Cobalt-60 decays with a half-life of 5.27 years into nickel-60, which then promptly emits two gamma rays with energies of 1.33 MeV and 1.17 MeV in equal amounts. These rays are widely used in treating cancer. a) What is the mass of a 1000 Curie source? b) Assuming that 2.0% of the gamma rays from this source reach a 70-kg patient and the 50% of these gamma rays deposit all their energy in the patient, what is the dose rate in rad/s? c) How long should the patient be exposed to this source if a dose of 30 Rem is required? (The RBE for these gamma rays is 0.7)

Cobalt-60 decays with a half-life of 5.27 years into nickel-60, which then promptly emits two gamma rays with energies of 1.33 MeV and 1.17 MeV in equal amounts. These rays are widely used in treating cancer. a) What is the mass of a 1000 Curie source? b) Assuming that 2.0% of the gamma rays from this source reach a 70-kg patient and the 50% of these gamma rays deposit all their energy in the patient, what is the dose rate in rad/s? c) How long should the patient be exposed to this source if a dose of 30 Rem is required? (The RBE for these gamma rays is 0.7)