Question

1. A patient absorbs a 37-rad dose of α-particles (RBE = 20) directly on a tumor. If protons were used instead (RBE = 10), how many rad would be needed to cause the same damage?

2. If an 84 kg person is exposed to 42 mrem of alpha particles (with RBE of 12), calculate the dosage (in rad) received by the person.

 rad

What is the amount of energy absorbed by the person (in J)?

 J

3. A bone was found that has a ratio of C-14 atoms of 0.04 (N/No = 0.04)compared to the same mass of a new bone, how old is the bone? assume the half live of C-14 is 5730 years.

Answer 1

1)

sample od tissue absorb 37-rad dose

dose in REM=does in RAD*REB

=37*20/10

=74 rad

3)

? = the decay constant for the particular radioisotope

The decay constant, ?, which is the same as a rate constant discussed in the kinetics chapter. It is possible to express the decay constant in terms of the half-life, t_1/2:

lemda=0.693/5730=0.000120

t=-(1/0.000120)ln(0.04)

t=26614.94 year