Question

8. A 135 lb person absorbs 3.3 x10-7 J of energy from radioactive emissions. a. How many rads do they receive? b. How many grays do they receive?

Answer 1

We have relation, 1 kg = 2.205 lb

$\therefore$ 2.205 lb / 1 kg = 1 = 1 kg / 2.205 lb

Hence, 135 lb = 135 lb ( 1 kg / 2.205 lb ) = 61.2 kg

Amount of energy absorbed by 61.2 kg of tissue = 3.3 $\times$ 10 ^-07 J

We have relation, 1 Gray = 1 J / kg.

$\therefore$ No. of grays received by person = 3.3 $\times$ 10 ^-07 J / 61.2 kg = 5.4 $\times$ 10 ^-09 J / kg

i e  No. of grays received by person = 5.4 $\times$ 10 ^-09

We have relation, 1 rad = 0.01 J / kg tissue.

i e 1 rad = 0.01 gray

No. of rads received by person = 0.01 (5.4 $\times$ 10 ^-09 ) = 5.4 $\times$ 10 ^-11

ANSWERS : No. of grays received by person = 5.4 $\times$ 10 ^-09

No. of rads received by person =  5.4 $\times$ 10 ^-11