OK, I've been "studying" this, so for anyone interested, this is what I figured.

1) The referring doctor will usually play down the radiation levels, and especially the technicians doing the test. The usual comparison to background radiation or to airplane flights is totally unacceptable since they are trying to compare apples and pears.
It is only that certain (scientific or other) authorities and studies will play a different song - radiation in medical imaging is simply quite a concern.

2) The so-called "effective dose" is indeed a flawed concept. It basically looks at the received (or should it be "given") amount of radiation and then calculates (averages) it over the WHOLE body, even when only a small section is scanned (eg. sinuses). To me, this is very wrong (or I have misunderstood the concept).
Different tissues absorb radiation at extremely different levels. Each tissue type has a 'tissue factor' assigned to it. Then they add up all tissues in the body (each multiplied by the tissue factor) and that is your effective dose (also considered is the age and sex somehow - they don't say how). So for some tissues, actual absorbed dose can be 40 mSv, and those tissues are small, but for other, large areas ("tissues"), the dose might be 0.1 Sv. So your lens receive massive amounts of radiation, but they tell you your head CT scan was "only 2 mSv". Scan area is say 30 cm square, but they average the radiation dose over the whole body.

I am also wondering if radiology technicians are required by law to record the exact parameters they adjusted/used for each test, or is this recorded automatically and can't be messed with. Or is it machine-specific?
Are these parameters and doses received (however flawed they may be) easily given to patients?