Advancing proton beam therapy treatment

Proton beam therapy (PBT), a type of radiotherapy which administers a dose of high energy protons precisely targeted at a tumour, is enhancing patient care, quality of life and longevity thanks to a high level of precision. In this article, Hitachi’s Ken Umei discusses how the technology has developed and the ways the treatment is improving patient outcomes.

Doctors have been striving for new ways to treat cancer since the days of Hippocrates – the father of medicine coined the terms “carcinos” and “carcinoma” to describe non- ulcer forming and ulcer-forming tumours. Since then, huge leaps have been made in treatment. Radiation, chemotherapy and surgery have contributed to far better survival rates for many forms of cancer. However, these treatments have limitations for patients suffering from certain forms of cancer. For example, with conventional radiation, there is the challenge of collateral damage to surrounding organs and tissue as the x-rays travel through the body in a straight line without stopping. For certain groups of patients, or where the cancer is close to a critical part of the body, such as the spinal cord, conventional treatment is not the best option.

The answer? A more precise form of treatment that can target the tumour without affecting the surrounding health cells and tissue.

The dawn of proton beam therapy Proton beam therapy (PBT) is an advanced type of cancer radiotherapy which directs a beam of protons (hydrogen nuclei) or carbon ions at an accelerated speed of up to 70% the speed of light to destroy and eradicate cancerous cells, while reducing damage to surrounding healthy tissue and vital organs. As well as benefitting a vast number of cancer patients, the accuracy of the therapy provides a particular advantage to patients where the cancer is close to a critical part of the body, such as the spinal cord or brain. However, it should be noted that PBT is only suitable for certain types of cancer, such as highly complex brain, head and neck cancers

and sarcomas, as it does not lead to better outcomes for many cancer cases than using high energy x-rays.

The potential for treating patients with protons was realised as long ago as 1946 by physicist Robert R. Wilson, who discovered the potential use of the proton to target tumours. The first attempts to translate this potential into practice were carried out in physics laboratories that could accelerate the protons to a high enough energy. As technology progressed and the benefits of PBT became clearer, the first hospital based high energy proton facility exclusively for patients was introduced at Loma Linda in California in 1990. Since then, interest from manufacturers and clinical oncologists has seen an exponential growth in the treatment.

The benefits of proton beam therapy

Along with improving success rates, there is increasing demand for better quality of life, so that patients can continue to function in society while receiving treatment. This is why PBT is considered by many to be one of the most advanced cancer treatments available. For example, in contrast to conventional radiation therapy, which is based on photons, PBT delivers the majority of its energy within a small range inside the tumour, known as the Bragg peak, reducing adverse effects to adjacent healthy tissues. According to the American Society of Clinical Oncology (ASCO), proton therapy may deliver up to 60% less radiation to healthy tissue around the target site, while delivering a higher dose to the tumour itself.1 What’s more, in standard radiation therapy, the x-ray beams deposit energy along their path before hitting their target, for example, on the body’s surface and beyond. The x-ray beam continues beyond the tumour,


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