Study on Flash scan combined with iterative reconstruction in chest CT scan: image quality and radiation dose

Abstract

Objective To assess radiation dose and image quality of chest CT examinations that acquired with Flash scan technique combined with iterative reconstruction. Methods Thirty continuous patients required no-contrast chest CT with Flash scan mode and contrast enhanced chest CT with conventional CT scan mode. For each examination, the images were reconstructed by filter back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE). The volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED) were estimated. The image noise, signal to noise ratio (SNR), overall subjective image quality, and respiratory motion artifacts were evaluated blindly by two radiologists. Results For Flash scan and conventional scan, SAFIRE reduced the image noise 35% and 16%, respectively; and increased SNR 21.9% and 25% compared to FBP, respectively (P<0.05). There was significant lower subjective image scores acquired by SAFIRE than by FBP. Flash scan reduced the CTDIvol (mGy) 40.9%, DLP 32.1%, and ED 26.9% compared to conventional CT scan mode. The motion artifact scores were reduced significantly with Flash scan mode compared to conventional scan mode. Conclusions Flash scan technique of the chest can obtain image with minimum respiratory motion artifact due to dramatically increased scan speed, and when SAFIRE was combined with, it reduces significantly radiation dose and image noise. Key words: Tomography, X-ray computed; Image processing, computer-assisted; Radiography, thoracic; Radiation dosage