A Study of Computer Tomography with Accelerated Proton Beam

提出并研究了一种质子计算机断层成像（CT）。12UD串列加速器用于加速质子粒子。质子的能量为24MeV，虽然质子CT的原理与X射线CT相似，但由于质子在材料中的相互作用机制与X射线CT有很大的不同，因此质子CT的实现需要一种新的思路。本文提出了一种新的思路，即剩余能量法，并进行了尝试.根据这个想法，断层图像是由质子在吸收材料的每个部分的电子阻止能力制成的。与X射线CT相比，质子CT具有许多优点，本文对其优点进行了总结。1)由于测量了被照射的所有质子粒子，因此可以在对人的较少质子照射的情况下获得非常高质量的断层图像。然后，预期放射性的特定剂量降低。2)与X射线不同的是，质子粒子是带电粒子，而不是像X射线那样的静电波，因此可以用几种电磁光学器件聚焦在被照射材料的很小一部分上。质子CT在临床应用中遇到了一些问题，如图像质量差、分辨率低等。质子束的直径控制在0.1mm以下。断层图像已成功观察。空间分辨率为0.25mm，足以满足医疗用途。审判仍在调查中。

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.