Since there are many fashions of cobalt 60 teletherapy units, linear accelerators and betatrons available at present, we studied about the way of selection of high energy radiotherapy units for deep therapy, from a stand point of management and control based on our past measurments. Cobalt 60 teletherapy unit equiped with a source of 1500 Ci assigns us a little labor for management and control and it has a high commutability of physical data each other, but the number of patients being treated is not great (about 30 patients a day). Linear accelerator can treat more (about 75 patients a day), but assigns us a great labor for management and control. So, the way to select cobalt 60 teletherapy unit or linear accelerator should be decided from a balance between the number of patients and the labor for management and control. Output dose of betatron x-ray is less and stability of it is lower than other high energy teletherapy units for deep therapy. We should deem it is used as an exclusive unit for electron beam therapy only.
