Isotopes 101

What are they?

Isotopes are microscopic radioactive particles. For medical purposes, these particles can be injected into the body for detection and treatment of illnesses such as cancer and heart disease.

The science of using these isotopes for detection and treatment is called nuclear medicine.

How are they used?

Isotopes emit energy, which can be caught on film by specialized imaging equipment. The images give doctors a more complete picture of the diseased tissues than external radiation treatments.

While they have an important diagnostic function, the energy given off by isotopes is also effective at destroying diseased cells, such as cancer cells. They can be directed specifically at cancer cells, leaving healthy cells untouched.

One disadvantage to medical isotopes is that they can lose their radioactivity relatively quickly. Some of the most widely used types of isotopes have half-lives of just a few days. Since they cannot be stockpiled, production must remain constant to prevent supply disruptions.

Who makes them?

The largest producer of the world’s isotopes is the National Research Universal reactor in Chalk River, Ont. The 52-year-old reactor produces half of the world’s medical isotopes, enough to treat 20 million patients a year. These isotopes are sent to 80 countries.

McMaster University in Hamilton, Ont. has a reactor able to produce medical isotopes, but does not have the capacity of the NRU reactor at Chalk River.

There are also reactors in the Netherlands, Belgium, France and South Africa. All of these reactors are over 40 years old.

In January 2008, the NRU reactor was shut down for four weeks after a routine maintenance check found inadequate safety provisions at the plant. The shutdown caused a worldwide shortage of isotopes.

In 2008, AECL abandoned the two new reactors that were supposed to replace the NRU reactor. The twin MAPLE-1 and -2 reactors, also at Chalk River, both ran into repeated technical problems and breakdowns after hundreds of millions of dollars in construction costs.