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人接受基于线性电子加速器（linac）的放射治疗（RTT）系统的放射治疗。在非洲收入最低的国家，需要放疗的癌症患者中只有4%接受了RTT治疗。目前在54个国家和10亿人口的非洲大陆上有385台放疗机。大约60%的机器分布在三个国家：南非、埃及和摩洛哥。接下来的20%也集中在三个国家：突尼斯、尼日利亚和阿尔及利亚。图1显示了每百万人中RTT机器的数量，可以看到，在欧洲，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500万人拥有不到一台机器。尽管这些机器的高成本是一个问题，但在非洲放射治疗中心停机是一个主要问题，这可能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发生故障，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疗系统，使维护更容易，同时延长RTT系统的寿命。直线加速器的电子源（枪）是最常见的故障部件之一，其使用寿命可达2-3年。通常情况下，电子枪是直线加速器的一个组成部分，一旦出现故障，所有直线加速器都需要更换或返回制造商进行维修，这是昂贵的，需要很长时间。我们的目标是制造一种模块化的电子枪，可以与直线加速器分开维修。我们还将着眼于降低射频腔的成本，并最大限度地减少腔内的波束损耗，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.