Final answer:
A radionuclide is used for either diagnosis or treatment in medicine, often incorporated into radiopharmaceuticals for imaging or used in radiotherapy to target cancer cells. Their ability to penetrate tissue and be accurately traced makes them invaluable in both diagnostic and therapeutic applications.
Step-by-step explanation:
A radionuclide is a radioactive nuclide that is used in medicine either for the diagnosis or treatment of various conditions. In diagnosis, radionuclides are incorporated into compounds known as radiopharmaceuticals, which are designed to target specific areas or functions within the body. These compounds can then be traced using radiation detectors to identify and diagnose medical issues, as their distribution and concentration provide valuable information about bodily functions or the presence of disease.
For therapeutic purposes, radionuclides are used in radiotherapy where the ionizing radiation they emit is directed to treat ailments, particularly cancer, by damaging the DNA of cancerous cells. The capabilities of radionuclides to easily penetrate tissue and be traced accurately make them extremely useful in both diagnosing and treating a wide range of medical conditions.