A modular, integrated electron gun and RF cavity for radiotherapy treatment systems in developing countries

在英国，每10名癌症患者中就有4人在基于直线电子加速器(LINAC)的放射治疗(RTT)系统上接受放射治疗。在非洲收入最低的国家，需要放射治疗的癌症患者中只有4%接受了RTT。目前，在这片拥有54个国家和10亿人口的大陆上，有385台放射治疗机。大约60%的机器仅在三个国家找到：南非、埃及和摩洛哥。接下来的20%也只分布在三个国家：突尼斯、尼日利亚和阿尔及利亚。图1显示了每百万人拥有RTT机器的数量，正如在欧洲可以看到的那样，几乎所有国家每20万人拥有一台以上的机器，而在非洲，许多国家每500万人拥有的机器不到一台。尽管这些机器的高成本是一个问题，但停机时间是非洲放射治疗中心的一个主要问题，这可能会影响治疗结果，并严重限制RTT设施的数量。2016年，加纳唯一的RTT出现故障，自1995年以来一直在运行，而大多数RTT机器在制造商进行适当维护的情况下只能使用10-15年。在这个项目中，我们的目标是优化放射治疗系统，使维护更容易，同时延长RTT系统的寿命。最常见的故障部件之一是直线加速器的电子源(枪)，它的寿命可达2-3年。通常，电子枪是直线加速器的一个组成部分，如果出现故障，所有的直线加速器都需要更换或退回制造商进行维修，这很昂贵，而且需要很长时间。我们的目标是制造一种可以从直线加速器上单独维修的模块化电子枪。我们还将考虑降低射频腔的成本，并将腔内的光束损失降至最低，以帮助降低成本。

4 in 10 patients with cancer in the UK receive radiotherapy treatment on a linear electron accelerator (linac) based radiotherapy treatment (RTT) system. In the lowest income counties within Africa only 4% of cancer patients that need radiotherapy receive RTT . There are currently 385 radiotherapy machines on the continent of 54 countries and 1 billion people. About 60% of the machines are found in just three countries: South Africa, Egypt and Morocco. The next 20% are also in just three countries: Tunisia, Nigeria and Algeria. Figure 1 shows the number of RTT machines per million people , as can be seen in Europe almost all counties have more than 1 machine for every 0.2 million people while in Africa many countries have less than 1 machine per 5 million people. Even though high cost of these machines is an issue, downtime is a major issue in African radiotherapy centres which can affect treatment outcomes and severely limits the number of RTT facilities. In 2016 Ghana's only RTT failed, having been in operation since 1995, while most RTT machines are only meant to last 10-15 years with proper maintenance by the manufacturer. In this project we aim to optimise a radiotherapy system to make maintenance easier while extending the life of an RTT system. One of the most common parts to fail is the electron source (gun) of the linear accelerator which can have a lifetime of 2-3 years . Typically, the electron gun is an integrated part of the linac, and in case of fault all of the linac needs to be replaced or returned to the manufacturer for repair which is expensive and takes a long time. Our aim is to make a modular electron gun that can be repaired seperately from the linear accelerator. We will also look at reducing the cost of the RF cavity and minimising beam losses inside the cavity to help reduce the cost as well.