Impact of adaptive statistical iterative reconstruction on radiation dose in evaluation of trauma patients

Abstract

BACKGROUND A recent study showed that computed tomographic (CT) scans contributed 93% of radiation exposure of 177 patients admitted to our Level I trauma center. Adaptive statistical iterative reconstruction (ASIR) is an algorithm that reduces the noise level in reconstructed images and therefore allows the use of less ionizing radiation during CT scans without significantly affecting image quality. ASIR was instituted on all CT scans performed on trauma patients in June 2009. Our objective was to determine if implementation of ASIR reduced radiation dose without compromising patient outcomes. METHODS We identified 300 patients activating the trauma system before and after the implementation of ASIR imaging. After applying inclusion criteria, 245 charts were reviewed. Baseline demographics, presenting characteristics, number of delayed diagnoses, and missed injuries were recorded. The postexamination volume CT dose index (CTDIvol) and dose-length product (DLP)reported by the scanner for CT scans of the chest, abdomen, and pelvis and CT scans of the brain and cervical spine were recorded. Subjective image quality was compared between the two groups. RESULTS For CT scans of the chest, abdomen, and pelvis, the mean CTDIvol(17.1 mGy vs. 14.2 mGy; p < 0.001) and DLP (1,165 mGy·cm vs. 1,004 mGy·cm; p < 0.001) was lower for studies performed with ASIR. For CT scans of the brain and cervical spine, the mean CTDIvol(61.7 mGy vs. 49.6 mGy; p < 0.001) and DLP (1,327 mGy·cm vs. 1,067 mGy·cm; p < 0.001) was lower for studies performed with ASIR. There was no subjective difference in image quality between ASIR and non-ASIR scans. All CT scans were deemed of good or excellent image quality. There were no delayed diagnoses or missed injuries related to CT scanning identified in either group. CONCLUSION Implementation of ASIR imaging for CT scans performed on trauma patients led to a nearly 20% reduction in ionizing radiation without compromising outcomes or image quality.

Comparing CNR, SNR, and Image Quality of CT Images Reconstructed with Soft Kernel, Standard Kernel, and Standard Kernel plus ASIR 30% Techniques

“…Similar results were obtained with ASIR by Matsuda et al [18] , who evaluated the value of ASIR in CT porto-venography; they found that ASIR helped reduce the noise and improve the CNR of the liver images and the liver vasculature images. Although the ASIR technique has been shown to enable reduce radiation dose without compromising image quality [19] , to our knowledge, no previous studies have evaluated images to assess the effect of the SK technique compared with the ASIR30% and StK techniques. In our study, the SK technique produced better image quality, quantitatively and qualitatively than the StK technique and similar image quality compared to ASIR30%.…”

The use of adaptive statistical iterative reconstruction (ASiR) technique in evaluation of patients with cervical spine trauma: impact on radiation dose reduction and image quality

“…Various studies have reported the benefits of using ASiR techniques in the abdomen, the chest, coronary CT angiography, the head and cervical spine. 7,12,14,15,26,27 ASiR allows the use of a higher scanner NI, which helps in reducing the tube current and radiation exposure. 12,14,15 In the present study, the NI could be increased by 27% after implementation of ASiR in CT scan of patients with blunt cervical spine trauma.…”

“…7,8 ASiR transforms repeatedly the pixel Hounsfield values of an image until they converge on a final value by using matrix algebra. 12 Noise is inversely proportional to the square root of dose. By lowering image noise, this method allows tube current reduction, thus decreasing radiation dose, with recovery of image quality.…”

“…9,25 Most protocols use a blend of ASiR and FBP with 10-40% ASiR settings. 12 In the present study, we chose 30% of ASiR in our low-dose cervical spine protocol based on our initial experience and consensus among the radiologists. Various studies have reported the benefits of using ASiR techniques in the abdomen, the chest, coronary CT angiography, the head and cervical spine.…”

“…9 Noise is iteratively reduced in the image domain. 10 There are very limited numbers of studies in the literature focusing on the role of ASiR in cervical spine CT. 9,11,12 In the present study, we compared the subjective image quality, image noise and radiation dose of cervical spine CT images using reduced dose protocol with ASiR vs reference dose protocol without ASiR.…”