About Proton Beam Therapy

What is proton therapy?



01 Proton therapy is a type of radiation therapy

The three main types of cancer treatment are:
surgery, chemotherapy, and radiation therapy.

Proton therapy is a type of radiation therapy which is recognized as an advanced medical treatment.
While traditional radiation therapies use photon rays such as X-rays and γ-rays, proton therapy uses a proton beam made by accelerating the nuclei of hydrogen atoms (protons) to increase their energy. Proton therapy has been attracting attention in recent years due to the fact that the physical properties of a proton beam allow for highly effective treatment with only mild physical side effects on the patient.



02 The proton beam can be directed at a tumor with pinpoint precision

In traditional radiation therapy, a radiation ray beam such as an X-ray beam releases its maximum energy dose close to the surface of the body and continues to release an energy dose which declines as it travels deeper into the body. As the beam continues beyond the tumor, depositing energy as it passes through the body, it unavoidably damages healthy tissue or organs behind the tumor.
By contrast, in proton therapy the physical properties of the proton beam allow it to release its maximum energy dose at a set depth inside the body and end there. Therefore, if the proton beam is adjusted to the depth of the tumor, the beam releases the maximum energy dose when it arrives at the tumor, and ends there without travelling any farther. By planning the optimal therapy for each individual patient, the proton beam can be used to effectively destroy the tumor with pinpoint accuracy while producing only a small effect on the surrounding healthy tissue.



The point where a proton beam releases its maximum energy dose is called the “Bragg peak.” In proton therapy, this Bragg peak is set to match the location and size of the tumor. Proton therapy is highly effective as it allows the energy dose released by an emitted beam to be more accurately concentrated on a tumor than is possible in traditional radiation therapy.

Illustrations of X-ray and proton beams inside the body

In traditional X-ray therapy, the beam goes past the tumor. It therefore delivers radiation not only to the tumor but also to other organs such as the heart and lung. In proton therapy, if the Bragg peak is set at the tumor, the beam ends there, therefore having less effect on healthy organs around the tumor.




03 Proton therapy has limited physical side effects and helps ensure a good quality of life

Proton therapy allows for cancer cells to be accurately targeted, causing much less damage to other healthy cells. In comparison with traditional radiation therapy, it produces milder side effects, resulting in only a small physical burden on the patient. The patient therefore has little trouble returning to his or her everyday life and maintaining a good quality of life. As a general rule, patients receiving proton therapy are treated as outpatients and do not need to be hospitalized.

The benefits of proton therapy

  • The proton beam can be delivered directly to the tumor with high amounts of energy and precision, resulting in highly effective treatment.
  • It can be accurately targeted at a tumor, minimizing the side effects on organs susceptible to the effects of radiation.
  • It can be used for the treatment of aged and frail patients due its reduced physical side effects.
  • The risks of secondary cancer in children or young people are low.
  • It can also be used to treat cancer patients who have complications and are unable to undergo surgery.
  • Patients can visit the hospital for daily treatment as outpatients and do not need to be hospitalized.
  • Patients are likely to have less difficulty returning to daily life in society, and can maintain a good quality of life.

Side effects of proton therapy

While proton therapy minimizes the effects on healthy tissues and organs and therefore causes relatively fewer physical side effects than traditional radiation therapy, it may produce some side effects. For example, in some cases patients develop sunburn-like symptoms on the skin of the part of the body which the proton beams were directed at. The side effects of proton therapy may differ according to the part of the body in which the tumor is located and the angle of the proton beam. A specialist will explain such side effects in detail if you are considering receiving proton therapy, and it is important to ensure that you understand the possible side effects before deciding to proceed with the therapy.