The operation of the bowtie filter in x-ray CT is correct if the object being scannedis properly centered in the scanner’s field-of-view. Otherwise, the dose delivered to thepatient and image noise will deviate from optimal setting. We investigate the effect of miscen-tering on image noise and surface dose on three commercial CT scanners. Six cylindrical phan-toms with different size and material were scanned on each scanner. The phantoms werepositioned at 0, 2, 4 and 6 cm below the isocen ...