Research expands the boundaries of nuclear medicine

Advances in PET scans have enabled the development of a whole new range of medical isotopes. baranozdemir via getty images

Medical isotopes have been the cornerstone of nuclear medicine for decades, but ongoing research is expanding the boundaries of how physicians can identify and treat disease, says Dr. Christopher O’Brien, former president of the Canadian Association of Nuclear Medicine.

For example, the resolution of positron emission tomography (PET) scans is getting down to three to four millimetres, which is a very tiny area in which to detect disease, and medical isotope development is giving physicians a better understanding of what’s on a cell’s surface and allowing them to target more types of disease more effectively, he says.

Nuclear medicine uses radiation to provide information about the functioning of a person’s specific organs, or to treat disease. In most cases, the information is used by physicians to make a quick diagnosis of the patient’s illness. The thyroid, bones, heart, liver and many other organs at a cellular level can be easily imaged and disorders in their function revealed. In some cases, medical isotopes can be used to treat diseased organs or tumours.

“Most of the research being done now is trying to determine what is on the cancer cell that we can detect and kill,” adds Dr. O’Brien.

Advances in PET scans have enabled the development of a whole new range of medical isotopes to target receptors on a cell, which gives physicians greater ability to detect metastatic disease and use radiopharmaceuticals to treat the disease in a very specific way.

“This is called targeted isotope therapy, and it allows us to destroy the cancer cells at a local level,” says Dr. O’Brien. “It gives our oncologists another form of treatment for their patients that will prolong life, and the side-effects are very minimal because you’re targeting the tumour cell itself with little effect on the surrounding cells, so patients don’t have all the side-effects that they used to get with chemotherapy.”

Another component of research, he adds, is in dementia and Alzheimer’s disease and various types of dementing processes.

“There’s been a significant progress in identifying what’s happening in the brain before a patient starts developing the onset of dementia, which
allows researchers and pharmaceutical companies to start developing drugs to perhaps impact the development of dementia before the patient is even demonstrating clinical signs. Earlier intervention is what we are looking at,” says Dr. O’Brien.

Looking to the future of nuclear medicine, he foresees that the specialty will continue as a diagnostic and imaging specialty, but the radioisotope therapy aspect of the speciality will play a greater and greater role in the management of patients who have both benign and malignant disease.

“Working in conjunction with our oncology colleagues, we will have a greater role to play in therapy, helping them manage their patients,” says Dr. O’Brien. “And our therapy will begin at a much earlier stage in the treatment management process. I see the emergence of theranostics – the name being given to it – as part of the future of nuclear medicine.”

Medical isotopes are produced in either nuclear reactors or particle accelerators. Until it was taken out of service in 2018, the National Research Universal reactor at Chalk River Laboratories, Ontario, generated radioisotopes used to treat or diagnose over 20 million people in 80 countries annually.

According to the Canadian Nuclear Association (CNA), in developed countries – which make up 25 per cent of the world’s population – approximately one person in 50 has a nuclear diagnostic procedure each year. In Canada, this means about 760,000 diagnostic procedures and 76,000 radiation therapy procedures each year.

Ontario Power Generation (OPG), notes that approximately 50 per cent of the world’s Cobalt-60 isotope is supplied by its CANDU reactors. The isotope is used to sterilize medical devices and plays an important role in medical imaging and diagnostic procedures, as well as in medicine and new drug development.

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