[Status and developmental prospects of the medical proton channel in the synchrocyclotron in Gatchina].

The medical proton beam on the synchrocyclotron in Gatchina modernized in 1980, is characterized by a simplicity of the beam adjustment that amounts to standard operations, the time of adjustment reduced considerably. The optical scheme ensures a good reproducibility of all the beam parameters from session to session. A large "zone of convergence" makes it possible to select a necessary irradiation field size with the diameter from 3 to 10 mm. A new medical complex with a 2-room premises for irradiation is envisaged on the basis of the "second beam" to expand the medical program. The piercing technique of moving field irradiation with protons at an energy of 1 Gy and the utilization of the convergent beam ensure the ratio of the focal dose to the surface dose 200:1.