While the x-ray doses from standard abdominal and pelvic CT scans can be relatively high, QCT bone density testing uses lower quality, noisier images and thicker scan slices than normal which reduces the x-ray dose considerably. Combined with the dose reduction algorithms on modern CT scanners, these low-dose CT scan protocols mean that the amount of radiation required is only around 500-800μSv which is comparable to a set of mammograms or around 1/4 of annual background radiation (depending on where you live).