Geometric discrepancy of image-guided radiation therapy in patients with prostate cancer without implanted fiducial markers using a commercial pseudo-CT generation method.

Geometric discrepancy of image-guided radiation therapy in patients with prostate cancer without implanted fiducial markers using a commercial pseudo-CT generation method.
Phys Med Biol. 2019 Jan 29;:
Authors: Kan H, Eguchi Y, Tsuchiya T, Kondo T, Kitagawa Y, Mekata Y, Fukuma H, Yoshida R, Kasai H, Kunitomo H, Hirose Y, Shibamoto Y
Abstract
MR-only simulations provide pseudo-CT images which are segmented into 5 kinds of tissues from DIXON-based images. However, it is difficult to register pseudo-CT images to cone-beam CT (CBCT) images collected for image-guided radiation therapy (IGRT), because of the lack of contrasts among tissues. We validated gaps of IGRT between pseudo-CT or planning CT and CBCT for patients without implanted markers. We also propose calcification-assisted registration for MR-only simulation.
 We conducted retrospective analyses to verify the registration accuracy in 15 patients who underwent volumetric modulated arc therapy for prostate cancer. They underwent planning CT and pseudo-CT. Pseudo-CT images after deformable image registration (DIR) to planning CT images were rendered automatic pelvic bone matching to CBCT images. Patient positions on the pseudo-CT images after DIR were shifted on the basis of tissues around the prostate. We compared registration gaps between the images of planning CT and pseudo-CT with DIR, assuming that the tissue-based matching between the planning CT and CBCT was the gold...

Source: Physics in Medicine and Biology - January 29, 2019 Category: Physics Authors: Kan H, Eguchi Y, Tsuchiya T, Kondo T, Kitagawa Y, Mekata Y, Fukuma H, Yoshida R, Kasai H, Kunitomo H, Hirose Y, Shibamoto Y Tags: Phys Med Biol Source Type: research