The Optimum Program Of Mono-energetic Imaging Technology Of Dual Energy CT In Visualization For Rib Trauma Fixed With Metal Fixator

Background and Objective The thoracic injury could bring about fracture of rib,multiplace and multiple fracture of ribs often cause dyspnoea,shock and so on,and may proceed to result in death from respiratory failure if not have immediate treatment.There are two methods for clinical conservative treatment and internal fixation after operation,the former has many disadvantages such as long period of hospitalization,many complications of convalescence while the latter can significantly reduce postoperative complications and shorten the recovery period.K-wires and nickel-titanium alloy and other materials has been widely used in the field of thoracic surgery which treat multiple rib fracture in the open reduction.However,these surgical equipment produce a large amount of metal artifacts for conventional CT and affect the observation or evaluation of the disease condition.The scanning mode of the latest dual-energy CT can emit high and low energy rays through two tubes,then a mono-energetic image can be reconstructed after processing,the selection of purified high mono-energetic image can effectively remove the hardened linear beam artifacts.And compared to other dual-energy technologies,the dual-source dual-energy technology has significant advantages in areas like purification of energy spectrum,intelligent tube current adjustment,Iterative reconstruction,etc,it obtain the best artifacts-removed image and reduce the radiation dose effectively.This article is to study the optimum program of mono-energetic spectral imaging technology of dual-energy CT in visualization for patients with chest trauma and fractures fixed with metal fixator.Methods Selected 75 patients with fractures by chest trauma fixed with metal fixator(all fixed materials are grip-type of Ni-Ti alloy plates)as research subject.Divided them into 5 groups randomly,15 in each group,dual-source dual-energy CT scanning,of which,Group A: supine position + CARE Dose4 D + 80/SN140 k V check,rated tube current(tube A:207m As,tube B:88m As);Group B: supine position + 80/SN140 k V check,tube current(tube A:207m As,tube B:88m As);Group C: supine position + CARE Dose4 D + 100/SN140 k V check,rated tube current(tube A:103m As,tube B:88m As);Group D: supine position + CARE Dose4 D + 140/80 k V check,rated tube current(tube A:205m As,tube B:41m As);Group E: semi-reclining position + CARE Dose4 D + 80/SN140 k V check,rated tube current(tube A:207m As,tube B:88m As),note that the angle of tilt should be reduced appropriately when the patient is not tolerant;Collect checked data and compare the 5 groups of volume CT dose index(CTDIvol),dose length product(DLP)and effective dose(ED).Selected 3 fixators from each patient randomly,and spectral curve analysis was carried out on the acquisition of data to obtain the minimum CT differential energy points and calculated the biggest nail area of low density artifacts(S,cm2),overall image contrast of signal to noise ration(CNR)and the quality of images were subjectively graded by a 4-score method.Observe when the lowest energy level can eliminate the false fracture line around alloy plate,distinguish the true fracture line then record the ke V.Results CTDIvol,DLP and ED were significantly lower in group E than that in group B,C,D,and slightly lower than that in group A.The quality of images and the area of low density artifacts(S)in group E are better than that in group A,B,C,D.There are no differences in CNR between group E and group A,B,C but better than that in group D.The false fracture line can be eliminated significantly around the lowest energy level 90 ke V,as the true fracture line can be distinguished.Conclusion 1.The dual-energy technology of dual-source CT can be applied to reduce metal artifacts in thoracic region,and the effect is better than other technical methods.2.The use of semi-reclining position,CARE Dose4 D,combined with 80/SN140 k V tube voltage combination,and then when process,the use of analysis of mono-energy curves to define the optimum mono-energetic point rapidly allow for significant dose reduction and the best personalized image for patients with chest trauma and fracture with metal fixator.