Question

In the production of radiopharmaceuticals, how is the radioisotope produced? and how is a 'radiopharmaceutical' formed from that radioisotope? What does the radioisotope get attached to in order to become a radiopharmaceutical?

Answer 1

When two elements have the same atomic number, this is, the same number of protons in their nuclei, and the same mass number, this is, the sum of the protons and the neutrons in their nuclei is the same, they are just the same element. But it may occur that two elements have the same atomic number, but different mass number, this is because one of them has more neutrons in its nuclei. These are called isotopes of that element. Radioisotopes are radioactive isotopes of an element. They can also be defined as atoms that contain an unstable combination of neutrons and protons, or excess energy in their nucleus, and emits radiation to stabilize (the process of shedding the radiation is called radioactive decay). They are widely used in medicine, industry, and scientific research.

The unstable nucleus of a radioisotope can occur naturally, or as a result of artificially altering the atom. They can be produced in accelerators (cyclotrons) or research reactors, where the parent nucleid is irradiated. Commonly, in nuclear reactors the parent is bombarded by neutrons, so neutron-rich radioisotopes are devoloped. On the other hand in cyclotrons the parent is bombarded with protons, so proton-rich radioisotopes are developed. Some radioisotopes used in nuclear medicine have short half-lives, which means they decay quickly and are suitable for diagnostic purposes; others with longer half-lives take more time to decay, which makes them suitable for therapeutic purposes.

A radiopharmaceutical is a molecule that consists of a radioisotope tracer attached to a pharmaceutical drug. After entering the body, the radio-labelled pharmaceutical will bind to a biologic molecule and accumulate in a specific organ or tumour tissue. The radioisotope attached to the targeting pharmaceutical will undergo decay and produce specific amounts of radiation that can be used to diagnose or treat human diseases and injuries.