Nuclear medicine relies on isotopes, which are chemically similar atoms of differing neutron numbers and masses. Radioisotopes release radiation that can destroy diseased tissue and can be tracked in some conditions in order to return to a healthy mass, making them useful for medical imaging and cancer therapy, as well as monitoring environmental change in oceans and soil, researching the fundamental science of nuclei, and maintaining national security. Radiation is commonly thought to be hazardous to the human body, but radioisotopes for medical use are extremely useful in medicine, especially for disease diagnosis and treatment.

Technetium

Radioactive isotopes are used in nuclear medicine in a number of ways. One of the most common applications is as a tracer, which includes ingesting, injecting, or inhaling a radioisotope such as technetium-99m into the body. The radioisotope is then circulated across the body or picked up by specific tissues. According to the radiation it emits, its distribution can be tracked. Depending on the radioisotope used, the emitted radiation can be captured using various imaging techniques such as single-photon emission computed tomography (SPECT) or positron emission tomography (PET). Physicians may analyze blood flow to particular organs and determine organ function or bone density using this type of imaging. Radioisotopes typically have short half-lives and typically decay before their emitted radioactivity can cause damage to the patient’s body.

Molybdenum-99

Researchers have used their electron linear accelerator to help two companies demonstrate new methods for producing molybdenum-99, the parent isotope of technetium-99m, a medical isotope that may be in short supply. The laboratory is also expanding its radioisotope program, with the objective of conducting ground-breaking research and developing and demonstrating the technologies necessary to supply a variety of key radioisotopes through the DOE Isotope Program. Mo-99, which is currently created by fissioning uranium targets in research reactors, has a 66-hour half-life, making it difficult to manufacture and transport across the world until it spontaneously decays into Tc-99m. Several of the world’s main nuclear reactors generating Mo-99 have undergone unplanned shutdowns, disrupting the Mo-99 radioisotope supply. They were built 30 to 50 years ago at the height of the Atoms for Peace period.

Holmium-166

The radionuclide holmium-166 has been used as a medical isotope for a long time and has a wide variety of applications. The isotope holmium-166 is appealing since it emits both high-energy beta and gamma radiation, which can be used for medicinal purposes and nuclear imaging. Furthermore, due to its paramagnetic properties, holmium-165 can be visualized by MRI and CT due to its high density. Since holmium-165 has a natural abundance of 100%, the only by-product is metastable holmium-166, and nuclear reactor-related holmium-166 does not require any expensive chemical purification steps. Several compounds labeled with holmium-166 are now used in patients, such Ho166-labelled microspheres for liver malignancies, Ho166-labelled chitosan for hepatocellular carcinoma (HCC), and [166Ho]Ho DOTMP for bone metastases. The outcomes in patients are very promising, making this isotope more and more interesting for applications in interventional oncology. 

The primary goal of radioisotope for medical therapy is to kill the cells that are being attacked. Radioisotopes for Medical treatment (Radiotherapy), which is widely used to treat cancer and other disorders involving excessive tissue growth, such as hyperthyroidism, is based on this approach. Radiation therapy for cancer involves bombarding the patient’s tumor with ionizing radiation, which is usually administered in the form of beams of subatomic particles such as protons, neutrons, or alpha or beta particles, which destroy the atomic or molecular structure of the targeted tissue. Ionizing radiation causes breaks in the double-stranded DNA molecule, which kills cancer cells and prevents them from reproducing.  While radiotherapy is associated with unpleasant side effects, it generally is effective in slowing cancer progression or, in some cases, even prompting the regression of malignant disease.