Comparison of the cost between 60Co and 192Ir, as the sources for high-dose-rate remote control afterloading systems (HDR-RALS)

High-Dose-Rate remote control afterloading systems (HDR-RALS) installing 60Co sources have been prevailing currently in Japan. The survey conducted by Japan Isotope Association (JIA) reports that 180 machines are at working condition. Although the wide prevalence of the HDR-RALS, the stable supply of 60Co is becoming difficult because of the short availability of raw materials. The supply of 60Co is planned to be terminated in March 1996. In place of 60Co, 192Ir is going to be produced in 1996. The size of 192Ir, which is much smaller than that of 60Co, may facilitate broader clinical usability. On the other hand, for the reason that the half life of 192Ir (73.8 days) is much shorter than that of 60Co (5.27 years), several exchanges of the sources in a year are necessary. This report analyses the difference of the cost between 60Co and 192Ir as the sources for HDR-RALS. As the cost of the 60Co sources is dependent on the distance from Tokyo. Radiation activity, etc., the cost-calculation was done on the basis the 60Co sources were installed for the HDR-RALS systems in Yamanashi Central Hospital. The total cost of 60Co is 3,377,000 yen on the data from JIA. According to the half life of 5.27 years, the available duration can be thought as 7 years and the monthly cost be calculated as about 40,000 yen. In case of 192Ir, the prices for Buchler' system and Nucletron's system are 800,000 yen and 990,000 yen respectively. Concerning the shortness of the half life, an exchange in every 3 months is ideal. Therefore the monthly cost of 192Ir would be 260,000-330,000 yen. Consequently the cost-ratio for 192Ir and 60Co would become 6.7-8.3. The cost of intracavitary irradiation is controlled by the government as 10,000 yen per treatment in Japan. If this setting remains the same for HDR-RALS installing 192Ir, almost all the facilities of radiation therapy would suffer from the cost-income inbalance in the near future. (author)