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Every day, around 30,000 people benefit from medical examinations thanks to molybdenum-99. This remarkable substance plays a major role in nuclear medicine. But what exactly is molybdenum-99, and what does it mean for hospitals and patients? We’re happy to explain.

What is molybdenum-99?

Molybdenum-99, also known as Mo-99, is a radioactive substance. This means it naturally breaks down over time, releasing radiation in the process. Molybdenum-99 does not occur in nature; it is produced in a nuclear reactor.

It is the “parent isotope” of technetium-99m (Tc-99m), a radioactive material that is crucial for medical imaging. Molybdenum-99 naturally decays into technetium-99m within a few days. This “daughter” isotope is actually the real hero of the story, as doctors use this mildly radioactive substance to clearly visualize the inside of the body.

Technetium-99m remains active only for a short time—just long enough to perform scans after it has been administered. That’s why it’s convenient that hospitals can extract technetium-99m directly from molybdenum-99 using a device called a generator.

Photo of a generator: The inside of a generator, where the molybdenum-99 is safely enclosed. The generator is a shielded container from which hospitals can “harvest” technetium-99m.

Applications in medicine

Technetium-99m is used to create medical images of the body. It helps doctors clearly see how organs are functioning. For example, it can be used to examine the heart, kidneys, lungs, bones, and other parts of the body.

Imagine a doctor wants to check if there’s an issue with the blood flow to the heart. In that case, a small amount of technetium-99m is injected into the patient. To ensure the technetium-99m reaches the heart, it is attached to a molecule known as a carrier molecule. After being injected into a vein, the substance travels to the heart and shows exactly what’s going on there. This allows doctors to clearly visualize heart conditions, including narrowing of the coronary arteries.

A scan typically begins 2 to 4 hours after the injection. If you wait too long, the effectiveness of technetium-99m decreases, which can affect the quality of the images. Based on these scans, doctors can determine whether further testing is needed or if treatment can begin.

Photo of a bone scan: A skeletal scintigraphy image made with a gamma camera, which detects the radiation from technetium-99m and displays it on a monitor.

Production and distribution

Molybdenum-99 is produced in specialized nuclear reactors. In the Netherlands, for example, this is done at NRG PALLAS. There, aluminum plates loaded with uranium are irradiated. This process generates molybdenum-99. Afterward, it is purified and packaged into generators. These generators are then quickly shipped to hospitals around the world.

Inside these generators, molybdenum-99 gradually decays into technetium-99m. This allows hospitals to “harvest” a small amount of the mildly radioactive substance each day for use in medical scans. Since technetium-99m also decays over time, it’s important that it is processed and used without delay.

A small substance with a big impact

Without molybdenum-99, many medical tests and diagnoses would not be possible. It helps doctors detect diseases at an early stage, allowing patients to receive timely and appropriate treatment. Think of thyroid disorders, heart conditions, or cancer metastases in the bones. In this way, molybdenum-99 helps thousands of people every day receive better diagnoses—and a better future.

Molybdenum-99 may be invisible, but it plays a vital role in healthcare. A tiny amount of radiation, with a powerful effect!