About CanProbe

The Canadian Molecular Probe Consortium (CanProbe) is a not-for-profit joint venture created by the Centre for Probe Development and Commercialization (CPDC) and the University Health Network (UHN).​ Located at the Toronto General Hospital, CanProbe provides UHN-affiliated and other Ontario hospitals with hundreds of doses of cutting-edge radiopharmaceuticals. These radiopharmaceuticals are primarily used for Positron Emission Tomography (PET) scans and assist doctors in diagnosis and treatment planning for patients with cancer and other serious diseases.

What is a cyclotron?

A cyclotron is a machine that is used to produce radioactive isotopes. The machine accelerates particles (such as hydrogen ions) to a very high speed and directs them into a target where a controlled reaction forms a radioactive isotope. For example, in order to make Fluorine-18 (F-18), which is by far the most common isotope used for PET imaging, the beam is directed onto a target containing water enriched with the non-radioactive isotope Oxygen-18 (O-18).

CanProbe Cyclotron 

How are isotopes turned into radiopharmaceutical products?

Once the radioactive isotopes have been created by the cyclotron, chemistry techniques are used to incorporate these isotopes into radiopharmaceuticals for medical imaging and research. In the case of Fluorine-18 (F-18), the isotope would likely be bound to tracers commonly used to scan cancer patients for diagnosis or treatment planning, or they may be used in research or clinical trials.

Most of the chemistry work is done in sealed, lead-lined "hot cells".  The lead lining shields the radiation so that staff handling the radioactive material do not receive any radiation exposure.

CanProbe Hot Cells

Currently the only isotopes produced using the CanProbe cyclotron are Fluorine-18 and Nitrogen-13.  Gallium-68 is also obtained in the facility from a generator supply.

Are there any risks to individuals working at UHN or living nearby?

No. Cyclotrons have been built and operated worldwide since the 1930s, and are considered to be a clean and safe nuclear technology. It is important to note that the cyclotron cannot operate or produce radioactivity without electrical power. Unlike a nuclear reactor, a cyclotron can simply be shut off like a light bulb. The CanProbe facility has also been designed to ensure radiation exposure to any adjacent area is actually kept below normal background levels. For example, although the cyclotron unit itself is relatively small, much of the space in the facility is taken up by extra thick concrete and lead walls.

Staff members who work at CanProbe have received specialized training to work safely with radioactive material. The facility also contains several safety monitoring systems, security features and interlocks which are tested on a regular basis. Special ventilation systems guard against accidental releases of radioisotopes outside the facility and were designed to ensure that even in a worst-case scenario that there would be no measureable risk to the public. Emissions from the facility are monitored continuously. Since CanProbe began operations in 2013, there have been no releases at levels that would be significant to our staff, patients or community.

Does the facility produce radioactive waste?

CanProbe produces very little radioactive waste. All radioactive isotopes have "half-lives," which is the time it takes for half of a given sample of a radioactive materials to undergo radioactive decay. This means that after one half-life, half of the material is no longer radioactive. Most isotopes produced from a cyclotron have very short half-lives; for F-18, the half-life is just under 2 hours. The table below shows how much of a sample would still be radioactive after a certain amount of time has passed.

Half-life1 Hour4 Hours1 Day
Fluorine-18 (F-18)110 minutes69% remaining22% remaining0% remaining
Nitrogen-13 (N-13)10 minutes1.5% remaining0% remaining0% remaining
Gallium-68 (Ga-68)68 minutes54% remaining8.5% remaining0% remaining

Due to the short half-lives, any quantities of radioactivity remaining after production will quickly decay to background levels and the products can then be safety discarded through standard chemical waste streams.

The short half-lives also means that bulk quantities of radiopharmaceuticals cannot be stored for future use and must be produced on a daily basis. This is the reason why more and more hospitals are installing their own cyclotron facilities as demand for these tracers grow; it is far more efficient to generate short-lived isotopes close to the hospital so they can be used before they decay away. The number of isotope production accelerators in Canada, such as cyclotrons, has almost doubled in the last 10 years. There are other several other cyclotrons operating in Toronto as well as in Hamilton, London and Ottawa.

Is the radioactive material transported safely?

The volume of radioactivity produced by the cyclotron is relatively small in scale. A typical production run of F-18 amounts to a volume of less than 20mL, about the same size volume as an espresso coffee. The radiopharmaceuticals are transported from CanProbe in shielded containers that meet international standards. Anyone packaging or transporting radioactive material is also required to have special training in accordance with Transport Canada and federal regulations.

Who has oversight for the cyclotron and its products?

As a facility which produces and uses radioactive materials, CanProbe requires licensing through the Canadian Nuclear Safety Commission (CNSC). The CNSC has regulated the production and use of all nuclear material in Canada since 1946. They are mandated to ensure the safety of staff, public and the environment.

The design of the entire CanProbe facility, including safety considerations for staff and the general public, has been reviewed and approved by the CNSC.  They also review and approve the Radiation Safety program, policies and procedures. As a part of their oversight program, periodic inspections of the facility are performed by CNSC staff members. Regular reports are also made by CanProbe to the CNSC, and licence renewals ensure the regulator reviews the entire operation on a scheduled basis.

For more information on the CNSC visit:

Where can I get more information on radiation and radiation safety in Canada?

The Canadian Nuclear Safety Commission has excellent educational resources about radiation and radiation safety in Canada at the following links:


Any significant events will be posted here for public disclosure in accordance with the CanProbe Public Information and Disclosure policy.

Contact Us

If you have questions about CanProbe, please contact us at the facility: 416 340-4800 ext. 3813 or