A Study of Computer Tomography with Accelerated Proton Beam

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A proton computer tomography (CT) has been proposed and investigated. A 12UD tandem accelerator is used to accelerate proton particles. The energy of the proton is 24MeV.Though the principal of the proton CT is similar to that of a X-ray CT,a new idea is requested to realize it because the interaction mechanism of the proton in the material strongly different from that of the X-ray. A new idea, which is named Residual Energy Method, is proposed and is gotten a tryout. According to the idea, a tomogram is made from the electronic stopping power of the proton at the each part of an absorption material. As comparison with the X-ray CT,we can expect several advantages in the proton CT.Here, the strong points are summarized. 1) A very high quality tomogram can be get with less proton irradiation to a person because of measurement of all proton particles which are irradiated. Then, it is expected the decrease of a specific dose of radioactivity. 2) In contradiction to the X-ray, the proton particle can be focused on a very small portion of the irradiated material with several kind of electromagnetic optical devices because it is charged particle, not electrostatic wave like X-ray. Consequently, it becomes easier to get the tomogram with very high specific resolution.The proton CT has been tried with a haunt. The diameter of the proton beam is controlled to be less than 0.1mm. The tomogram has been observed successfully. The space resolution is 0.25mm which is sufficient for medical usage. The trials are still under investigation.