Radiotherapy of bile duct carcinoma using intracatheter 198Au grains

Eight patients with bile duct carcinoma were treated with radiotherapy using intracatheter 198Au grains. The intracatheter 198Au grains in an inner tube were inserted into a percutaneous transhepatic catheter. A plastic tip was placed between these grains to improve spatial and temporal dose allocation. This method and 192Ir wire irradiation resemble each other closely in dose distribution, but the former has the following advantages over the latter. 1) The number of 198Au grains used can be changed quite easily in accordance with the length of the stenosis. 2) The half-life of 198Au is about 2.7 days, and a dose of 25-40 Gy at 1.0 cm from the source is delivered over this period. The medical staff can protect themselves from radioactivity when the sources are withdrawn after brachytherapy. 3) 192Ir wire is not used very frequently in spite of its long half-life (74 days) because bile duct carcinoma is uncommon. 4) In Japan, 198Au grains can be purchased on a weekly basis, so treatment plans can be easily made. The eight patients also received external irradiation and the median survival after onset of radiotherapy was 7.9 months. There have been few systemic or local complications.