Article

In the Netherlands and around the world, thousands of people are examined every day with a special medical scan: the bone scan. This scan is often used to detect cancer metastases in the bone at an early stage. An important part of the bone scan is technetium-99m, a medical isotope that emits radiation, making abnormalities visible on the scan. "You hope that early detection will lead to a better prognosis, so you can provide the most optimal treatment and the patient has a better chance of survival or can remain symptom-free for a long time," says Marcel Stokkel, nuclear medicine physician at the Netherlands Cancer Institute in Amsterdam.

Bone tissue is alive and is constantly renewed, Stokkel explains. New bone is created and old bone is broken down. "With metastases in the bone, you see that the 'factories' that make bone tissue start working harder. And you can see that quickly on a bone scan, but often not yet on an X-ray. Often you already know that someone has cancer, but you want to know if and where it has spread. That is important to determine the right treatment."

Binding in the bone

But how exactly does technetium-99m work? The substance is linked to a special molecule that specifically searches for bone tissue. There it attaches itself to places where the bone is active. From that moment on, technetium-99m starts to do its job. The substance decays and then emits gamma rays, a special form of energy. This radiation comes from the body and is captured by a scanner, making the bones visible on the image. "In places where there are metastases, more technetium-99m is absorbed than in healthy bone tissue," says Stokkel. "On the scan, those spots look darker or blacker. This way we can often see them before they are visible on a normal X-ray."

A bone scan has several advantages. The entire body can be examined at once, the radiation load is relatively low, and functional changes, such as increased bone activity, become visible earlier than with an X-ray or CT scan. The doctor can then adjust the treatment in the hope of improving the patient's prognosis. "If you know that there are also abnormalities in the bone, your complete treatment plan changes. For example, you can decide to give radiation in addition to surgery for a single metastasis or chemotherapy for multiple metastases. This way, you hope to be there in time for patients and to treat them adequately," says Stokkel.

Indispensable worldwide

Every day, technetium-99m is used for treatment of about 30,000 patients worldwide. The substance is  not only used in bone scans, but also to image the heart, liver and kidneys, among other things. "Without technetium-99m, you not only lose a cheap and simple method to determine the stage of cancer, but also to get a medical image of the organs’ function. The bone scan still remains an important tool; especially as an alternative to more expensive techniques such as the PET scan given it does not show an uptake in the tumor," says Stokkel.

Currently, technetium-99m is mainly produced in the High Flux Reactor (HFR) in Petten, which has been in operation for more than 60 years. To ensure continuity in the future, the new PALLAS-reactor is being built. "The production capacity will also increase considerably, so that more medical isotopes can be supplied," says Stokkel.

Bastion of expertise

Petten has more than 60 years of knowledge, experience and expertise in the field of nuclear technology. "The people there know exactly how a reactor works, how to handle radiation safely and what the market needs. Petten is therefore an important centre for the production of isotopes, a real bastion of expertise. It is therefore logical that the new PALLAS-reactor is being built there."

But what's especially important, according to Stokkel, is that isotopes can not only detect diseases, but also treat patients and improve their outlook. "A lot of research is still needed in this area, especially when it comes to treatments with medical isotopes. Ultimately, you want the best for the patient, and it is precisely in this that these isotopes will play an increasingly important role," says Stokkel.