What is heavy ion radiotherapy?
”Heavy ion beams” refer to the nuclei of carbon (neon, etc.) atoms that are deprived of their electrons. X- and gamma rays are used for conventional radiotherapy, and their features are a higher radiation dose around the body surface, which gradually decreases in the body. Conversely, heavy ion beams form a high-dose area at a certain depth and a low-dose in the surrounding area. Therefore, if the peak of the dose of carbon ion beams is adjusted to the position and size of the lesion, the lesion receives a larger dose physically and biologically than the surrounding healthy tissue. In short, carbon ion beams can affect only cancer lesions. It is also possible to treat deep cancer which is difficult to treat by conventional radiotherapy (X- or gamma rays). It is for these characteristics that carbon ion radiotherapy is the solution for cancer treatment.
However, because carbon ion radiotherapy is called “sharp scalpels”, its application requires extremely advanced technology. Various techniques are required, such as adjusting the energy provided and accurately adjusting the maximum dose to the target by tuning the beam.
＜Characteristics of Carbon ion radiotherapy＞
・Irradiate only cancer lesion
・Minimize adverse effects on healthy tissue
・Strong killing power for cancer lesions
・Reduce the burden on a patient
・Effective for radiation-resistant cancer
・No pain and no excision
According to the statistics of the Ministry of Health, Labor and Welfare, cancer has been the leading cause of death in Japan since 1981, and approximately 30% of the total deaths are from cancer. Currently, the main methods of treating cancer are surgery, radiotherapy, and chemotherapy, and the appropriate method is taken depending on the type and progress of the cancer. As mentioned above, because it has strong killing power for cancer lesions and has little effect on healthy tissue, carbon ion radiotherapy is a more effective treatment method than conventional X-ray radiotherapy.
Operation of heavy ion medical accelerator
Accelerator Engineering Corporation (AEC) is a company that supports the operation and maintenance of heavy ion medical accelerators as well as treatment planning support.
Particle radiotherapy that is effective in cancer treatment is becoming widespread throughout the country, and professional skills in the operation and maintenance of such a state-of-the-art system are required. AEC lives up to the expectations as a pioneer in this field and helps to protect precious lives through huge and precise state-of-the-art equipment.
A small high-performance fifth-generation heavy ion radiation therapy machine—the Quantum Scalpel—
Even if the system goes down, immediate recovery is required to continue treatment. Medical accelerator operations and maintenance require technologies in a wide field, such as radiation, physical measurement, beam analysis, microelectronics, mechatronics, optical measurement, electromagnetic measurement, ultra-high vacuum, high frequency electric field, cooling, and control systems.
AEC provides system engineering technology for integrated device management based on these required technologies. With advanced accelerator operation technology, we live up to the expectation of beam stability and reproducibility that meet the strict medical requirements in the fields of heavy ion generation, acceleration, beam transport, and irradiation field formation and quality assurance. Therefore, in addition to daily work such as adjustment and maintenance of various equipment , monitoring of trend data, maintenance of vacuum in the beamline, high-level management of high-power appliances and high- voltage / high-frequency power supplies, adjustment of various electromagnets and beam monitors, we carry out various preservation / maintenance work to produce the stability and reproducibility of the precise beam, such as maintaining the performance of various equipment, and preventive parts replacement. With the know-how accumulated in this way, we will not only respond speedily in the event of equipment abnormality or failure, but also make full use of the beam parameter history data accumulated over many years and the advanced technical capabilities obtained from the field results. Thus, we contribute to ensuring and improving the quality of the treatment beam.
The Heavy Ion Medical Accelerator in Chiba (HIMAC), a heavy ion radiotherapy device of the National Institutes for Quantum Science and Technology (QST), is the first dedicated machine for heavy ion cancer therapy in the world. HIMAC has changed the history of conventional radiotherapy by making full use of various state-of-the-art technologies and comprehensive system engineering. HIMAC was developed by the National Institute of Radiological Sciences (NIRS) and was completed in March 1994. It is said that HIMAC is a crystallization of accelerator science and technology in Japan.
HIMAC is a huge medical accelerator complex housed in a building 65 m wide, 125 m long, 16 m above ground, and 20 m underground. The beam flow to the treatment room is as follows; heavy ions are generated from a heavy ion source. These heavy ions are transferred to the injector and accelerated to approximately 11% of the speed of light by two types of linear accelerators (RFQ Linac and Alvarez Linac). These heavy ions are accelerated to approximately 84% of the speed of light (go around the earth 6.3 times per second) by the main accelerator (synchrotron) and transported to the QST Hospital treatment room. QST Hospital has advanced heavy particle beam treatment with the rotating gantry and scanning irradiation method which improve the efficiency of beam use and minimize adverse effects on healthy tissue.
Not only research on radiation physics necessary for oncology but also basic research on physics and other fields are conducted in the general-purpose physics irradiation room, the secondary beam irradiation room. Radiobiology research with tissue or small and medium-sized animals is conducted in the biological irradiation room.