Objective To explore the value of iteration algorithm (AIDR 3D) and filter-back projection (FBP) combined with CT low dose scanning in evaluation of lumbar intervertebral disc hernia.Methods Totally 150 patients with lumbar degenerative osteoarthropathy were randomly divided into A＞E groups,with 30 cases in each group.Scanning parameters of A＞D groups were 120 kV of tube voltage,and 100 mAs,50 mAs,30 mAs,as well as 20 mAs of tube current.While parameters of group E were 80 kV of tube voltage and 100 mAs of tube current.Each group was reconstructed with FBP and AIDR 3D,respectively,and their noises,SNRs and CNRs of groups were compared.And 3-point evaluation method was used to score the imaging,while score ≥2 were acceptable image quantity for clinical imaging.Results Under different radiation doses,AIDR 3D reconstruction images were superior to FBP in noise,SNR,CNR and display of intervertebral disc hernia.Under the same reconstruction technology,with the reduction of dose,noise increased,SNR and display of intervertebral disc hernia decreased.Except for slightly lower in AIDR 3D reconstruction with 50 mAs than that with 30 mAs,CNR decreased with the reduction of dose.Two reconstruction technologies under the same dose,image quality of reducing the tube current were better than that of lowering the tube voltage.Conclusion It is valuable of AIDR 3D combined with CT low dose scanning in evaluation on lumbar intervertebral disc hernia.

Objective:To investigate the effect of ultra-low dose (ULD) computed tomography (CT) scanning on the diagnosis of ankle fractures and the quality of a three-dimensional printing (3DP) model.Methods:This study was a prospective study. A total of 61 patients with clinical ankle fractures treated conservatively in Zhuhai Hospital of Guangdong Hospital of Traditional Chinese Medicine from November 2019 to January 2022 were included in this study. Patients underwent standard dose (SD) CT scan and ultra-low dose (ULD) CT scan, respectively. The tube voltage/tube current of SD and ULD were 120 kV/100 mAs and 80 kV/10 mAs, respectively. Two senior radiologists evaluated the presence of ankle fractures. The effective radiation dose ( E), noise, signal-to-noise ratio (SNR), contrast signal-to-noise ratio (CNR), and CT value of bone cortex minus CT value of peripheral fat (CTc) were compared. The radiologists also evaluated the discoverability, diagnosability, and overall image quality of the fracture line according to Likert′s 5-point scoring method. Two senior orthopedists subjectively evaluated the quality of each 3DP model (model clarity and operation guidance). A score ≥ 3 indicated that the quality of the CT diagnostic image and 3DP model were acceptable. Results:The interval between the two CT scans was (9.23 ± 1.92) d. A total of 94 fracture sites were found. There were no missed diagnosis or misdiagnosis based on the SD and ULD scans.Noise, SNR, and CNR were better on the SD CT scanning ( F=5.92, 9.70, 8.32, P=0.00), however, CTc was higher on the ULD scans ( F=27.55, P<0.01). The image scores of the SD and ULD scans were (4.97 ± 0.18) and (4.21 ± 0.71), and the quality scores of the 3DP model (4.99 ± 0.01) and (4.87 ± 0.34), respectively. The SD scans were better than the ULD scans with respect to CT image quality and 3DP model quality ( Z=-6.88, -2.91, P<0.01), but both were considered suitable to meet clinical needs (all ≥ 3 points). The E associated with SD and ULD scannings were (34.68 ± 4.96) μSV and (1.04 ± 0.10) μSV, respectively. The latter was thus significantly better than the former ( F=38.77, P =0.00). Conclusions:The E value of ULD scanning is about 3.00% of SD scanning E, which can meet the needs of clinical diagnosis of ankle fracture and 3DP model printing diagnosis.