Development of simple proton system with novel correction methods of proton scattering
Development of simple proton system with novel correction methods of proton scattering
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采用新颖的质子散射校正方法开发简单的质子系统
DOI：
10.1016/j.nima.2018.05.034
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T. Inaniwa
中科院分区：
文献类型：
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作者：
M. Takabe;T. Masuda;M. Arimoto;J. Kataoka;K. Sueoka;T. Maruhashi;S. Tanaka;T. Nishio;T. Toshito;M. Kimura;T. Inaniwa
为了安全有效的质子治疗，患者体内的质子范围由水当量长度（WEL）表征，并且必须准确地确定。目前的治疗计划是基于X射线计算机断层扫描图像，这可能会导致不确定性，因为不同的质子和X射线之间的能量损失过程。我们开发了一个简单，新颖，实时质子CT系统。该系统使用CCD摄像机和闪烁体，闪烁体足够薄，质子可以穿透。由于质子在穿过体模时损失能量，因此在闪烁体中采集对应于质子能量损失的不同发射。闪烁体的图像由CCD照相机用70 MeV和200 MeV质子束收集。由于模糊由于质子反应，如多次库仑散射和核反应显着降低在两个光束中获得的图像，我们开发了两种有效的校正方法。一种方法应用于宽波束系统，而另一种方法应用于窄波束系统。我们成功地获得了清晰的图像与轻微的质子反应的影响，通过应用这些校正方法。此外，我们确认，从所获得的CT图像估计的WEL值与聚甲基丙烯酸甲酯（PMMA）和异丙醇等材料的理论值一致，在1-σ的不确定性。通过模拟，我们发现，核反应显着贡献的WEL值的不确定性。
For safe and effective proton therapy, the proton range in a patient’s body is characterized by the water equivalent length (WEL), and must be accurately determined. Current treatment planning is based on X-ray computed tomography images, which might cause uncertainty because of the different energy loss processes between protons and X-rays. We develop a simple, novel, and real-time proton CT system. The system uses a CCD camera and scintillator, which is thin enough for protons to penetrate. Since protons lose energy when they pass through a phantom, different emissions corresponding to the proton energy loss are acquired in the scintillator. Images of the scintillator were gathered by the CCD camera with 70 MeV and 200 MeV proton beams. Since blurring due to proton reactions such as multiple Coulomb scattering and nuclear reactions significantly degrades the obtained images in both beams, we developed two kinds of effective correction methods. One method is applied to broad beam systems, while the other is applied to narrow beam systems. We successfully obtain clear images with minor proton reaction effects by applying these correction methods. Moreover, we confirm that the WEL values estimated from the acquired CT images agree well with the theoretical values for materials such as polymethyl methacrylate (PMMA) and isopropyl alcohol, within 1-σ uncertainty. Through simulations, we found that nuclear reactions significantly contribute to the uncertainty of WEL values.