How does proton therapy work?

Proton therapy is an innovative radiation technique that can be used to treat certain malignant cancer cells or tumours, with the advantage that the radiation dose on healthy tissue is relatively small while the radiation dose on the tumour itself remains the same.

Classic radiotherapy: photons

Classic radiotherapy uses photon beams. These are packets of electromagnetic radiation, like visible light or radio waves, but with a much higher energy. The radiation dose delivered by a photon beam gradually decreases as it penetrates deeper into the body.

As a result, a limited amount of radiation dose also reaches the healthy tissue located in front of and behind the tumour. Depending on the sensitivity of these tissues and the exposure, side effects may occur.

However, thanks to major advances in radiation techniques in recent years, the treatment has been increasingly refined and can be administered more precisely.

Proton therapy: protons

Proton therapy uses a beam of protons. These are positively charged particles originating from the nucleus of an atom, which only release their maximum radiation dose when they reach a certain depth in the body, at which point the radiation stops completely (unlike photons).

This radiation dose peak is called the Bragg peak. The depth of the peak can be determined by adjusting the energy of the proton beam. The higher the energy of the beam, the deeper the Bragg peak is located in the body. Furthermore, the proton beam can also target a specific part of the tissue by using bending magnets in the device. To get a homogeneous dose in the tumour, a large number of fine proton beams with different energies and positions are combined in rapid succession. Thus, the tumour is "coloured" with radiation dose. This technique is called pencil beam scanning.

Both photon therapy (classic radiotherapy) and proton therapy use multiple beams from different directions, with the aim of delivering as little radiation as possible to the surrounding healthy tissue.

Last edit: 17 February 2023