Carbon ion therapy machines are changing quickly. QST Hospital in Japan first used multi-ion therapy, combining carbon with oxygen and helium ions, for a sarcoma patient in 2023, and since November 2024 it has been running a phase I clinical trial for head and neck cancer. Development of the "Quantum Scalpel", a system small enough to fit in an ordinary hospital building, continues step by step, and Mayo Clinic in the United States is building a center that aims to start carbon ion therapy in 2028. More than 50,000 patients worldwide have already received carbon ion therapy. This article summarizes the next-generation equipment and the treatment available in Japan today. To find out whether you can be treated now, contact us for an eligibility and cost consultation.
What does a carbon ion therapy machine look like?
A carbon ion therapy machine strips electrons from carbon atoms, accelerates the ions to very high speed and delivers them to the tumor. It consists of an ion source, a linear accelerator (injector), a synchrotron that raises the energy on a circular orbit, a beam transport line and the irradiation system in the treatment room. Because carbon ions are heavy, strong magnets are needed to bend them, so the whole system has traditionally filled an entire building.
According to Japan's National Institutes for Quantum Science and Technology (QST), the first-generation machine that began treatment in Chiba in 1994 measured about 60 m by 50 m and needed a dedicated building. Second- and third-generation machines installed in Gunma, Saga, Kanagawa, Osaka and elsewhere are about one-third that size. QST also notes that about 3,600 patients a year receive carbon ion therapy at facilities in Japan. The Bragg peak principle is explained on What Is Carbon Ion Therapy?
Better equipment has also shortened courses. QST reports that stage I non-small cell lung cancer went from 18 fractions (6 weeks) to 1 fraction (one day), hepatocellular carcinoma from 15 fractions (5 weeks) to 2 fractions (two days), and prostate cancer from 20 fractions (5 weeks) to 12 fractions (3 weeks). Shorter schedules mean shorter stays in Japan. See our treatment period article.
What is different about multi-ion therapy?
Until now, carbon ion machines have used carbon ions only. Multi-ion therapy chooses different ions for different parts of the tumor. Ions heavier than carbon, such as oxygen or neon, damage cells more strongly and are aimed at the radioresistant center of the tumor, while lighter helium ions cover the edge next to normal tissue. The goal is a stronger effect on the tumor and gentler treatment of normal tissue.
The Japan Atomic Industrial Forum (JAIF) reported in April 2024 that QST and Sumitomo Heavy Industries developed a multi-ion source in 2022 and installed it at the HIMAC accelerator in Chiba. The first patient, with bone and soft tissue sarcoma, received 16 fractions in November and December 2023. Carbon and oxygen beams were used on the same day for the first time and switching went smoothly. The patient was discharged the day after treatment ended, and no early side effects were seen two months later. Eligibility for sarcoma is summarized in bone and soft tissue tumors.
Next, QST Hospital started a phase I trial of multi-ion therapy (MULTI-ION-HN-I, jRCTs032240451) in November 2024 for inoperable head and neck malignancies. According to the protocol published in BMJ Open in 2025, helium, carbon, oxygen or neon ions are used alone or in combination, delivering 57.6–70.4 Gy (RBE) in 16 fractions over 4 weeks. Up to 18 patients will take part, and safety within 90 days of starting treatment is assessed to build the basis for wider use. Current standard treatment is covered in our head and neck cancer article.
How small are the machines becoming?
QST calls its next-generation machine the "Quantum Scalpel" and publishes goals for each generation (updated January 2026). The final target is to fit the whole system within 20 m by 10 m so it can be installed in existing hospital buildings. Smaller machines would allow more carbon ion cancer centers and less travel for patients.
| Generation | Size (vs. 1st) | Key technology | Status |
|---|---|---|---|
| 1st | Baseline (about 60 m × 50 m) | Large carbon-only synchrotron | Treating patients in Chiba since 1994 |
| 2nd and 3rd | About 1/3 | Compact accelerator, rotating gantry | In clinical use across Japan |
| 4th | About 1/20 | Compact superconducting synchrotron, multi-ion irradiation | In development; multi-ion trial under way |
| 5th | About 1/40 | Laser injector, high-temperature superconducting gantry, precision irradiation | Component demonstrations |
The key is superconducting magnets. QST explains that magnets cooled without liquid helium could shrink today's synchrotron, about 20 m in diameter, to about one-tenth the size. The current rotating gantry, 11 m in diameter and 13 m long, is to be cut to about half in both dimensions so it fits a standard radiotherapy room. A prototype magnet built with Kyoto University, Toshiba and KEK transported carbon beams stably at about 2.5 tesla. A laser-driven injector has been shown to cut the roughly 15 m linear accelerator to one-third of its length. For clinical results with a rotating gantry, see our choroidal melanoma article.
