RADIO-OPAQUE MARKERS FOR STEROTACTIC IMAGING OF UVEAL MELANOMA

In in vitro and in vivo studies, episclerally sutured radio-opaque mar kers were evaluated as localizers for better determination of the clin ical tumour volume prior to stereotactic radiotherapy of uveal melanom a. Four different types of markers were studied in vitro: tantalum mar ker, 2.5 mm in diameter; ring-shaped markers custom-designed in polyme thyl methacrylate (PMMA), 2.6 mm and 3.0 mm in diameter; and barium-im pregnated silicone rubber spheres, 2 mm in diameter, in vivo PMMA mark ers 3.0 mm in diameter and barium-impregnated silicone rubber spheres 2 mm in diameter were used. The best results were obtained with the ba rium-impregnated silicone rubber spheres both in vitro and in vivo. Fo r the CT-delineation of selected uveal melanomas with either a flat di scoid shape or flat tumour extensions or when adjacent serous retinal detachment is present, small episclerally sutured barium-impregnated s ilicone rubber spheres are useful as localizers for determining, the c linical tumour volume.