Feasibility Of Low-dose Scans In Lumbar Vertebrae By Iterative Image Reconstruction Of Dual-source CT

Objective:To compare radiation dose and image quality of the lumbar vertebrae produced by low-dose dual-source CT scan, Sinogram Affirmed iterative reconstruction (SAFIRE) with conventional-dose scan,filter back-projection (FBP) reconstruction, to explore the feasibility of dual-source CT iterative reconstruction at the low dose scanning of lumbar vertebrae.Methods:120 patients have waist pain history which undergoing lumbar CT scan were randomly divided into A, B, C groups, group A(the conventional-dose group) set the tube voltage 120 kv, tube current 300mAs,using FBP reconstruction; group B (the lower tube current group) set the tube voltage 120 kv, tube current 150mAs, group C (the lower tube voltage group) set the tube voltage 100 kv, tube current 220mAs.Three groups adopt automatic tube current modulation technology scans. B and C groups were treated with SAFIRE reconstruction which intended end radiation dose was 50% less than that of group A. According to the exposure metering formula E=K(V)n.mAs recorded and calculated radiation dose indicator for each case (CTDILOV, DLP, ED), compare the objective evaluation indexes:the signal-to-noise ratio (SNR), the contrast-to-noise ratio between intervertebral disc and the dural sac (D-D CNR) and the subjective scores of different reconstruction image of the every interest (ROI) at L4/5 level. Using statistical analysis.Results:The average radiation dose of group B decreased about 62% than group A, the SNR of every ROI and DNR had no significant difference compared with group A(P>0.018). Compared with group A, the average radiation dose of group C reduced about 70%, in addition to L5 vertebrae body, all ROIs objective image quality is lower than that of group A (P<0.018); in addition to the vertebral small joint, A and B group has no significant difference in subjective image score. kappa value of Two observer change from 0.64 to 0.81, show a good consistency.Conclusion:Compared with conventional-dose with FBP, Lumbar CT low dose scanning based on SAFIRE (the tube current reducing conventional 50%) combined with automatic tube current modulation technique can significantly reduce the radiation dose, but not affect image quality, so it should be as lumbar vertebral disease screening program.