Cobalt therapy is the medical use of ____________ rays from the radioisotope cobalt60 to treat conditions such as cancer.

The correct answer is gamma.

Key Points

• Cobalt-60 decays into a stable Nickel-60 isotope, two wavelengths of high-energy gamma-rays are emitted (1.17 and 1.33 MeV- an average of 1.25 MeV used).
• Cobalt-60 (60Co) has been used for radiotherapy cancer treatment, food irradiation, and industrial applications.
• Gamma rays are electromagnetic radiations of low wavelength, high frequency, and high energy.
• Gamma rays penetrating power is very great and can pass through several centimetres of lead.

Additional Information 

• The phenomenon of self disintegration by emitting certain invisible rays by the naturally occurring substances, elements and its compounds is called radioactivity. 
• The phenomenon of radioactivity was discovered by A.H Becquerel in 1886.
• The three types of radioactive emissions are:
  • Alpha particle: A positively charged helium atom. It has a very less penetrating power.
  • Beta particle: A negatively charged light particle. It has the penetrating power greater than the alpha particle.
  • Gamma particle: A gamma-ray, or gamma radiation, is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei.
• X-rays are a form of electromagnetic radiation that is used for medical imaging, treating cancer and even used for exploring the cosmos.