Proton Therapy in Japan – A visit to Southern Tohoku Proton Therapy Center

This past Saturday I had the pleasure to visit the head-operations for the Southern Tohoku Healthcare Group and learn all about Proton Therapy in Japan. This impressive medical complex is located in Koriyama, Fukushima about 250 kilometers from Tokyo and can be reached in about 80 minutes via Shinkansen (bullet train).

The complex houses the Southern Tohoku Research Institute for Neuroscience, general hospital, medical clinic and an ophthalmic clinic. This is also the location of the Southern Tohoku Proton Therapy Center.

Most of us who have not had to deal with the difficult decisions of the best options for cancer treatment may not be familiar with Proton Therapy in Japan.  Japan is a leader in this technology, a pioneer with some of the first facilities and currently houses 23% of worldwide proton therapy centers.

Proton beams, unlike X-rays stop after striking the target and are able to pinpoint tumors with less damage to healthy cells than traditional radiotherapy.

Proton Therapy in Japan is therefore often used with cancers that were previously difficult to treat only with traditional surgery, chemotherapy or radiotherapy. These include prostate cancer, liver cancer, brain, cervical and optical tumors and pediatric cancers.

Once a patient is determined to be suitable for Proton Therapy, he or she will usually require a week of preparation at the hospital. This is follwed by the treatment itself which consists of a series of 30-minute sessions over a period of somewhere between four days and eight weeks, depending on the particular cancer being treated.

The facility in Southern Tohoku is a clean, modern and patient-friendly environment. As a patient, all you most likely will see is the helpful staff as they guide you to a bed in a room that rotates around as the proton beam delivers this highly effective treatment.

During my visit our hosts were gracious enough to take us behind the scenes to get an idea how the whole thing works.

The equipment required to generate a proton beam that travels at over 200,000 kilometers per second is massive and looks like something out of a Sci-fi movie.


In order to generate the proton beam with enough energy to do the job an accelerator and a synchrotron are required. This elaborate equipment appears to take up close to a football field of space. Here is what is going on in the circle of metal piping and boxes.

It all starts with hydrogen atoms that are separated into negatively charged electrons and positively charged protons. They are accelerated and then enter the synchrotron where they circle around at 2/3 the speed of light. The protons move through a beam-transport system that shape and focus the proton beams as they are carried to the treatment room. The treatment room rotates around the patient to deliver the beam to the area of treatment. Patient-customized guides and positioning devices ensure further pin-point accuracy.

According to the hospital there are certain cancers that are not good candidates for Proton Therapy (i.e. gastric, colon and rectal cancer). Tumors over 12 cm can only be partially treated and therefore Proton Therapy is less effective. Late stage cancers where metastasis to other organs or lymph nodes has occurred are not treatable through this method – although head and neck cancers where the lymph nodes have previously been surgically addressed may be viable candidates.

Many thanks to Southern Tohoku Research Institute for Neuroscience for taking the time on a Saturday to teach us about Proton Therapy, provide the tour of their extensive facilities and explain the numerous diagnostic and treatment options at their state-of-the-art facilities.