Friday, February 24, 2006

Gamma radiation dose from radioactive cobalt

Radiation Energy Transfer and Dose

5727Co emits 122 keV gamma-rays. If a 70kg person swallowed a 4 micro Curie sample of this, what would the dose rate (rads/day) averaged over the whole body. Assume that 50% of the gamma ray energy is absorbed by the body.

4 micro Ci is equivalent to 4.0x106*3.7x1010 = 148000 disintegrations per second.

This is equivalent to 148000*122keV*1.6x10-19 J/s = 1.4x10-9 J/s released into the body, which absorbs half of this:

7x10-10 J/s

0.000062 J/day

9x10^-7 J/kg/day

9x10^-5 rad/day

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