Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6190792 | Clinical Radiology | 2015 | 8 Pages |
â¢Peak kilovoltage (kVp) can be reduced to decrease radiation dose and increase contrast attenuation at a cost of increased image noise.â¢Utilizing iterative reconstruction can decrease image noise and increase contrast to noise ratio (CNR) independent of kVp.â¢Iterative reconstruction adequately compensates for increased image noise associated with low dose low kVp imaging while improving CNR.â¢An ASiR level of approximately 50% at 100 kVp yields similar noise to 120 kVp without ASiR.
AimTo determine the level of iterative reconstruction required to reduce increased image noise associated with low tube potential computed tomography (CT).Materials and methodsFifty patients underwent CT colonography with a supine scan at 120Â kVp and a prone scan at 100Â kVp with other scan parameters unchanged. Both scans were reconstructed with filtered back projection (FBP) and increasing levels of adaptive statistical iterative reconstruction (ASiR) at 30%, 60%, and 90%. Mean noise, soft tissue and tagged fluid attenuation, contrast, and contrast-to-noise ratio (CNR) were collected from reconstructions at both 120 and 100Â kVp and compared using a generalised linear mixed model.ResultsDecreasing tube potential from 120 to 100Â kVp significantly increased image noise by 30-34% and tagged fluid attenuation by 120Â HU at all ASiR levels (p<0.0001, all measures). Increasing ASiR from 0% (FBP) to 30%, 60%, and 90% resulted in significant decreases in noise and increases in CNR at both tube potentials (p<0.001, all comparisons). Compared to 120Â kVp FBP, ASiR greater than 30% at 100Â kVp yielded similar or lower image noise.ConclusionsIterative reconstruction adequately compensates for increased image noise associated with low tube potential imaging while improving CNR. An ASiR level of approximately 50% at 100Â kVp yields similar noise to 120Â kVp without ASiR.