Technetium-99m

Doctors use a special tool to see inside you.

They use a tiny bit of a special material. This material sends out signals that a camera can see.

This material is very helpful. It is used for millions of medical tests every year. It is the most used kind in the world.

This material does not stay in your body for long. It leaves your body in about one day. This helps keep you safe.

Scientists make this material in special machines. They use a material called molybdenum to make it. This can be sent to hospitals.

It is a very important tool for doctors. It helps them see how your body is working.

Doctors use a special tool called technetium-99m to see inside the body.

It is a medical radioisotope. This means it is a type of material that gives off radiation. It is the most used kind in the world for medical tests.

This material works as a tracer. A tracer is something that travels through the body so doctors can follow it. Technetium-99m gives off gamma rays. These are tiny bits of energy. A special machine called a gamma camera can see these rays.

This helps doctors see how organs like the liver work.

Technetium-99m has a short half-life of about 6 hours. A half-life is the time it takes for half of the material to decay. Because it decays quickly, it does not stay in the body for long. Most of it is gone in one day. This helps keep the amount of radiation low for the patient.

Scientists make it using molybdenum. They use nuclear reactors to turn molybdenum into a material called molybdenum-99. This can be shipped to hospitals. Once at the hospital, the molybdenum-99 turns into technetium-99m.

Technetium-99m is a very important tool in modern medicine. It is a type of radioactive material called a metastable nuclear isomer. This means it is an atom in an excited state that stays that way longer than most. Doctors use it in tens of millions of medical tests every single year. It is the most commonly used medical radioisotope in the entire world.

This material acts as a radioactive tracer. A tracer is something that travels through the body so doctors can track it.

This tracer works by sending out tiny bits of energy called gamma rays. These rays have an energy level of 140.5 keV. This is a good level because it is similar to what X-ray machines use. Medical equipment called gamma cameras can easily detect these rays.

The material has a short half-life of about 6.0066 hours. This is the time it takes for half of the material to decay. Because it decays so fast, 93.7% of it turns into technetium-99 within 24 hours. This quick decay helps keep the total radiation dose low for the patient.

Scientists first discovered this isotope in 1938. Emilio Segrè and Glenn T. Seaborg isolated it using a machine called a cyclotron. They hit molybdenum with particles called 8 MeV deuterons to make it. Later, in 1940, Segrè and Chien-Shiung Wu studied how it appeared in uranium fission. In the 1950s, Powell Richards saw its potential for medical use. He worked at the Brookhaven National Laboratory. By 1960, Richards was the first to suggest using it as a medical tracer.

Making this material is a careful process. Most technetium-99m comes from a parent material called molybdenum-99. This parent has a longer half-life of 2.75 days. Scientists create molybdenum-99 in nuclear reactors by using highly enriched uranium. This longer life allows the molybdenum to be shipped to hospitals. Once it arrives, the technetium-99m is extracted from the sample. In 1958, Walter Tucker and Margaret Greene developed the first generator to do this.

Technetium-99m helps us see how the body works in real time. For example, researchers Sorensen and Archambault showed it could help see the liver. They found that molybdenum-99 could concentrate in the liver to act as an internal generator. This allowed them to visualize the organ using gamma ray emissions. Today, many countries produce these materials. For instance, the NRU reactor in Canada was a large producer for many years. Even though it has been decommissioned, the history of this science continues to help doctors everywhere.

Technetium-99m is a metastable nuclear isomer used globally in medical diagnostics. A metastable isomer is a type of nuclide that exists in an excited state for a longer period than usual. This specific isotope is the most commonly used medical radioisotope in the world. It is used in tens of millions of medical diagnostic procedures every year. Doctors use it as a radioactive tracer to help visualize how the body is functioning.

Because it is so useful, it has become a cornerstone of modern medical imaging.

The isotope works by emitting gamma rays, which are high-energy forms of light. These rays have a photon energy of 140.5 keV. This specific energy level is very helpful because it falls within the range used by conventional X-ray equipment. Medical professionals use specialized machines called gamma cameras to detect these emissions. When the tracer is inside a patient, the camera picks up the rays to create an image. This process allows doctors to see internal organs and biological functions clearly.

Technetium-99m has a physical half-life of 6.0066 hours. The half-life is the time required for half of the radioactive atoms to decay. Within 24 hours, approximately 93.7% of the isotope decays into technetium-99. It also has a biological half-life of about one day based on human metabolism. This combination of short half-lives is vital for patient safety. It allows for rapid data collection during scans while keeping the total radiation exposure to the patient very low. However, these same traits make it unsuitable for therapy. It cannot deliver a strong, localized dose to destroy diseased tissue because it decays too quickly.

Most technetium-99m is produced from a parent isotope called molybdenum-99. This parent isotope has a longer half-life of 2.75 days. To create it, scientists use nuclear reactors to perform fission on highly enriched uranium targets. The molybdenum-99 is then shipped to medical facilities. Once it arrives, the technetium-99m is extracted from the sample as it is produced. In 1958, Walter Tucker and Margaret Greene developed the first technetium-99m generator to handle this extraction.

This system allows hospitals to have a steady supply of the short-lived isotope.

The history of this discovery began in 1938. Emilio Segrè and Glenn T. Seaborg isolated the metastable isotope for the first time. They used a cyclotron to bombard natural molybdenum with 8 MeV deuterons. Later, in 1940, Segrè and Chien-Shiung Wu analyzed uranium-235 fission products and detected the isomer. In the 1950s, Powell Richards recognized its medical potential. He worked at the Brookhaven National Laboratory. By 1960, Richards suggested using it as a medical tracer. In 1963, Sorensen and Archambault demonstrated that injected molybdenum-99 could concentrate in the liver. This allowed them to visualize the organ using gamma ray emissions.

Production has shifted across different countries over the decades. For many years, the NRU reactor in Canada was a major supplier. Between 1967 and 1984, molybdenum-99 was produced for the Mallinckrodt Nuclear Company at the Missouri University Research Reactor. In the United States, Cintichem, Inc. became a single major producer during the 1980s. However, an underground leak in 1989 led to the shutdown of their reactor. This ended commercial production of molybdenum-99 in the U.S. for a time. Other countries like Argentina, Belgium, and South Africa also maintain reactors to support isotope production.

The global supply chain can be sensitive to technical issues. In the late 2000s, the world faced shortages of technetium-99m. This happened because two aging reactors, the NRU and the HFR, provided about two-thirds of the global molybdenum-99 supply. Both reactors faced maintenance issues and shutdowns. The NRU reactor in Canada experienced a heavy water leak in 2009. The HFR reactor in the Netherlands also required safety investigations and repairs. These events highlight how important stable nuclear research facilities are for maintaining the global supply of medical isotopes.