Proton Beam Therapy

A non-invasive cancer treatment "without the need for surgery"

Conventionally, cancer is treated by surgery, by chemotherapy using anticancer drugs, or by radiation therapy. Because radiation therapy places less burden on the body, it is also suitable for elderly patients or those who are judged unable to be cured by surgery.

While conventional radiation therapy uses photons (X-rays or gamma rays), the newer "particle beam therapy" uses protons or carbon ions (heavy particles).

Proton beam therapy can be finely adjusted according to the size and depth of the lesion so as to avoid normal tissue and precisely irradiate the cancer. It causes fewer side effects than conventional radiation therapy, and by concentrating a large radiation dose on the tumour the treatment time is shorter. For cancers that are currently difficult to treat, proton beam therapy has shown more remarkable results.

Principles of Proton Beam Therapy    

Particle beams include neutron beams, proton beams, carbon ion beams (heavy particle beams) and electron beams. Of these, proton beams and carbon ion beams (heavy particle beams) are commonly used in cancer treatment.

Proton beam therapy works by using a large device called a "synchrotron" to strip electrons from hydrogen atoms and accelerate the resulting protons in a vacuum to about 70% of the speed of light in one go, producing a proton beam with strong penetrating power that can destroy cancer cells in the body.

Advantages and Features of Proton Beam Therapy    

Thanks to its physical and biological characteristics, proton beam therapy enables non-invasive treatment with fast post-treatment recovery.
Compared with surgery, drug therapy and conventional radiotherapy, it places less burden on the patient's body and carries a lower risk of side effects, and is recognised as an effective means of treating cancer.

Comparison of Proton Beam Therapy with Conventional Radiotherapy (X-rays)     

When conventional radiation such as X-rays is directed at the human body, the energy released is highest near the skin and gradually decreases as it enters the body. When treating a deep-seated tumour, side effects on normal tissue are greater.

Conversely, proton beam therapy releases a relatively small radiation dose near the skin, releases high energy only when it reaches a specific tumour inside the body, and decays and disappears immediately after passing the tumour's depth. This characteristic of proton beams is named the "Bragg peak" after its discoverer.

By adjusting the Bragg peak with specialised mechanical devices according to the shape and depth of the tumour, energy can be concentrated on the tumour while reducing side effects on normal tissue, maximising patient benefit.

Indications and Non-indications for Proton Beams / Approximate Number of Treatments and Duration   

  Tumours in the sites shown in the diagram above can generally be considered for proton therapy, but they must be localised tumours, i.e. tumours with no spread or metastasis.
Non-indicated conditions.

⚫ Cancer cells found to have metastasised to multiple sites
⚫ Previous radiation therapy
⚫ Cancers of the gastrointestinal tract

Proton beam therapy is given once a day, 3–5 times a week, generally totalling about 10–39 sessions over the whole course, decided according to the actual condition and treatment plan. Its advantage is fewer sessions than conventional radiotherapy. One treatment session, including positioning, takes about 15–30 minutes, with actual irradiation lasting 1–3 minutes.

Heavy Ion (Heavy Particle) Beam Therapy

What Is Heavy Ion Beam Therapy? "Heavy ion beam" = carbon ion beam
In a broad sense, "heavy ion beam" refers to all particle beams heavier than electrons; in Japanese heavy ion medicine it refers to beams of atomic nuclei (heavy ions) of atoms with an atomic number heavier than helium (He). Japan has used carbon ion beams, one type of heavy ion beam, for cancer treatment for nearly 20 years, and the "heavy ion beam" used in cancer treatment refers to the "carbon ion beam". In cancer treatment, carbon nuclei 12 times heavier than protons are accelerated to about 70% of the speed of light for irradiation.

Principles of Heavy Ion (Heavy Particle) Beam Therapy

Among radiation, those heavier than electrons are called particle beams, and those heavier than helium ion beams are heavy ion beams. Heavy ion beam therapy uses this heavy ion radiation for treatment, in particular carbon ions.
Particle beam therapy is radiotherapy using heavy ion (carbon ion) beams, mainly applied to cancer treatment.

Functions of Heavy Ion (Heavy Particle) Beam Therapy

Heavy ion radiation (carbon particles) is accelerated to about 70% of the speed of light and irradiated, strongly destroying deep cancer lesions inside the body.
Cancer lesions inside the body can be treated without a scalpel and without pain.

Comparison of Heavy Ion (Heavy Particle) Beam Therapy with Conventional Radiotherapy

In heavy ion beam therapy, heavy ion (carbon ion) beams are accelerated to about 70% of the speed of light and irradiated to attack deep cancer lesions in the body. With conventional X-ray radiotherapy, the deeper it enters the body the weaker its influence (destructive strength) becomes, whereas heavy ion beam therapy can set a peak for its influence (destructive strength) inside the body, allowing effective irradiation aimed at the cancer lesion.

Particle Beam TherapyConcentrated irradiation according to the shape and depth of the cancer lesion. A dedicated tool (collimator) that adjusts the irradiation to the shape of the cancer lesion
and a compensating filter make this possible. Individualised irradiation treatment is given to each patient, reducing the impact on important organs such as the spinal cord.

Reducing the impact on surrounding important organs and the spinal cord while treating the cancer

Three Major Features of Heavy Ion (Heavy Particle) Beam Therapy

① Concentrated irradiation of the cancer lesion

A therapy that concentrates destruction on the cancer lesion with little destruction of surrounding normal areas. It causes fewer side effects than general radiotherapy.

② Effective even for cancers that respond poorly to general radiation

It has a stronger biological effect than general X-rays. For example, it is effective for osteosarcoma, which responds poorly to X-rays.

③ Therapeutic results can be achieved in a short period

For example, kidney cancer can be treated in a very short treatment period (an average of 3 weeks). Compared with the X-rays used in radiotherapy to date (6–7 weeks), the number of irradiation sessions can be reduced.

Cancers Indicated for Heavy Ion (Heavy Particle) Beams