How proton therapy works

Proton therapy is an effective, accurate, and gentle cancer treatment method with minimal side effects. Thanks to the precise targeting of the proton beam directly to the tumor, the occurrence of side effects is significantly reduced. This gives proton therapy patients a chance to enjoy a quality life even after cancer treatment without an increased risk of late toxicity, which can appear several years after irradiation (10, 15, or even 20 years).

Although many people believe proton therapy is relatively new, it’s been around as early as 1946 with treatments on patients starting around 1954. Since then, proton therapy has evolved and expanded to many locations around the world, with the first UK proton centre for ocular tumours opening in 1989.

Based on worldwide experience and long-term results in treated patients, it is clear that patients after proton treatment have a higher quality of life compared to those who have undergone conventional (photon) radiotherapy.

 

The advantages of proton irradiation are based on physical laws and proton properties

The goal of modern oncological treatment is to ensure the maximum chance of recovery for patients while minimising adverse effects related to the treatment. Currently, this can be achieved by proton therapy. Unlike conventional radiotherapy, which uses photons for tumor cell irradiation and destruction, proton therapy is more advanced and uses protons. These particles give proton therapy its many advantages. Compared to conventional radiotherapy, the most significant advantage is its accuracy and ability to protect healthy tissues.

The commonly used photon beam goes through the body and emits a significant portion of its energy in the regions in front of and behind the tumor. Protons have a certain physical property called the Bragg peak, which means they emit significantly lower amounts of energy on their way to the tumor, thus minimising their impact on healthy tissues behind the tumor.

 

The most advanced form of proton therapy

Few patients are aware of the complexity of the technology hidden below the Proton Therapy Center, which ultimately allows us to treat cancer gently. Protons, the positively charged elementary nuclei of the hydrogen atom, are accelerated in the cyclotron to approximately half the speed of light. This provides them with energy to destroy tumours up to 30 centimetres deep. Then the protons are directed via a strong magnetic field into a very narrow beam and transferred to the tumour with high precision. As protons impact tumour tissue, they release energy, ionise, and damage the DNA of the affected cell. When the protons damage the tumour repeatedly, the cancer cells stop dividing or immediately die.

Pencil Beam Scanning (PBS) marks the exact distribution of the proton beam dose and is currently the absolute peak in proton therapy technology. PBS irradiates the target area with millimetre accuracy with minimal damage to surrounding healthy tissues and organs. With this irradiation method, the thin (pencil) beam is directed to the appropriate point of the target volume by means of a magnetic field. Highly precise control of this magnetic field achieves gradual irradiation of the entire tumor site.

To illustrate how PBS works, imagine the task of colouring in a circle on a piece of paper with a pencil. As you fill in the circle, you will focus on making sure that you do not cross the borders. PBS also focuses on staying within the boundaries of the area being treated. That is why side effects with proton therapy are minimal.