F Macri1, J Greffier2, F R Pereira2, C Mandoul2, E Khasanova2, G Gualdi3, J P Beregi2. 1. Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Department of emergency radiology, "Sapienza" university-hospital Um-berto I, 155, viale del Policlinico, 00161 Rome, Italy. Electronic address: francesco.macri@chu-nimes.fr. 2. Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France. 3. Department of emergency radiology, "Sapienza" university-hospital Um-berto I, 155, viale del Policlinico, 00161 Rome, Italy.
Abstract
PURPOSE: To evaluate the effect of dose reduction with iterative reconstruction (IR) on image quality of chest CT scan. MATERIALS AND METHODS: Eighteen human cadavers had chest CT with one reference CT protocol (RP-CT; 120kVp/200mAs) and two protocols with dose reduction: low-dose-CT (LD-CT; 120kVp/40mAs) and ultra-low-dose CT (ULD-CT; 120kVp/10mAs). Data were reconstructed with filter-back-projection (FBP) for RP-CT and with FBP and IR (sinogram affirmed iterative reconstruction [SAFIRE®]) algorithm for LD-CT and ULD-CT. Volume CT dose index (CTDIvol) were recorded. The signal-to-noise (SNR), contrast-to-noise (CNR) ratios of LD-CT and ULD-CT and quantitative parameters were compared to RP-CT. Two radiologists reviewed the CT examinations assessed independently the quality of anatomical structures and expressed a confidence level using a 2-point scale (50% and 95%). RESULTS: CTDIvol was 2.69 mGy for LD-CT (-80%; P<0.01) and 0.67 mGy for ULD-CT (-95%; P<0.01) as compared to 13.42 mGy for RP-CT. SNR and CNR were significantly decreased (P<0.01) for LD-CT and ULD-CT, but IR improved these values satisfactorily. No significant differences were observed for quantitative measurements. Radiologists rated excellent/good the RP-CT and LD-CT images, whereas good/fair the ULD-CT images. Confidence level for subjective anatomical analysis was 95% for all protocols. CONCLUSIONS: Dose reduction with a dose lower than 1 mGy, used in conjunction with IR allows performing chest CT examinations that provide a high quality of anatomical structures.
PURPOSE: To evaluate the effect of dose reduction with iterative reconstruction (IR) on image quality of chest CT scan. MATERIALS AND METHODS: Eighteen human cadavers had chest CT with one reference CT protocol (RP-CT; 120kVp/200mAs) and two protocols with dose reduction: low-dose-CT (LD-CT; 120kVp/40mAs) and ultra-low-dose CT (ULD-CT; 120kVp/10mAs). Data were reconstructed with filter-back-projection (FBP) for RP-CT and with FBP and IR (sinogram affirmed iterative reconstruction [SAFIRE®]) algorithm for LD-CT and ULD-CT. Volume CT dose index (CTDIvol) were recorded. The signal-to-noise (SNR), contrast-to-noise (CNR) ratios of LD-CT and ULD-CT and quantitative parameters were compared to RP-CT. Two radiologists reviewed the CT examinations assessed independently the quality of anatomical structures and expressed a confidence level using a 2-point scale (50% and 95%). RESULTS: CTDIvol was 2.69 mGy for LD-CT (-80%; P<0.01) and 0.67 mGy for ULD-CT (-95%; P<0.01) as compared to 13.42 mGy for RP-CT. SNR and CNR were significantly decreased (P<0.01) for LD-CT and ULD-CT, but IR improved these values satisfactorily. No significant differences were observed for quantitative measurements. Radiologists rated excellent/good the RP-CT and LD-CT images, whereas good/fair the ULD-CT images. Confidence level for subjective anatomical analysis was 95% for all protocols. CONCLUSIONS: Dose reduction with a dose lower than 1 mGy, used in conjunction with IR allows performing chest CT examinations that provide a high quality of anatomical structures.
Authors: Johannes Clemens Godt; Cathrine K Johansen; Anne Catrine T Martinsen; Anselm Schulz; Helga M Brøgger; Kristin Jensen; Arne Stray-Pedersen; Johann Baptist Dormagen Journal: Acta Radiol Open Date: 2021-11-18