INTRACAVITARY IRRADIATION OF THE BLADDER WITH RADIOACTIVE BETA-EMITTING RUBBER BALLOON CATHETERS.

Abstract

Many technics (1, 2) utilized for the treatment of bladder papillomatosis are subject to the same drawback summarized by Meyer Melicow: “Many recurrences have been present as preneoplastic lesions or as microscopic tumors invisible to the naked eye at a previous operation but which come of age at a later date” (3). Gamma radiation in particular causes severe bladder muscle fibrosis and consequent loss of the muscular capacity. In intracavitary irradiation with radium (4–6) or cobalt (7) it is difficult to properly center the charge (8, 9). Walton and Sinclair, by using a plastic bag containing radioactive isotopes in solution (10, 11), have solved some of these problems. Direct injection of a colloidal solution into the bladder cavity itself as suggested by Muller has been carried out. The potential hazards to personnel exposed to voided radioactive colloidal gold have been mentioned (12, 13), and notable contributions to dosage calculations have been made (10,14). The chief problems in mind when we undertook this study were: 1. (a) All these isotopes are primarily gamma emitters and hence have a depth of penetration which includes the muscularis. For application to superficial (I, II, A) papilloma, this is not desirable. 2. (b) There is a possibility of unevenness of radiation in some instances, or elaborate procedures are required to obtain uniformity. 3. (c) Contamination of the bladder, the urine, and personnel in the area may occur. We wished to obtain an admittedly imperfect, but possibly improved control of papillomatosis in the early stage by which we could hope to offer our patients a better chance for preservation of bladder function. It was thought that more extensive observations should be made concerning beta radiation. Consequently, a fairly elaborate program was devised for preparation of the balloons, the measurement of dose, and biopsy of the irradiated dog bladder. It was believed that if a source of beta radiation could be impregnated in the balloon of a Foley catheter, irradiation of the bladder uniformly by the urethral route would be possible. Furthermore, if the desired depth of penetration into tissue were obtained, damage to the muscularis would be prevented. Contamination of the bladder would be avoided by firmly embedding the isotope in the rubber of the balloon. If these conditions could be met, an additional technic for the treatment of papilloma of the bladder would be available, by which in suitable cases the difficulties encountered in intracavitary methods of irradiating the bladder would be minimized and an alternative to surgical treatment of these superficial, noninfiltrating neoplasms would be offered. Selection of a Suitable Isotope: Silver III The theoretical desired dosage was taken as 3,000–4,000 rads, confined to the mucosa area at a depth of 1–2 mm.