Abdominal CT radiation dose reduction at Siriraj Hospital (Phase II)

Abstract

Objective: To compare radiation dose, radiologists’ satisfaction, and image noise between the standard dose abdominal CT currently performed at our hospital and the new automatic tube current modulation (ATCM) low dose abdominal CT, using various parameters (0%, 10%, 20%, and 30%) of the Adaptive Statistical Iterative Reconstruction (ASiR). Materials and Methods: We prospectively performed the ATCM low dose abdominal CT in 111 participants who had prior standard dose CT for comparison. The ATCM low dose CT images were post processed with 4 parameters (0%, 10%, 20% and 30%) of ASiR on a CT workstation. The volume CT dose index (CTDIvol) of the ATCM low dose and the standard dose CT were compared. Four experienced abdominal radiologists independently assessed the quality of the ATCM low dose CT with the aforementioned ASiR parameters using a 5-point-scale satisfaction score (1 = unacceptable, 2 = poor, 3 = average, 4 = good, and 5 = excellent image quality) by using the prior standard dose CT as a reference of an excellent image quality (5). Each reader selected the preferred ASiR parameter for each participant. The image noise of the liver and the aorta in all 5 techniques (1 prior standard dose and 4 current ATCM low dose techniques) was measured. The correlation between the image quality vs the participants’ body mass index (BMI) and waist circumferences were analyzed. Results: The mean CTDIvol of the ATCM low dose CT was significantly lower than of the standard dose CT (7.29 ± 0.20 vs 11.28 ± 0.23 mGy, p<0.001). The mean satisfaction score for the ATCM low dose CT with 0%, 10%, 20% and 30% ASiR were 4.14, 4.16, 4.17, and 4.26, respectively with the ranges of 3 to 5 in all techniques. The preferred ASiR parameters of each participant randomly selected by each reader were varied, depending on the readers’ opinions. The mean image noise of the aorta on the standard dose CT and the ATCM low dose CT with 0%, 10%, 20%, and 30% ASiR was 30.69, 36.60, 34.05, 31.43, and 29.09, respectively, while the mean image noise of the liver was 24.96, 29.90, 27.86, 25.66, and 23.68, respectively. There was a correlation between the image quality (satisfaction score and image noise) vs the participants’ BMI and waist circumferences. Conclusion: The ATCM low dose CT received acceptable radiologists’ satisfaction with significant radiation dose reduction. The increment of ASiR was helpful in reducing the image noise and had a tendency to increase the radiologists’ satisfaction score.

Optimizing Computed Tomography Image Reconstruction for Focal Hepatic Lesions: Deep Learning Image Reconstruction vs Iterative Reconstruction

“…Our ndings align with previous studies [30,32,35,40] that reported that higher DLIR or IR strength leads to reduced image noise. We also observed a weak to moderate positive correlation between image noise and both BMI and waist circumference, consistent with prior studies [41][42]. In overweight or obese patients, increased body circumference or thickness hinders photon penetration, resulting in elevated image noise [43][44].…”

Abdominal CT radiation dose reduction at Siriraj Hospital (Phase III)

“…In the quantitative image assessment, the image noise of the aorta and the liver on the FTC and the ATCM low dose abdominal CT were summarized in Table 3. From our previous phase I [7] and phase II [15] studies, both FTC and ATCM low dose abdominal CT provided significant radiation dose reduction compared to the standard dose CT, and at the same time offered acceptable image quality. The purpose of this current phase III study was to directly compare these two aforementioned low dose CT techniques in either image quality or radiation dose.…”

“…Our phase II study [15] was prospectively performed in 111 participants, comparing low dose abdominal CT using the ATCM technique and conventional standard dose CT. The ATCM low dose CT images were post-processed on a CT workstation with 4 parameters of ASiR (0%, 10%, 20%, and 30%).…”