Which one of the following elements' isotopes is used in the treatment of cancer?
- (a)Iodine
- (b)Sodium
- (c)Cobalt
- (d)Uranium
Correct — C, Cobalt. The radioactive isotope Cobalt-60 emits high-energy gamma rays that are used in radiotherapy to destroy cancer cells, in machines often called cobalt units or cobalt bombs. Its penetrating gamma radiation can reach deep-seated tumours, which is why it became a standard external-beam cancer treatment. The other elements listed are not the standard radiotherapy source for this purpose.
- (a)Iodine — Iodine-131 is used in medicine, but mainly to diagnose and treat thyroid disorders; the external-beam cancer therapy asked for here uses Cobalt-60.
- (b)Sodium — Sodium-24 is used as a tracer, for example to study blood circulation and locate clots, not as the standard cancer radiotherapy source.
- (d)Uranium — Uranium is used as nuclear reactor fuel and in weapons, not as a medical isotope for treating cancer.
Radioisotopes are unstable atoms that emit radiation as they decay, and several have medical uses. Cobalt-60 is a gamma-emitting radioisotope whose penetrating radiation is used in radiotherapy to kill cancer cells.
Link the therapy to a penetrating gamma emitter. Cobalt-60 is the textbook answer for radiotherapy, while iodine and sodium isotopes have their own diagnostic or tracer roles.
- Cobalt-60 is a radioactive isotope that emits high-energy gamma rays.
- Its gamma radiation is used in radiotherapy to destroy cancer cells, in cobalt units.
- Iodine-131 is used mainly for thyroid disorders, and Sodium-24 as a blood-flow tracer.
- Radiotherapy works because radiation damages the DNA of rapidly dividing cancer cells.
- Choosing iodine, which treats the thyroid, rather than the general cancer radiotherapy asked here.
- Confusing a medical isotope with reactor fuel such as uranium.
Asked which element's isotope is used in cancer treatment; recall Cobalt-60 gamma radiotherapy.
UPSC_1999_GS1_Q1251999Cobalt-60 is commonly used in radiation therapy because it emits
- (a) alpha rays
- (b) beta rays
- (c) gamma rays
- (d) X-rays
Answer(c) gamma rays
The same isotope and use. That item asks why Cobalt-60 works in radiotherapy (its penetrating gamma rays), while this one asks which element's isotope treats cancer, namely cobalt.
Which one of the following element's isotope is used in the treatment of cancer?
- (a) Uranium
- (b) Cobalt
- (c) Sodium
- (d) Iodine
Answer(b) Cobalt
An almost identical question from the sibling paper, with the same answer, cobalt, whose isotope Cobalt-60 is used in cancer radiotherapy.
- practice — not a real PYQ
Cobalt-60 is used in cancer therapy because it emits
- (a)alpha rays
- (b)beta rays
- (c)gamma rays
- (d)visible light
Answer(c) gamma rays — deeply penetrating radiation that destroys tumour cells.
- practice — not a real PYQ
Which radioisotope is used to treat disorders of the thyroid gland?
- (a)Cobalt-60
- (b)Iodine-131
- (c)Uranium-235
- (d)Carbon-14
Answer(b) Iodine-131 — taken up by the thyroid gland.