A 60Co source with activity 10.00 MBq is embedded in a tumour (mass 0.500kg). The source emits n photons with average energy 1.25MeV. Only half the photons are absorbed in the tumour, the remainder escape.
a. What energy (in J) is delivered to the tumour per second?
b. Calculate the dose absorbed by the tumour delivered per second (in Gy/s)?
c. What exposure time is required for an effective dose of 2 Sv? The half-life of 60Co is 5.27y. Do you need to take into account the fact that the activity decreases as a function of time to calculate this exposure time?
d. If an alpha emitter with the same activity and energy as the 60Co source were used, what exposure time would you need to achieve the 2 Sv?