Question

Jack was exposed to fast neutrons; he received a radiation dose of 100 rem on part of his hand, affecting 23.0 grams of tissue. The relative biological effectiveness (RBE) of these neutrons is 8.00.

a) How much radiation did Jack receive? Express your answer in rads to three significant figures.

b) What was the total energy of the radiation Jack received? Express your answer in joules to three significant figures.

c) Suppose Jill received the same rad dosage, but from beta rays with an RBE of 1.40 instead of from neutrons. What is the value of the equivalent dose she received? Express your answer in rems to three significant figures.

Answer 1

GIven

Radiation dose = 100 rem

Mass of tissue , m = 23 g = 0.023 kg

RBE of neutrons = 8

(A)

The radiation received by Jack = Biological dose equivalent (BDE) / RBE --1

= 100 rem / 8

= 12.5 rad

(B)

Since 1 rad = 0.01 J / kg

So, 12.5 rad = 0.01 * 12.5 J / kg = 0.125 J / kg

The total energy of radiation received by Jack = 0.125 J * 0.023 kg /kg = 2.88 *10^-3 J

(C)

For Jill

Absorbed radiation dosage = 12.5 rad

RBE = 1.40

BDE = (Absorbed radiation dosage )* RBE [From eq 1]

= 12.5 rad * 1.40 = 17.5 rem