A person with lymphoma receives a dose of 45 Gy in the form of γ radiation during a course of radiotherapy. Most of this dose is absorbed in 18 g of cancerous lymphatic tissue. (a) How much energy is absorbed by the cancerous tissue? (b) If this treatment consists of five 20 minute sessions per week over the course of 5 weeks and just 1% of the γ photons in the γ ray beam are absorbed, what is the power of the γ ray beam? (c) If the γ ray beam consists of just 0.5% of the γ photons emitted by the γ source, each of which has energy of 0.03MeV, what is the activity (in Ci) of the γ ray source?