Lowering the Dose in Head CT Using Adaptive Statistical Iterative Reconstruction

Abstract

BACKGROUND AND PURPOSE:While CT has found wide use in medical practice, it is also a substantial source of radiation exposure and is associated with an increased lifetime risk of cancer. There is an urgent need for new approaches to reduce the radiation dose in CT. In this regard, ASIR is an alternative method to FBP. We assessed the effect of ASIR on dose reduction in adult head CT.

The Use of Adaptive Statistical Iterative Reconstruction in Pediatric Head CT: A Feasibility Study

“…We found that CSF demonstrated significantly decreased noise in our ASIR examinations relative to our FBP examinations, while the other tested densities (WM, bone, air) did not demonstrate any significant noise differences between the 2 groups. This is similar to the findings of Kilic et al, 21 which they attributed to the propensity of ASIR to disproportionately reduce noise in smoother areas. 31 We also found that our subjective image scores for image artifacts tended to be lower in our ASIR examinations (Fig 5).…”

“…29 Our findings of a 22% reduction in the average CTDI vol and a 24% reduction in the average DLP when using 20% ASIR, at no significant detriment to subjective image quality, are consistent with the prior published results performed in adults (Fig 4). Kilic et al 21 consecutively performed nonenhanced head CT scans in 149 patients; the first 51 patients underwent their original FBP protocol, and the remaining 98 patients underwent their lower-dose IR protocol reconstructed at 30% ASIR. The group reported a 31% decrease in the average DLP of their ASIR studies, without a significant change in image quality or interpretability.…”

“…The scale that we used to assess subjective image quality was based from the scale used by Kilic et al 21 in their subjective analysis. Subjective image noise was assessed on a 4-point scale: 1 ϭ least noise, too little noise (below average noise); 2 ϭ optimum noise (average noise); 3 ϭ noisy but permits evaluation (above average noise); and 4 ϭ too much noise so that no information can be gathered.…”

“…Recent publications have explored the use of IR in adult head CT with both ASIR 21 and IRIS, 22 and these studies suggest that a 20%-30% dose reduction in head CT is feasible in adults by using these iterative techniques with preservation of image quality. To our knowledge, no studies have been performed to assess the potential use of iterative reconstruction techniques to reduce pediatric head CT dose.…”

Dynamic perfusion CT in brain tumors

“…The effective doses with current techniques are between 2.5 and 5.5 mSv for tube currents of 100-190 mA [49]. Recent advances in adaptive statistical iterative reconstruction can reduce imaging dose without compromising the diagnostic acceptability [50]. An image filtering technique called principal component analysis can also improve PCT image quality; thereby presenting another opportunity for further dose reduction [51].…”