Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D) improves chest CT image quality and reduces radiation exposure.

Tsuneo Yamashiro,Hiroshi Moriya,Noriyuki Tomiyama,Sadayuki Murayama,Tetsuhiro Miyara,Hisashi Kamiya,For The Investigators Of Active Study Group ,Satoshi Noma,Osamu Honda,Yuko Tanaka,Yoshiharu Ohno,Mitsuhiro Koyama,Ayano Kamiya,Kiyoshi Murata

doi:10.1371/journal.pone.0105735

Abstract

ObjectiveTo assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D) for image quality improvement and dose reduction for chest computed tomography (CT).MethodsInstitutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D). Using a 5-point scale from 1 (non-diagnostic) to 5 (excellent), three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease), and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts). Differences in these scores were assessed by Scheffe's test.ResultsAt each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001) and all mediastinal measurements (p<0.01). For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001), and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA.ConclusionFor chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%.

Highlights

Iterative reconstruction techniques have gradually been applied to several multidetector-row computed tomography (MDCT) scanners, which recently became available due to increased computational power and created a new generation of reconstruction methods after conventional filtered back projection (FBP) and basic image filtering [1,2]
The positive effects of AIDR3D have been investigated for some organs [22,23,24], only a few studies have investigated the advantages of AIDR3D for chest CT [25,26,27]
Significant quality improvements using AIDR3D were observed for lung nodule/mass at 240 mA (p,0.05) and for three lung disease patterns at 120 and 60 mA

Summary

Introduction

Iterative reconstruction techniques have gradually been applied to several multidetector-row computed tomography (MDCT) scanners, which recently became available due to increased computational power and created a new generation of reconstruction methods after conventional filtered back projection (FBP) and basic image filtering [1,2]. The definitions of iterative reconstruction differ among CT manufacturers, iterative reconstruction typically involves multiple iteration cycles during the reconstruction process until final output images are created, and often enhances input images by using various algebraic models rather than simple noise reduction prior to the iterative cycles. AIDR3D incorporates unique noise reduction processing, which includes statistical and scanner models for projection data, and multiple cycles of information syntheses with edge-handling, smoothing, and blending of original input images until final output images are created. The positive effects of AIDR3D have been investigated for some organs [22,23,24], only a few studies have investigated the advantages of AIDR3D for chest CT [25,26,27]

Methods

Results

Conclusion