Radiology Which of the following radioisotopes is commonly used as a source for external beam radiotherapy in the treatment of cancer patients A Strontium - 89 B Radium - 226 C Cobalt - 59 D Cobalt - 60 💡 Explanation Which of the following radioisotopes is commonly used as a source for external beam radiotherapy in the treatment of cancer patients ✓ Correct Answer: D. Cobalt - 60