Radioisotopes: Medical and Industrial Applications
Tracers
Radioisotopes are used as tracers in various applications, including:
- Medical diagnostics: Tracers are used to investigate a patient’s body without surgery. Beta or gamma emitters, such as Technetium-99 and Iodine-123 (used to investigate the thyroid gland), are commonly employed.
- Environmental monitoring: Tracers help track the dispersal of waste materials.
- Industrial applications: Tracers can locate leaks or blockages in underground pipes.
Smoke Alarms
Many smoke detectors contain Americium-241, an alpha particle emitter. Its long half-life ensures slow decay and prolonged functionality.
Dating
Radioactive dating techniques determine the age of materials:
- Uranium-lead dating: By comparing the amounts of uranium and lead in a rock sample, its approximate age can be determined. Uranium undergoes a series of decays, ultimately forming stable lead.
- Carbon-14 dating: This method is used for dating organic materials (living things).
Gamma Rays and X-Rays
Both gamma rays and X-rays are electromagnetic waves with very short wavelengths, making them highly energetic. Their penetrating nature allows them to pass through the body, making them useful in medical treatments.
X-Rays
X-rays, discovered by Wilhelm Roentgen in the 19th century, are produced in X-ray machines and are a form of ionizing radiation. They can penetrate skin, muscles, and fat. Due to their potential effects on actively dividing cells (embryos and young children), the ALARA (As Low As Reasonably Achievable) principle is followed:
- Time: Minimize exposure time.
- Distance: Maximize distance from the source.
- Shielding: Use lead screens for protection.
X-rays are used to detect lung or breast cancer (mammography), kidney stones, cysts, and tumors. Computed tomography (CT) scans combine X-rays with computer technology for detailed imaging.
Gamma Radiation
Gamma radiation is emitted from the nucleus of an atom. After emitting an alpha or beta particle, the remaining protons and neutrons in the nucleus may rearrange to a lower energy state, releasing gamma radiation without changing the element.
Uses of Gamma Radiation
Radiotherapy
Gamma radiation is used to treat cancer:
- Cobalt-60 is a commonly used gamma-emitting radioactive material for cancer treatment.
- High doses of high-energy radiation can be used as an alternative to surgery.
- Radiation is often used after surgery to ensure all cancerous cells are destroyed.
- Residual cancerous cells can multiply and cause secondary cancers.
Sterilization of Surgical Equipment
Gamma radiation effectively kills bacteria, making it suitable for sterilizing hospital equipment and preventing the spread of disease. Items are sealed in bags and exposed to intense gamma radiation.
Food Sterilization
Irradiating food with gamma rays can kill bacteria and prevent spoilage. In the UK, irradiation has been permitted for herbs and spices since 2005. Irradiated food must be labeled accordingly. Irradiation does not affect the taste and significantly extends shelf life.
Radioactive Changes
Radioactive isotopes are atoms of the same element with the same number of protons and electrons but different numbers of neutrons. Radioactive decay occurs when unstable atoms with specific combinations of protons and neutrons in their nuclei randomly emit radiation, causing the nucleus to change. For example, Carbon-11 is radioactive, while Carbon-12 is not. The emission of alpha and beta particles produces an atom of a different element, known as the “daughter product” or “decay product.”