Feasibility of individualized low radiation dose chest enhanced CT imaging: phantom and clinical study / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the effect of the combination of Auto-prescription and ODM full on image quality and radiation dose of chest enhanced CT inorder to explore the feasibility of individualized low radiation dose chest enhanced CT. Methods:The phantoms PH-75 in two sizes were scanned with four scanning modes group A, 120 kVp + Smart-mA; group B, 120 kVp + Smart-mA+ ODM full; group C, Auto-prescription + Smart-mA; group D, Auto-prescription + Smart-mA+ ODM full. The images of each group were reconstructed with 40%-80% ASIR-V (interval 20%), recorded as A 1-3-D 1-3. Image quality and radiation dose were evaluated in order to obtain optimal scanning modes. Totally 35 cases(from the First Hospital of Dalian Medical University during November 2021 to July 2022) of chest enhancement CT were collected prospectively in the clinical study using the parameters of D 2 group recorded as D patients. Patients in this group received chest enhancement CT scanning for the second time within three months. The CT parameters in first enhanced scanning recorded as A patient were as same as those in group A 1, and the parameters in second scanning recorded as D patient were as same as those in group D 2. The SNRs, CNRs, subjective grading and imaging findings of the lesion in two groups were compared. Results:In phantom study, the radiation dose of each group was statistically significant, and that in D group was the lowest. For two sizes of phantoms, A 1 was uesd as the control group in pairwise comparison. The SDs of B 1, C 1, and D 2 images had no statistical difference with that of A 1 ( P > 0.05), and SD of D 1was higher than that of A 1, and SDs of other groups were lower than that of A 1( F=10.77, 122.50, P<0.05). CNR of B 1 had no statistical difference with that of A 1, and the CNRs of other groups were higher( F=136.20, 30.21, P<0.05). Subjective scores of A 2, C 2, D 2 had no statistical difference with that of A 1 and those of other groups were lower than that of A 1( H=52.89, 43.95, P<0.05). In clinical study, 80 kVp was uesd for 22 cases and 100 kVp was used for 13 cases in D patients group. SNRs and CNRs in the D patients group were all higher than those in the A patients group ( P > 0.05). The consistency of image quality scores for two observers was good ( kappa = 0.754, P < 0.05). The median scores of the two groups were (4, 4). Conclusion:Auto-prescription combined with ODM full in chest enhanced CT imaging can achieve individualized low radiation dose with meeting the requirements of image quality and clinical diagnosis.