放射学组学杂志

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Image Quality and Radiation Dose Comparison between Filtered Back Projection and Adaptive Statistical Iterative Reconstruction in Non-contrast Head CT Studies

Seth Alper, Prasoon Mohan, Ian Chaves, Richard Kane and Joseph Calandra

Purpose: The goal of the study was to compare the total radiation dose and subjective image quality between conventional Filtered Back Projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) in non-contrast head CT. Method: Forty seven patients underwent non contrast head CT with image reconstruction using 100% FBP. The same set of patients underwent subsequent non contrast head CT within 6 months using combination of ASIR and FBP reconstruction. Institutional Review Board approval was obtained. Objective assessment of total radiation dose was obtained by measuring the dose length product (DLP) and effective radiation dose. Subjective image quality was assessed by 2 attending radiologists who were blinded to the scanning technique. All images were graded for sharpness, image noise and overall image quality on a 5 point Likert scale. Both subjective and objective measurements from the two sets of images were compared. Paired Student’s t-Test was used for statistical analysis. Results: There was a significant reduction in DLP with the application ASIR from 1781.7 (310) to 1098.9 (SD 281.4) mGy-cm (p<0.01), resulting in mean total dose reduction of 38.4%. The total effective dose also showed similar reduction from 3.9 (SD 0.68) to 2.4 (SD 0.62) mSv (P<0.01). Subjective score for image noise was 4.44 (SD 0.43) and 4.40 (SD 0.48), before and after application of ASIR, respectively (p=0.59). Overall image quality scores were 4.87 (SD 0.33) and 4.85 (0.36) before and after application of ASIR, respectively (p=0.12). Subjective scores for image sharpness decreased after application of ASIR from 4.94 (SD 0.24) to 4.77 (SD 0.47) (p=0.04) Conclusion: Compared to conventional FBP reconstruction, combination of ASIR with FBP reconstruction results in significant reduction in total radiation dose without affecting the overall image quality in non-contrast head CT.