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- Kalra, Mannudeep K., et al.
(författare)
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Radiation Dose Reduction with Sinogram Affirmed Iterative Reconstruction Technique for abdominal Computer Tomography
- 2012
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Ingår i: Journal of Computer Assisted Tomography. - USA : Lippincott Williams & Wilkins. - 0363-8715. ; 36:3, s. 339-346
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The objective of this study was to assess the effect of Sinogram Affirmed Iterative Reconstruction (SAFIRE) and filtered back-projection (FBP) techniques on abdominal computed tomography (CT) performed with 50% and 75% radiation dose reductions.Methods: Twenty-four patients (mean age, 64 ± 14 years; male-female ratio, 10:14) gave informed consent for an institutional review board–approved prospective study involving acquisition of additional research images through the abdomen on 128-slice multi–detector-row CT (SOMATOM Definition Flash) at quality reference mAs of 100 (50% lower dose) and 50 (75% lower dose) over a scan length of 10 cm using combined modulation (CARE Dose 4D). Standard-of-care abdominal CT was performed at 200 quality reference mAs, with remaining parameters held constant. The 50- and 100-mAs data sets were reconstructed with FBP and at 4 SAFIRE settings (S1, S2, S3, S4). Higher number of SAFIRE settings denotes increased strength of the algorithm resulting in lower image noise. Two abdominal radiologists independently compared the FBP and SAFIRE images for lesion number, location, size and conspicuity, and visibility of small structures, image noise, and diagnostic confidence. Objective noise and Hounsfield units (HU) were measured in the liver and the descending aorta.Results: All 43 lesions were detected on both FBP and SAFIRE images. Minor blocky, pixelated appearance of 50% and 75% reduced dose images was noted at S3 and S4 SAFIRE but not at S1 and S2 settings. Subjective noise was suboptimal in both 50% and 75% lower-dose FBP images but was deemed acceptable on all SAFIRE settings. Sinogram Affirmed Iterative Reconstruction images were deemed acceptable in all patients at 50% lower dose and in 22 of 24 patients at 75% lower dose. As compared with 75% reduced dose FBP, objective noise was lower by 22.8% (22.9/29.7), 35% (19.3/29.7), 44.3% (16.7/29.3), and 54.8% (13.4/29.7) on S1 to S4 settings, respectively (P < 0.001).Conclusions: Sinogram Affirmed Iterative Reconstruction–enabled reconstruction provides abdominal CT images without loss in diagnostic value at 50% reduced dose and in some patients also at 75% reduced dose.
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- Kalra, Mannudeep K., et al.
(författare)
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Sinogram-Affirmed Iterative Reconstruction of Low-Dose Chest CT: Effect on Image Quality and Radiation Dose
- 2013
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Ingår i: American Journal of Roentgenology. - : American Roentgen Ray Society (ARRS). - 0361-803X .- 1546-3141. ; 201:2, s. W235-W244
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE. The purpose of this study is to compare sinogram-affirmed iterative reconstruction (SAFIRE) and filtered back projection (FBP) reconstruction of chest CT acquired with 65% radiation dose reduction.SUBJECTS AND METHODS. In this prospective study involving 24 patients (11 women and 13 men; mean [+/- SD] age, 66 +/- 10 years), two scan series were acquired using 100 and 40 Quality Reference mAs over a 10-cm scan length in the chest with a 128-MDCT scanner. The 40 Quality Reference mAs CT projection data were reconstructed with FBP and four settings of Safire (S1, S2, S3, and S4). Six image datasets (FBP with 100 and 40 Quality Reference mAs, and S1, S2, S3, S4 with 40 Quality Reference mAs) were displayed on a DICOM-compliant 55-inch 2-megapixel monitor for blinded evaluation by two thoracic radiologists for number and location of lesions, lesion size, lesion margins, visibility of small structures and fissures, and diagnostic confidence. Objective noise and CT values were measured in thoracic aorta for each image series, and the noise power spectrum was assessed. Data were analyzed with analysis of variance and Wilcoxon signed rank tests.RESULTS. All 186 lesions were seen on 40 Quality Reference mAs SAFIRE images. Diagnostic confidence on SAFIRE images was higher than that for FBP images. Except for the minor blotchy appearance on SAFIRE settings S3 and S4, no significant artifacts were noted. Objective noise with 40 Quality Reference mAs S1 images (21.1 +/- 6.1 SD of HU) was significantly lower than that for 40 Quality Reference mAs FBP images (28.5 +/- 8.1 SD of HU) (p andlt; 0.001). Noise power spectra were identical for SAFIRE and FBP with progressive noise reduction with higher iteration SAFIRE settings.CONCLUSION. Iterative reconstruction (SAFIRE) allows reducing the radiation exposure by approximately 65% without losing diagnostic information in chest CT.
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- Pourjabbar, Sarvenaz, et al.
(författare)
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Preliminary Results : prospective clinical study to assess image-based iterative reconstruction for abdominal computed tomography acquired at 2 radiation dose levels
- 2014
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Ingår i: Journal of computer assisted tomography. - : Lippincott Williams & Wilkins. - 0363-8715 .- 1532-3145. ; 38:1, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:The objective of this study was to compare image quality for abdominal computed tomographic (CT) images acquired at 200 and 50 mA s and reconstructed with image-based iterative reconstruction.MATERIALS AND METHODS:In this institutional review board-approved prospective study, 22 patients (mean [SD] age, 64.3 [14.4] years; male-female ratio, 12:10) gave informed consent for acquisition of additional abdominal CT images on 64-slice multi-detector CT (MDCT) (Siemens Definition Flash). Standard-dose images were acquired at 200 quality reference mA s, whereas low-dose images were acquired at 50 mA s (all series: 120 kV; 5-mm section thickness; pitch, 0.9:1). The low-dose images were reconstructed with a nonlinear 3-dimensional iterative image reconstruction (3D-IIR) (SafeCT; MedicVision, Tirat Carmel, Israel) (4 settings, namely, A1, A2, A3, and A4) and were assessed by 3 abdominal radiologists for lesion detection, image noise, and visibility of small structures. CATPHAN 500 was scanned at the respective doses to obtain noise spectral density and modulation transfer function.RESULTS:Subjective image noise was unacceptable at 50-mA s filtered back projection and improved to average in 50-mA s A1 and minimal or no noise in 50-mA s A4. However, the visibility of small structures was similar to standard-dose filtered back projection images on 50-mA s A2. Objective image noise was reduced to 66% for the 50-mA s 3D-IIR images (9.08 [2.3]/26.75 [6.8]). The modulation transfer function curve demonstrated resolution improvement in the low-dose images with the 3D-IIR technique, whereas the noise spectral density curve confirmed noise suppression in the 50-mA s 3D-IIR images.CONCLUSIONS:Three-dimensional iterative image reconstruction helps to lower image noise without affecting the visibility of small structures at "moderate" settings. Diagnostically acceptable abdominal CT examinations can be acquired at 75% lower-radiation dose with the help of the image-based iterative reconstruction technique.
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