after cone beam CT is a valid and accurate methodology that helps the users during the fusion; it presents benefits over matching to other structures such as anterior rectal wall due to day to day variations and changes; it correlated well with a comparison to the fiducial markers match. We have also noticed a small variation in the Space OAR-View volume and more data is needed to validate our observations.
Conclusion: Our study procedural imaging prostate patients with CBCT and matching to the gel findings may benefit patients with prostate fossa whom don't get fiducial markers and CBCT can be used with the gel.
Not Applicable / None Entered.