ABSTRACT
Monte Carlo calculations of radiation dosimetry using MORSE code are performed for 125I and 60Co point sources in a cylindrical head phantom that simulates the geometry of eye plaque therapy for choroidal melanoma. We obtain the dose variation in the eye at submillimeter intervals over distances as close as 1 mm and up to 2.5 cm from the source. The calculations for 125I are performed for the phantom media of water, protein, and a homogenized protein-water mixture simulating the composition of the eye. Relative dose functions for 125I for these phantom media are fitted to second-degree polynomials. Agreement is found with published results. The relative dose function for 60Co at eye position in the water head phantom is fitted to a third-degree polynomial and compared with that for 60Co at the center of a large water sphere. A boundary effect due to the head phantom-air interface on the dose distribution for 60Co is demonstrated. The dose falloff with distance is faster for the eye geometry compared with the bulk geometry. We also show that the relative dose distributions within the tumor are comparable for 125I and 60Co by comparing their relative dose functions. This result is consistent with the success of clinical trials of large melanoma treatments with 125I plaques.
Subject(s)
Choroid Neoplasms/radiotherapy , Melanoma/radiotherapy , Radiotherapy Dosage , Biophysical Phenomena , Biophysics , Cobalt Radioisotopes , Humans , Iodine Radioisotopes , Models, Anatomic , Monte Carlo MethodSubject(s)
Neoplasms/therapy , Patient Care Team , Referral and Consultation , Breast Neoplasms/therapy , Carcinoma, Small Cell/therapy , Colonic Neoplasms/therapy , Combined Modality Therapy , Female , Hodgkin Disease/therapy , Hospitals, Community , Humans , Lung Neoplasms/therapy , Male , Ovarian Neoplasms/therapy , Prognosis , Prostatic Neoplasms/therapy , Rectal Neoplasms/therapy , Testicular Neoplasms/therapyABSTRACT
Increase in splenic uptake of Tc-99m sulfur colloid was noted in 47 of 147 (32%) patients with cutaneous malignant melanoma early in the coure of disease. Patients with disseminated disease and/or clinical or laboratory evidence of hapatic dysfunction were excluded from study. Recurrence rate of 2 yr was higher for those patients with splenic scans demonstrating augmented uptake compared with patients having normal scans, 36% against 16% (p less than 0.02). These differences resulted from a much more favorable prognosis in women with normal scans contrasted with women with increased uptake, 6% against 26% (p less than 0.05). Women with increased splenic uptake, and all men regardless of scan status, seemed to have a higher rate of recurrence than women with normal spleen scans. Scan status may be an adjunctive prognostic marker in women.