Energy of proton accelerator necessary for treatment of choroidal melanomas

We have reviewed 94 patients with choroidal melanoma treated by proton beam therapy at the Harvard Cyclotron Laboratory. A beam penetration of f27 mm would be required to treat 90% of the lesions. We conclude that a machine energy of at least 55 and, preferably, 60 MeV would be necessary for a clinically viable therapy unit for the treatment of choroidal melanomas. An extracted beam current of 10(-9) A would be more than sufficient.