Particle accelerators

Medical cyclotron x-ray beam generation

Medical cyclotrons produce proton beams which are used to manufacture radioisotopes. These radioisotopes are injected into a patient before they have a positron emission tomography (PET) scan. The radioactive tracers light up tumours by latching onto cancer cell receptors, making them more easily identifiable and traceable via PET scan. The technology means clinicians can potentially diagnose cancers at earlier stages, plus determine how aggressive the cancer is and the extent to which it has spread. It also enables doctors to better target therapies and monitor cancer growths over the course of treatment to track its effectiveness to help patients avoid unnecessary exposure to harmful over-treatment.

Medical cyclotrons are associated with the treatment of many cancers, including: lymphoma lung, pancreatic, head and neck, breast and prostate cancer. Hospitals in Australia that operate cyclotrons include the Liverpool Hospital, Royal Prince Alfred Hospital and the Macquarie University Hospital in NSW; the Peter MacCallum Cancer Institute and Austin Health & Medical Imaging Australia in Victoria; the South Australian Health and Medical Research Institute; the Royal Brisbane Hospital and Wesley Hospital in Queensland and Sir Charles Gairdner Hospital in WA.

The gases required by a cyclotron depend on its type and size. The largest devices require high purity hydrogen, oxygen, and nitrogen, which are needed in the cyclotron’s ion source and provide the necessary protons. Oxygen is required for the conditioning of the deflectors in the cyclotron. Nitrogen is needed for ventilation of evacuated devices. The ion source uses hydrogen to create a plasma. These gases can be supplied in cylinders are of the highest purity available.

For fluoride ion and isotope production, it is common to use high purity argon and helium to support the process. Nitrogen, carbon dioxide and oxygen are also used for the direct production of radioactive isotopes. The gas mixture known as P10 (10% methane in argon) is also used in gas filled proportional nuclear counters which are integral to the x-ray devices involved in isotope manufacture. At Coregas, we have the right products for these applications and many years' experience supplying customers with gases for isotope production .

Synchrotron x-ray beam generation

A synchrotron is one step beyond the cyclotron in terms of particle accelerator sophistication and the intensity of the resultant light beam. Whilst there are many cyclotrons in Australia and their use worldwide is widespread, there are only a handful of synchrotrons operating around the world. Some are used for medical applications.

Australia has one synchrotron operated by ANSTO at Clayton on the outskirts of Melbourne. It produces light that feeds several beam lines. One of those, the Imaging and Medical beamline (IMBL) was built with considerable support from the National Health and Medical Research Council. It delivers the world’s widest synchrotron x-ray beam.

The IMBL provides medical researchers with dynamic 3D x-ray imaging at such high resolution, it can visualise blood vascularisation, air movement in the lung, and tissue and organ structure in far greater detail than that possible with Magnetic Resonance Imaging. The beamline supports research into the treatment of cancer tumours, chronic lung disease, brain haemorrhage, bone growth and replacement, and various heart-related conditions.

In addition to diagnostic imaging applications, medical researchers work with the IMBL to develop potential new radiotherapy methods that could destroy cancer tumours with minimal disruption to the surrounding healthy tissue.

The Australian synchrotron requires various gases to assist beam generation. Many gases are also required for research that takes place using the various beams that are split off from the particle accelerator. Some of these gases are used to produce isotopes for medical research and other purposes. Example bulk gases, high purity gases and specialty gases mixtures typically required for a large synchroton and the associated research activities might be:

• Nitrogen, which is required in large quantities and would typically be delivered as bulk nitrogen
• Ultra-high purity hydrogen delivered as a specialty gas in cylinders
• Carbon dioxide delivered as food grade gas, or as a high purity specialty gas in cylinders
• Argon 5.0 grade which is a high purity specialty gas supplied in cylinders
• Helium 5.0 grade delivered as a liquid helium in cryogenic dewars
• Helium 5.0 grade in cylinders from the specialty gases range
• Methane at the highest available purity, which is 99.9995% (Methane 5.5 grade)
• Sulphur hexafluoride which is available in cylinders at 5.0 grade for research
• A mixture of 5% hydrogen in a balance of argon
• A mixture of 2.75% oxygen, 16% carbon dioxide in a balance of argon