Radiology/CT dosage and effect on other body parts
In 2008 I received an abdominal / pelvic exam with contrast then a few months later a chest CT for lungs, no contrast. I called the hospital a few weeks after to inquire about the radiation I was exposed to for my personal records so I could better weigh out the risks of future tests. I spoke with a woman who led me to believe she was the radiologist who told me that one exam was around 3.4 mGy (which she pronounced "mili-guy") and the other was 2.5 mGy.
I have moved since and unfortunately these records were lost. So I phoned the hospital again this week to replace them. The radiologist I spoke with this time told me back in 2008 they weren't keeping track yet so they don`t have that number on file. She also told me that the doses I was quoted in 2008 were way too low for the exams I had.
So my questions are.
1. Is it even possible to do the exams I mentioned at the radiation doses I was initially quoted and if not could you please give me a more realistic assessment for a male, 6'2", 180 pounds?
2. How directionally focused is the radiation from CT exams like these? For instance, is the risk from an examination of one part of the body elevated by an examination of another part or are the risks predominantly focused on the points of examination?
Radiology.org has a lot of good information for you. Here is an article about the different ways to measure radiation: http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_hiw_09
As for normal radiation doses, look at this page: http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray
From the latter web page, the average dose of a CT Abd/Pelvis w/contrast is 20 mSv (The equivalent dose in milliSievert (mSv) = the absorbed dose in mGy). For a CT of the chest, the average dose is 7 mSv.
The answer to your second question is that there is a certain amount of scatter radiation absorbed by neighboring tissue from indirect exposure. The article about radiation dose has more info on that.
The cumulative effect of the radiation from these exams is minimal. However, the damage from radiation exposure is cumulative. So it is always prudent to minimize your exposure, whenever possible.
Hope this helps,