Figure 4. Noise in transaxial CT images obtained at the top of the iliac crest in 11 volunteers. Images were acquired with reduced radiation dose to the volunteer with the CTa system using patient-specific scan parameters (Table 3). The dashed line indicates the highest noise level that would be obtained centrally in the image of a circular water phantom using these scan parameters. Standard deviations were obtained in four regions of interest in homogeneous tissue (central in the left and right psoas muscles (
) and peripheral in subcutaneous fat in the left and right dorsal waist areas( x )).
