A medical charged-particle radiation therapy system is a device that produces by acceleration high energy charged particles (e.g., electrons and protons) intended for use in radiation therapy. This generic type of device may include signal analysis and display equipment, patient and equipment supports, treatment planning computer programs, component parts, and accessories.

The 120 Leaf MLC is indicated for use with the Mitsubishi EXL series linear accelerators to ) provide the ability to adjust the field shape to conform to tumor shapes. It can be a ) substitute for conventional customer blocks. 6. ison of logi istics: This submission describes the modification of existing MLC by increasing the number of leaves. Positions of leaves in both types of MLC are adjusted by motor drive mechanisms using computerized controllers. f e DEPARTMENT OF HEALTH & HUMAN SERVICES Public Health Service mr. Food and Drug Administration 9200 Corporate Boulevard JAN A 1998 Rockville MO 20850 Mitsubishi Electronics America, Inc. Re: K973963 c/o C. L. McIntosh & Associates Mitsubishi 120 Leaf Multileaf Collimator (MLC) 12300 Twinbrook Parkway, Suite 625 . for EXL Accelerator Series Rockville, MD 20852 Dated: October 14, 1997 Attn: T. Whit Athey Received: October 16, 1997 Regulatory class: II 21 CFR 892.5050/Procode: 90 IYE Dear Mr. Athey: We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is