Objective To investigate the value of CARE Dose 4D technique in decreasing radiation dose and improving image quality of multi-slice spiral CT in adult chest scanning.Methods 100patients of chest CT scanning were equally divided into study group and control group randomly.CARE Dose 4D Technique was used in study group.Effective mAs value,volume CT dose index (CTDIvol) and dose length product (DLP) were displayed automatically in machine while chest scanning; those values and actual mAs value of every image were recorded respectively.The image quality at apex of lung,lower edge of aorta arch,middle area of left atrium and base of lung on every image of 400 images was judged and classified as three level (excellent,good,poor) by two deputy chief physicians with double blind method,the image noise at corresponding parts was measured.Results While setting 80 mAs for quality reference mAs,the effective mAs value in study group most decreased 44 mAs than control group with an average decrease of 9.60( 12.0% ) ,CTDIvol with 4.75 mGy with an average decrease of 0.95 mC y( 11.0% ) ,DLP 99.50% in study group,with 98.0% in control group.But it was higher at apex of lung and base of lung,lower at middle area of left atrium,and similar at lower edge of aorta arch in study group than contrast group.The image noise were lower at apex of lung and base of lung in study group than control group (t =6.299 and 2.332,all P ＜ 0.05 ) ,higher at middle area of left atrium in study group than control group (t=3.078,P ＜0.05) and similar at lower edge of aorta arch in study group than control group (t =1.191,P ＞0.05).Conclusions CARE Dose 4D technique provides a function regulated mAs real-time on line,it not only raises utilization rate of radiation and decreases radiation dose,but also promises and increases image quality in chest CT scanning,and has some clinical significance.

A simple, rapid sensitive and accurate ultra performance liquid chromatography tandem mass spectrometric ( UPLC-MS/MS ) method was developed for the simultaneous determination of 2 , 4 , 6-trinitrophenol, trinitroresorcinate, trinitrophloroglucinol residues in soil. The sample was pretreated by using the modified QuEChERS ( quick, easy, cheap, effective, rigged, and safe ) method that completed the extraction and clean-up steps in one procedure. In this none buffer QuEChERS method, samples were extracted with 1% formic acid ﹢ acetonitrile, cleaned up with primary graphitized carbon black ( GCB) and C18 sorbent, then centrifuged and filtrated before detection. The pretreatment method was simple, rapid and effective and can meet the detection requirements. The UPLC-MS/MS method was performed on Waters Accucore PFP (150 mm× 2. 1 mm, 2. 6 μm) and the column temperature was 30 ℃, the gradient elution with acetonitrile and ammonium acetate as the mobile phase and the flow rate was 0. 3 mL/min. The negative electrospray ionization ( ESI-) source under the multiple reaction monitoring ( MRM ) mode and external standard method were used for quantification. The results showed that the correlation coefficients up to 0. 9942 were obtained across a concentration range of 0. 005-5. 0 mg/L. The limits of detection ( LOD) ranged from 0 . 002 to 0 . 005 mg/kg ( S/N=3 ) . The method was validated with soil samples spiked at three fortification levels (0. 01, 0. 1 and 1 mg/kg) and recoveries were in the range of 79. 3%-94. 8% with relative standard deviations (RSD) of 3. 1%-6. 6%.

A sensitive determination method for sulfur mustard ( HD ) metabolites thiodiglycol ( TDG ) in rabbit urine was established and validated using isotope dilution negative ion chemical ionization ( NICI) gas chromatography-mass spectrometry ( GC-MS ) , in which deuterated thiodiglycol ( TDG-d8 ) was used as internal standard. Two solid-phase extraction ( SPE) steps were established and optimized in order to reduce the interfering backgrounds, one was used to extract thiodiglycol ( TDG ) from urine with self-assemblied Florisil SPE cartridges, another cleaning treatment of the by-products after pentafluorobenzoyl chloride (PFBZ) derivatization. The results showed that the limits of detection quantitation of this method were 0. 1 and 0. 3 μg/L, respectively. The exposure time-response relationship and exposure dose-response relationship of TDG in rabbit urine were studied after rabbit skin exposure to sulfur mustard (HD, 0. 02-0. 15 LD50). The TDG levels in the rabbit urine increased rapidly during the first day after application and then decreased over time for all dosage groups. A secondary release was also noted for the high-dose group, and the duration of high TDG excretion levels was correlated positively with the HD dosage levels. We thus concluded that abnormally high levels of TDG in urine could be used as a clear diagnostic indicator of HD exposure.