How many carbon ion cancer centers are there worldwide?
The Particle Therapy Co-Operative Group (PTCOG) counts about 56,000 patients treated with carbon ions worldwide by the end of 2023. An international white paper in the International Journal of Particle Therapy (2026) also reports that more than 50,000 patients have received carbon ion therapy, with Japan the largest contributor. Japanese centers pool results through the J-CROS network, and HIT (Heidelberg, Germany), CNAO (Italy) and MedAustron (Austria) continue research with carbon and helium ions.
| Region / institution | Recent news | Source |
|---|---|---|
| QST Hospital, Japan (Chiba) | First multi-ion patient (2023); head and neck phase I trial (from November 2024) | JAIF, BMJ Open |
| Mayo Clinic, USA (Jacksonville) | New cancer building opened June 2025; protons planned for 2027, carbon ions for 2028 | Mayo Clinic, State of Florida |
| Cyclhad, France (Caen) | New facility aiming to offer multi-ion therapy | IJPT white paper (2026) |
| HIT, CNAO, MedAustron (Europe) | Carbon and helium ion treatment and research | IJPT white paper (2026) |
Mayo Clinic opened the 228,000-square-foot Duan Family Building in Jacksonville, Florida, in June 2025. It is designed to deliver both protons and carbon ions to the same tumor, and Mayo has worked with Hitachi since 2019. In April 2026, Mayo Clinic Magazine described the team's goal of opening new paths for hard-to-treat cancers such as glioblastoma and pancreatic cancer. When the first carbon ion center in the Americas opens, experience gained in Japan and Europe is expected to reach many more patients.
What do you need to prepare for treatment in Japan now?
There is no need to wait for next-generation machines. Carbon ion therapy in Japan is available today at seven facilities, with results built up for prostate, head and neck, bone and soft tissue sarcoma, pancreatic, liver and lung cancers, among others. Overseas patients first send medical records so the hospital can review eligibility. See Japanese Institutions for how each hospital accepts international patients.
- Recent medical certificate and clinical summary (in English or Japanese)
- Original CT, MRI and PET images (DICOM on CD) with reports
- Pathology report from biopsy
- Records of previous surgery, chemotherapy and radiotherapy (including radiation dose records)
- Recent blood tests and a list of current medications
Carbon ion therapy cost varies by hospital and cancer type, and overseas patients pay as self-pay patients. Published fees and their reference dates are collected in our cost comparison article. Send us your records and we will help you decide which hospital to contact first and how long you may need to stay.
FAQ
Q. Can I receive multi-ion therapy now?
QST Hospital is offering it within a clinical trial, so patients who meet the trial criteria can take part. The hospital decides after reviewing medical records. Even outside the trial, standard carbon ion therapy can often treat the same cancer.
Q. Will new machines give better results?
Compact and multi-ion technologies aim to bring treatment to more hospitals and protect normal tissue better. Good results are already reported with current machines for many cancers, so it is better to discuss available treatment now rather than delay.
Q. When will the Mayo Clinic carbon ion center open?
According to Mayo Clinic and the State of Florida, proton therapy is planned for 2027 and carbon ion therapy for 2028. Today, carbon ion therapy is available at existing centers in Japan, Europe and China.
Q. Does the cost depend on the type of machine?
Cost depends on the hospital, cancer type and insurance status rather than the machine. Overseas patients pay as self-pay patients; published fees with reference dates are in our cost comparison article.
Related articles
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- Quantum Scalpel project — QST (updated 2026-01-15)
- QST Begins Multi-Ion Heavy Particle Cancer Treatment — JAIF (2024-04-17)
- Ikawa H, et al. Multi-ion therapy for head and neck cancers: phase I protocol (MULTI-ION-HN-I). BMJ Open 2025;15:e098151
- Thariat J, et al. Clinical White Paper: Clinical Expansion of Carbon Ion Facilities Worldwide. Int J Part Ther 2026;19:101290
- PTCOG — Particle therapy facilities and patient statistics
- Mayo Clinic News Network — heavy particle therapy in the Americas (2025-06-11)
- State of Florida — Mayo Clinic Jacksonville carbon ion therapy program (2026-01-15)
- Mayo Clinic Magazine — Leading the Charge in Carbon Ion Therapy (2026-04)
General information based on public sources; not a substitute for diagnosis or treatment. Eligibility is decided by the treating physicians. Written by the FTH editorial team.