| Paper | Title | Page |
|---|---|---|
| TUPSA31 | Magnetic System of Isochronous Cyclotron F250 for Proton Therapy Applications | 103 |
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| In the Laboratory of Nuclear Problems of the JINR the possibility of designing of the isochronous cyclotron F250 with the energy of protons 250 MeV on the basis of magnet with the diameter of pole 6 m, which is used for the synchro-cyclotron is examined. Synchro-cyclotron many years works for obtaining the protons with the energy 680 MeV and with the intensity of extracted beam 2.5 mkA. For the solution of medical problems the required energy of protons comprises not more than 250 MeV and depends on the depth of the tumor arrangement inside a patient. For determining the required energy of protons the information about the mean free path of protons in the correspondence for the position of Bragg's peak in each case is used. Necessary energy of protons is obtained by means of degrader system providing a retarding the extracted beam of protons with 680 MeV to 250 MeV and less. In this case the utilized for medical purposes intensity of beam does not exceed 50 nA. The proposed cyclotron F250 will make it possible to strongly decrease the electric power of magnet and to avoid the need of beam degradation from 680 MeV to 250 MeV. For creating the required magnetic field of the cyclotron F250 it is necessary to change the form of steel spiral shims and disks, located inside a vacuum chamber of synchro-cyclotron. The basic parameters of the magnetic system of the cyclotron F250 with the condition of retaining the vacuum chamber and the magnet yoke of synchro-cyclotron are given. | ||