According to the remarkable progress of high energy medical radioation apparatuses, the part of the teletheraphy using linear accelerator and telecobalt is now occupying almost the whole portion of cancer therapy in the field of radiation treatment. However, even in the present days, inserting sealed small source theraphy applied interstitially and intracavitry shows better results in some kinds of tumors just as the tumors of the tongue and those of the uterine cervix, especially, high dose rate sources are more effective for it. On the technic of these inserting theraphy, the dose calculations in the tumor are the most troublesome procedures to determine the therapy technic, and its technic must be doing under accurate dose distribution, dosimetry and localization. The high dose rate remotely controlled after loading apparatus, Toshibal RAL 303 , was installed in Yonsei Cancer Center in 1979. We applicated the computer technique to the dose computation and enabled to improve the accuracy of intracavitary irradiation for the cervix cancer. To obtain the exact localization of applications in the uterine cervix. We fabricated the simulating scaler and metallic o-ring contacting in tandem. Optimum standard arrangements of radiation sources were confirmed as 10 types, according to statistical evaluation of patients who had received brachtheraphy.