Existence of neutrons was physically proved in 1932. Shortly after that, researchers started to propose ideas to utilize such neutrons in medical treatments. The idea that became reality was the neutron capture method which called for the injection of a specified element into cancer cells and to irradiate neutron rays on such cells to cause damage to the cancer cell. In 1950s, the first treatment of cancer (brain cancer) using an experimental reactor was carried out in the United States.

In Japan, clinical studies on the use of the neutron capture method commenced in 1968. The development of a boron compound, which was found to be easy to incorporate into cancer cells, allowed researchers to carry out multiple clinical studies of this treatment method on brain cancer. One of these research facilities, the Kyoto University Research Reactor Institute (located in Kumatori-cho, Sennan-gun, Osaka) commenced clinical treatment in 1975. Today, it is commonly known that Japan leads the world in Boron Neutron Capture Therapy (BNCT) research.

In BNCT, the boron compound is first injected into a patient through an intravenous drip or other means. Once it has been verified that cancer cells have selectively incorporated the boron into its structure, the patient is radiated with neutrons (thermal neutrons) that have energy levels that are appropriate to the treatment. When this is done, the boron and neutrons cause a nuclear fission reaction and the cancer cells that have incorporated the boron molecules are destroyed.

This method of cancer treatment is a breakthrough because it selectively destroys cancer cells while not harming the surrounding non-cancerous cells. However, the widespread use of this treatment hit a few roadblocks. The first issue was related to the technology behind the boron compound that would be incorporated into the cancer cells. The only isotope of boron that easily causes a nuclear fission reaction is called Boron-10. This isotope needed to be extracted at high concentrations from naturally occurring boron. When the fluorine compound manufacturer, Stella Chemifa Corporation, developed this technology, advancements in BNCT took a huge leap forward.

The other problem was related to the device that would generate the neutrons. Up to now, clinical studies of this treatment method have only been possible at facilities that have a research grade nuclear reactor. These reactors are too large to install such equipment at smaller research or medical facilities. In reality, there was a need for a company to develop a compact neutron generator.

This is where the SHI Group comes into the picture. Through the use of our know-how in PET (positron emission tomography) and proton cancer therapy systems, we were able to develop a compact BNCT accelerator (cyclotron). Since the fall of 2012, clinical trials on BNCT using an accelerator for the first time in the world have been carried out jointly with the Kyoto University Research Reactor Institute and Stella Chemifa Corporation. Further clinical trials to verify the safety of this method will be conducted in the future with the aim to submit an application for approval of medical equipment during 2016 and to obtain an approval of medical equipment.

SHI's BNCT system consists of a cyclotron that emits high powered protons, a beam transportation system that carries the protons to the treatment device, and a neutron irradiator that collides the protons against a metal target (beryllium) to generate neutrons and decelerates the energy of the neutrons before irradiation on a patient.

In the cyclotron, the negative ion of a hydrogen molecule is accelerated. By externalizing the source of ions that generate the negative hydrogen ions, it was possible to make the overall device much smaller while at the same time realizing significant output levels of 30MeV/1mA. Innovation can also be seen in the cooling method of the beryllium target. Unless heat is removed efficiently from this process, the metal target is damaged quickly. In SHI's system, the proton beam follows a circular path to reduce the concentration of heat on the surface of the beryllium, and the cooling water is circulated in a spiral format to effectively achieve heat removal. Even in the material used to decelerate the energy of the neutron, many attempts of trial and error were carried out to find the optimal shape and ratio of metal alloy in the material's composition.

In addition to the clinical trials being carried out at the Kyoto University Research Reactor Institute presently, plans are being made to commence clinical trials at the Southern Tohoku Research Institute for Neuroscience (located in Koriyama City, Fukushima Prefecture) in 2015. This institute is a cutting-edge treatment facility which boasts the first proton therapy device installed at a private medical facility among other equipment. Through the collection of results from the BNCT trials in both Osaka and Fukushima, SHI is aiming to write a new page in advanced cancer treatment methods.