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My son’s doctor told me that one CT scan was = to 200-300 x-rays.

HOWEVER, my son both of those CT scans. Once for head trauma and once for severe chest pain. (The chest pain turned out to be broken rib heads. *Very* painful, but not fatal. But at the time, they thought he had a much more serious problem like air leaking from a lung or a blood clot in the chest cavity. They had to diagnose him in order to treat him fast.)

I believe a chest x-ray is around 80 milirem, so if one was to multiply 80 by 200-300, the exposure is possibly 16,000-24,000 milirem, divided by 1,000, to get the number of rem, which would be 160-240 rem, an astonishingly high exposure. What I don't know, is whether x-rays and gamma rays harm the body equally, so the conversion may be folly.

The NRC sets a lifetime exposure of 50 rem for radiological industry workers. According to the industry standards, a 650 rem, total body exposure, is a lethal dose. 50% of those exposed to 650 rem are expected to die in 2 weeks. What I don't know, is how long the exposure has to be, to the whole body, to get a lethal dose at 650 rem.

Granted, a CT scan is focused, therefore practically the entire body escapes exposure to a high dose of radiation. Not something to take lightly though.

In your son's case, it is easy to discern that, the benefit of knowing how much damage to his body existed internally, versus the exposure, was worth the trade off.

That's one scary injury. Hopefully, he healed up and is healthy as ever.

Health Physics Society webpage.

http://www.hps.org/publicinformation/ate/q1084.html

According to the responder in the link provided, a chest x-ray is 5-10 mrem, and the CT scan is 100-200 mrem.

Here’s part of their response...

Q: How much radiation was I exposed to for the CT sinus exam?

A: The effective dose is around 100-200 mrem. How does this compare to a chest x ray? The effective dose from a single chest x ray is around 5-10 mrem. Is a full-head CT scan more or less radiation than a sinus CT scan? Depends on the radiographic technique and how many pictures are taken. The estimate for the sinus CT would also be applicable for a head CT.