Question

It has become popular for some people to have yearly whole-body scans (CT scans, formerly called CAT scans), using x-rays, just to see if they detect anything suspicious. A number of medical people have recently questioned the advisability of such scans, due in part to the radiation they impart. Typically, one such scan gives a dose of 12 mSv, applied to the whole body. By contrast, a chest x-ray typically administers 0.20 mSv to only 6.0 kg of tissue. How many chest x rays would deliver the same total amount of energy to the body of a 85 kg person as one whole-body scan?

Answer 1

Dose given by one whole-body scan is 12 mSv

Dose administered by x-ray to only 6 kg of tissue is 0.2 mSv

No. of x-rays required to deliver 12 mSv to 6 kg of tissues is

One X-ray only covers 6 kg of the total body tissues

Number of X-rays required to cover a 85 kg person are

Now, number of X-rays required to deliver 12mSv to a 85 kg body are