Physics Nuclear Physics ETEA 2022
PMDC Verified Question 40 of 98
For the treatment of cancer, the source of gamma rays used, is:
A
Co-60
B
Iodine-126
C
Na-15
D
Pb-207
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Co-60


Concept:

External beam radiotherapy requires an intense, reliable source of high-energy gamma photons to destroy deep-seated tumors.

Solution:

  • Cobalt-60 (Co-60) is a synthetic radioisotope that undergoes beta decay followed immediately by the emission of two highly penetrating gamma rays (1.17 MeV and 1.33 MeV).


  • Because of its strong gamma emission and convenient half-life (~5.27 years), it is the global gold standard in "Gamma Knife" surgeries and external radiation therapy.


Why other options are incorrect:

Iodine is used internally for the thyroid. Lead-207 is totally stable. Na-15 is an extreme, instantly decaying isotope not used in medicine.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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