Image-Guided Volumetric Modulated Arc Therapy (IG-VMAT) for Prostate Cancer

Abstract

Intensity modulated radiation therapy (IMRT) remains the prevailing radiation treatment modality for localized prostate cancer. However, IMRT has three pronounced deficiencies: an elevated MU, a reduced MU-to-c-Gy coefficient, and the inability to track target motion. To address these issues, we have developed a novel radiation treatment technique, called the image-guided volumetric modulated radiation therapy (IG-VMAT) for the treatment of localized prostate cancer. In IG-VMAT approach, the image-guided target localization is achieved through point-based image registration using implanted gold-seed markers as a similarity measure, MU reduction is realized by using beam aperture-based inverse optimization, and the desired dose distribution is obtained through a synergistic modulation of MLC linear speed, temporal dose rate, and LINAC gantry angular speed. Our preliminary clinical data indicate that IG-VMAT can produce equal or better treatment plans than IMRT, reduce mean beam-on time by 45.8%, and achieve 1 mm accuracy in target localization.