Dosimetry and Treatment Descriptions Using the First Completely Automated Stereotactic Intracranial Radiosurgery Rotating Gamma Ray Unit in America.

Abstract

Introduction The objective is to report the dosimetry and safety profiles of the first fully automatized rotating gamma ray unit for intracranial radiosurgery in America. Methods Dosimetry tests were conducted by our institution using the standard of examination and calibration and the Intelligent γ Radiometer of the China Research Institute of Measurement. The phantom and dosimetry tests were performed by the Outreach Physics Section of MD Anderson Cancer Center and the Anchorage Radiation Therapy Center using the Radiation Therapy Oncology Group (RTOG) radiosurgery quality assurance guidelines. Clinically, 233 patients were treated. Results Mechanical precision was 0.16 mm and the offset registered at the phantom on all axes was 0.0. The ratio of the dose to the center was 0.97 (0.95-1.05), the ratio of the treated volume was 0.95 (0.75-1.25), the ratio of the measured treated volume to the volume of the target was 1.29 (1.00-2.00), the ratio of the minimal dose to the dose prescribed was 1.05 (>0.90), with a treated volume of 0.95 (0.75-1.25) and a minimum dose to target of 1.05 (>0.90). The dose rate at loading was 3.89 Gy per minute. None of the patients treated experienced severe complications. Conclusions The dosimetry studies are compliant with quality assurance standards for intracranial radiosurgery.