Application Of Flash Thorax Mode Of Second-generation Dual Source Computed Tomography In Chest Scanning Of Children

ObjectiveTo contrast image quality and radiation dose of the traditional mode and Flash thorax mode of second-generation dual source computed tomography, and to evaluate the application value of Flash thorax mode of second-generation dual source computed tomography in chest examination of children.MethodsThis was a retrospective analysis. Thirty children (1-33month) underwent chest scan with Flash thorax mode of second-generation dual source computed tomography and other thirty children (1-33month) with traditional mode. Five of them underwent the two modes at different times. All case were divided randomly. The children of traditional group (15girls and15boys, the mean age,16.88±9.56month; range,0-33month; body weight,29.14±7.24g) were scanned with first-generation dual source computed tomography waiting for sleeping natural or after taking10%chloral hydrate,0.5ml/kg. Scan parameters were as follows:tube current with automatic tube current adjustment technology (Care dose4D),120kV tube voltage, pitch=1.4,24x1.2mm slice acquisition,0.5seconds gantry rotation time. The children of Flash group were scanned with second-generation dual source computed tomography fixed with bandages on scan frames, sedation only when uncooperative. Scan parameters were as follows:tube current with automatic tube current adjustment technology (Care dose4D),120kV tube voltage (consistent with traditional group), pitch=3.0,128x0.6mm slice acquisition,0.28seconds gantry rotation time. The gonads of all children were protected with lead aprons. The effective mAs (eff. mAs), the volume CT dose index (CTDIvol), dose length product (DLP) and scan time were recorded, the effective dose was computed out in every cases. The differences of radiation dose between two scan modes were analyzed using independent samples t test. Image quality were assessed by two pediatric radiologist on a4point scale:0, severe artifacts;2, marked artifacts;3, mild artifacts, not relevant for diagnosis;4, no artifacts present. The degree of interobserver concordance was evaluated with calculation of Kappa statistics.ResultsThe average effective mAs of traditional group and Flash group was (62.87±10.88) and (35.71±8.09) mAs; the average CTDIvol was (3.36±0.58) and (2.02±0.44) mGv; the average DLP was (70.90±16.59) and (46.68±11.01) mGv.cm; the average E was (1.41±0.27) and (0.9±0.17) mSv; the average scanning time was (2.44±0.34) and (0.57±0.06) second. These dose indicators and scanning time of two scan modes were of statistically significant differences. Effective dose of Flash group was below1mSv, scan time was shorter than traditional group apparently. The mean image quality scores for the traditional group and Flash group was (2.25±0.50) and (3.73±0.23). The scores of two groups were of statistically significant differences. Artifacts almost existed in the images of the traditional group, for example in lung parenchymas near the left ventriculars and diaphragmatics, and segmental bronchis and lung-markings were showed indistinct; in contrast, artifacts almost did not in Flash group; artifacts didn’t nearly existed in lung parenchymas near the left ventriculars and diaphragmatics and segmental bronchis and lung-markings were showed distinct. The images of Flash group were better accepted by clinicians, and there was interobserver agreement in diagnostic acceptability. The age and weight of children two groups was weren’t of statistically significant differences (t=-1.81,-2.33, P>0.05).ConclusionFlash thorax mode of second-generation dual source computed tomography of obvious superiority in the chest scanning of children can supply image of good quality and reduce the radiation dose.