MCQ Detailed View

Cobalt (Co) is a transition metal that has important applications in cancer therapy, specifically in radiotherapy. The isotope Cobalt-60 (⁶⁰Co) is radioactive and emits gamma rays, which are highly penetrating and can destroy cancerous cells. This property makes it extremely useful in cobalt therapy, a type of external beam radiotherapy used to treat tumors and cancers of various organs.

Cobalt-60 is produced by neutron irradiation of Cobalt-59 (⁵⁹Co) in nuclear reactors. The emitted gamma radiation can be precisely directed to the affected area, minimizing damage to surrounding healthy tissue. This makes cobalt therapy an effective treatment for conditions such as skin cancer, cervical cancer, and brain tumors. Cobalt therapy was widely used in the mid-20th century and continues to be employed in many countries, although modern linear accelerators have largely replaced it in some regions.

Other elements listed in the options are not commonly used for cancer therapy. Iron (Fe) is an essential element in the body but does not have radioactive isotopes suitable for direct radiotherapy. Nickel (Ni) is also not used in cancer treatment due to lack of suitable radioactive isotopes and high toxicity. Radon (Rn) is a radioactive noble gas, but its uncontrolled emission and high radiotoxicity make it unsuitable for therapy; historically, it was sometimes used in sealed sources for treatment but is no longer considered safe.

Cobalt’s application in cancer therapy highlights the intersection of inorganic chemistry and medical science. Understanding its properties, particularly the behavior of radioactive isotopes and gamma radiation, is important in both chemistry and medical physics.