Medical 6 MeV linear accelerator made in Japan.

A 6 MeV medical linear accelerator manufactured by the Mitsubishi Heavy Industries, Ltd., has been installed in the Aichi Cancer Center Hospital. This is the first unit of this type made in Japan. This paper giv'es a brief description of the unit, reports the results of a series 'of tests for radiation and mechanical accuracy, and summarizes the one year history of calibration and stability. One of the most striking characteristic is a mechanism that deflects the electron beam, coming out of the acceleration tube at 180 degrees and using two steps deflection magnet system. The maximum X-ray output was 465 R/min at one meter from the target with the actual maximum energy of 5.75 MeV. The unit was used for clinical radiotherapy for the past year, and treatment was only interrupted one day because of mechanical trouble.