Proton beam irradiation for ocular melanoma, 2

Seventy MeV Proton beam irradiation (beam range:38 mm in the water) was applied for the treatment of 6 patients of ocular melanoma between October 1985 and July 1986 at National Institute of Radiological Sciences(NIRS). The Proton beam has more localized and uniform dose distributions than the electron beams, leading to increased delivery of the dose to tumors with out excess exposure to adjacent normal tissues. Since the accurate treatment planning was necessary for the Proton beam therapy, various studies concerned with the diagnosis of tumor localization using X-CT, MRI or ultrasonography and with the methods for fixation of the body or target using holder or plastic shell were performed. The diagnosis of ocular melanoma was established in the all cases through clinical examinations, such as indirect ophthalmoscopy, fundus photography, fluorescein angiography, ultrasonography and so on. The narrow horizontal Proton beam(10 ∼ 24 mm diameter) was straightly irradiated to the tumor, through the several thicked bolus, avoiding an exposure to the lens. The dose of 30 ∼ 60 Gy/3 ∼ 5 fractions/3 ∼ 5 weeks (TDF 90 ∼ 150) was prescribed. Although the follow up studies in order to estimate the tumor response and the complications are not enough to long to evaluate the results, we believe that Proton beam irradiation is considered to be an excellent therapy for the management of ocular melanomas, alternative to enucleation of affected eye. (author)