Dosimetric calculations and measurements of gold plaque ophthalmic irradiators using iridium-192 and iodine-125 seeds.

The dosimetry of ophthalmic plaques designed to hold iridium-192 or iodine-125 seeds is investigated experimentally and by means of a computer model. A phantom for thermoluminescent dosimetry (TLD) which permits measurements to within 2 mm of the plaque surface is described. TLD data are compared with model calculations that take into account the active length of the seeds, anisotropy of dose distribution from single seeds, and scatter within the phantom. An isotropic point source calculational model is accurate for clinical calculations, particularly at depths greater than 5 mm. Relative central axis dose measurements for 125I in a gold plaque are also in agreement with the model. Comparisons of 192Ir, 125I and 60Co plaques are presented. The relative advantages of using these isotopes in eye plaques are discussed.

Interstitial iodine-125 implant in the management of unresectable pancreatic carcinoma.

Eighteen patients with locally advanced adenocarcinoma of the head, body and tail of the pancreas were treated by a combination of biliary bypass, external and interstitial irradiation at Southern California Cancer Center of California Hospital Medical Center, Los Angeles, and Memorial Hospital Medical Center of Long Beach, Long Beach, CA, from July 31, 1975 to December 31, 1980. A dose of 3000 to 5000 rad was delivered to the pancreas and regional lymph nodes by external irradiation utilizing megavoltage units and 10,000 to 15,000 rad to the pancreas and metastatic lymph nodes by permanent Iodine-125 implants. In this group of 18 patients with unresectable carcinoma of the pancreas, excellent palliation of pain, jaundice and vomiting was achieved, with a median survival of 14 months.