Question

Calculate the radiation dosage (in grays) for an 85-kg person that is exposed for 3.0 seconds to a 3.0 Ci source of beta radiation. Assume that 100% of the radiation is absorbed and each beta particle has an energy of 1.3× 10–13 J. Answer should be in Gy.

Answer 1

3.0 Ci x (3.7x10^10 decays per sec / 1 Ci ) = 1.11x10^11 decays/second

I found out that absorbed dose (D) is the energy (E) absorbed per unit mass (m) of the absorbing material. The absorbed dose can be calculated by using the following relationship.

D = {E \ m}

The unit of absorbed dose is the gray (Gy) where one gray is one joule per kilogram (J kg-1).

** I just don't understand how to relate D to the decays/second.

The solution wouldn't be as simple as saying:

D = 1.3x10^-13 J /85 kg = 1.52x10^-15 J/kg or 1.52x10^-13 Gy