Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT.
10.3348/kjr.2012.13.6.711
- Author:
Hye Jeon HWANG
1
;
Joon Beom SEO
;
Jin Seong LEE
;
Jae Woo SONG
;
Song Soo KIM
;
Hyun Joo LEE
;
Chae Hun LIM
Author Information
1. Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea. seojb@amc.seoul.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Iterative reconstruction in image space;
Chest CT;
Radiation dose reduction;
Image quality
- MeSH:
Adolescent;
Adult;
Aged;
Female;
Humans;
*Image Processing, Computer-Assisted;
Male;
Middle Aged;
*Radiation Dosage;
Radiographic Image Enhancement;
*Radiography, Thoracic;
Tomography, X-Ray Computed/*methods;
Young Adult
- From:Korean Journal of Radiology
2012;13(6):711-719
- CountryRepublic of Korea
- Language:English
-
Abstract:
OBJECTIVE: To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. MATERIALS AND METHODS: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. RESULTS: Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. CONCLUSION: IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.
