Scientists at the Canadian Light Source have developed a new way to produce critically-needed medical isotopes.

On Nov. 14, the CLS announced the first batch of radioisotopes produced with a linear accelerator at the Medical Isotope Project (MIP) facility. The project is the first of its kind in the world and could help supplement nuclear reactors’ unreliable supply of isotopes.

Director of accelerators at the CLS Mark de Jong wrote in an email to the Sheaf that the advantages of using a linear accelerator to produce medical isotopes include “fewer regulatory hurdles, no use of enriched uranium and no significant long-term nuclear wastes.”

The MIP uses a particle accelerator to bombard enriched molybdenum-100 metal (Mo-100) with high-energy X-rays, said de Jong. The X-rays knock a neutron out of the nuclei of some of the Mo-100 atoms in the target, converting them to the isotope Mo-99. The Mo-99 decays into technetium-99m (a metastable isomer), which is used for tagging radiopharmaceuticals — pharmaceuticals that contain a radioactive isotope — for medical diagnostic tests. After the Mo-99 has decayed, the remaining Mo-100 in the solution is recovered and recycled into additional targets. 

Radiopharmaceuticals act as a tracer inside the human body. A gamma imaging device easily detects the radioactive tracer atom, allowing researchers to study the function of vital organs and detect ailments like cancer.

The idea to produce medical isotopes with a linear accelerator was hatched in 2008, de Jong said. The proposal for the project was submitted in 2010 and the funding process began in 2011.

The nuclear reactor in Chalk River, Ont. has traditionally produced Canada’s medical isotopes. Constructed in 1945, the facility supplies nearly a third of the world’s medical isotopes, said Shane Timm from the Saskatoon Health Region’s medical imaging department.

“There was a large medical isotope shortage a few years ago and it was a global crisis,” said Timm.

The aging Chalk River reactor was shut down for repairs in 2007, creating a worldwide shortage. The facility is scheduled to be retired permanently in 2016.

“Historically, we’ve relied on these reactors to produce isotopes,” Timm said. “If a nuclear reactor goes down, it becomes crippling.”

Approximately 50 scans, called conventional nuclear medicine exams, are performed on Saskatoon patients every day. In Canada, 5,000 scans are performed daily.

The MIP “gives us a secure supply of technetium,” Timm said. “The medical isotopes that they’ve produced at the synchrotron are the isotopes that we use on a daily basis.”

Besides not producing nuclear waste, the most important advantage over nuclear reactors is that linear accelerators can be repaired far more quickly, requiring weeks or days to fix. A nuclear reactor can be out of commission for a year if it breaks down.

The next step for the project is to receive Health Canada approval, which it expects to have within two years.

“We are starting biological, or human, trials so we can present a package to Health Canada,” said radiopharmacist Kennedy Mang’era.

Mang’era works for the Prairie Isotope Production Enterprise (PIPE) in Winnipeg, Man. PIPE is responsible for converting nuclear reactors’ Mo-99 into technetium to be shipped all over the world.

MIP is going to “provide a diversified option,” Mang’era said. He is confident that linear accelerators like MIP will eventually replace nuclear reactors as a main source of medical isotopes, even if it takes many years.

“It’s going to be a while before we can fully replace reactors,” Mang’era said. “You would need 50 to 100 linear accelerators to replace one nuclear reactor.”

Currently, MIP has the capacity to provide enough nuclear isotopes to supply Saskatchewan and Manitoba. Two or three linear accelerators would be needed to supply all of Canada when Chalk River stops production.

Timm says the prospect of replacing nuclear reactors with linear accelerators for medical isotope production is a “game-changer.”

“It’s a testament to the collaboration between Saskatchewan and Manitoba,” said Mang’era.

De Jong said the project was a collaboration between the CLS, National Research Council Canada, Mevex Corporation, PIPE and independent consultants William Diamond and Herb Moore. Funding for the research included a $10-million grant from Natural Resources Canada and another $2 million dollars from the Government of Saskatchewan.

“Today’s achievement is welcome news for Canadian families and our communities,” said Member of Parliament for Saskatoon-Rosetown-Biggar Kelly Block in a press release. “Our investments in new technologies are supporting new milestones and contributing to reliable global supplies of medical isotopes.”