The National Institute of Radiological Sciences has investigated multiple-ion therapy using energetic beams of helium, carbon, oxygen, and neon ions, to improve treatment outcomes of refractory cancer. For this therapy, it is necessary to ensure the helium-ion beam purity to avoid irradiation by unwanted ions. Here, we develop a measurement method for monitoring beam purity. This method can measure the charge number of the ions in a high-purity beam using an ionization chamber and Faraday cup. In addition, it can be used to detect the contamination of the clinical helium-ion beam. We perform beam experiments to evaluate our beam-purity monitoring method and predict that our method is capable of detecting contamination below 1%.

中文翻译：

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重离子放疗多离子束手术临床束流纯度监测系统的实验研究

美国国家放射科学研究所已经研究了使用氦、碳、氧和氖离子的高能束的多离子治疗，以改善难治性癌症的治疗结果。对于这种疗法，必须确保氦离子束的纯度，以避免被不需要的离子照射。在这里，我们开发了一种用于监测光束纯度的测量方法。这种方法可以使用电离室和法拉第杯测量高纯度光束中离子的电荷数。此外，它还可以用于检测临床氦离子束的污染。我们进行光束实验来评估我们的光束纯度监测方法，并预测我们的方法能够检测到低于 1% 的污染。