Objective To assess the feasibility of low voltage with CARE dose 4D computed tomography pul-monary angiography(CTPA)by using image quality and radiation dosage.Methods 92 patients with clinically sus-pected pulmonary embolism(BMI:20 ~30kg/m2)were randomly divided into two groups(group A:n =46,80kV;groups B:n =46,100kV),the male and female of group A were equal to the number.Image quality score(given blind-ly by two senior radiologists ranged from 1 to 5 points).The CT value and standard deviation(SD)were measured and recorded in common pulmonary artery trunk,the main right pulmonary arteries,right low lobar arteries,and erector muscle of spine,calculated the SNR of ROI.Average CT value,signal noise ratio(SNR),CTDIvol,DLP were com-pared between the two groups.Used the CT dose index(CTDIvol)to compare radiation dosage between group A female and male.Results The agent average CT value and SD in arteries in group A [(510.27 ±115.45)HU,(50.06 ± 11.67)HU respectively]were higher than those in group B[(413.32 ±100.38)HU,(35.12 ±11.94)HU respective-ly],there were significant differences between the two groups(t =10.367,8.892,all P =0.000),but the SNR of ROI was (12.36 ±3.90),which was lower than (14.03 ±4.46)in group B,there was significant difference between the two groups(t =-5.238,P =0.001 ).Image quality score of transverse ection(1mm)in group A was (4.20 ± 0.29),which was lower than (4.91 ±0.36)in group B,there was significant difference(t =-20.23,P =0.000), but there was no significant difference in coronal section(5mm),coronal maximum intensity project(MIP)image and the capability of displaying the pulmonary artery branches(all P >0.05 ).The CTDIvol in group A was (2.03 ± 0.39)mGy,which was greatly lower than (5.04 ±1.02)mGy in group B,there was significant difference (P <0.05);but there was no significant difference between female and male in group A[male:(2.05 ±0.39)mGy;female:(2.01 ±0.38)mGy,t =-0.300,P >0.05].Conclusion Radiation dose can be decreased greatly(above 50%)in 80kV CTPA compared 100kV without compressing obviously the image quality for patients BMI 20 -30kg/m2 ,and no significant difference between the group A(80kV)different gender radiation dosage.

Objective To assess the clinical application value of single-source dual energy CT(SSDE),by measuring the multi-slice CT(MSCT) and single-source dual energy CT(SSDE) lower limb fractures image noise and contrast noise ratio(CNR),comparing the difference in the radiation dosage.Methods 39 cases of lower extremity fractures by clinical diagnosis were included in the study.Preoperation or postoperation the patients underwent MSCT scans,postoperation or postoperative follow-up SSDE CT scans were conducted,two sets of images were achieved.We measured and compared conventional CT group with 130 key energy spectrum group (prior studies showed the elimination of metal artifacts,images,subjective scoring the highest photon energy level) no significant artifacts cancellous bone area,compared the image background noise and contrast noise ratio (CNR),and radiation dosage,using paired sample t-test.Results Two sets of data for the same patient before and after surgery or after review of images,which body mass index (BMI) was negligible.The CTDIvol value of the conventional MSCT was (7.94 ± 1.69) mGy,the dual-energy CT was (7.04 ± 0.97) mGy,with significant difference (t =2.71,P ＜ 0.05) ; The image noise of the conventional MSCT was (44.36 ± 15.66) Hu,the dual-energy CT was (15.04 ± 8.23) Hu,with significant difference (t =15.26,P ＜ 0.05) ; The CNR of the conventional MSCT was (3.96 ± 1.78),the dual-energy CT was (4.62 ± 2.80),with significant difference (t =-2.14,P ＜ 0.05).Conclusion Compared with conventional MSCT,single source dual-energy CT imaging provides improved image CNR,obviously eliminate metal artifacts,to better show the complex structure for lower limb fracture surgery,and reduction in radiation dosage.

Objective To evaluate the advantage of single -source spectrum CT in differentiating of calcifi-cation and tophus.Methods 146 cases of clinical suspected patients with gout pain were scaned by single -source spectrum CT,observed the adjacent to the bone and joint hyperplasia and showing characteristics of gout stone,coun-ted quantity,size and position of the sedimentary tophus.Diagnosed by American rheumatism association standard as the gold standard,computed the sensitivity,specific degrees and accuracy of showing tophus of single -source spec-trum CT and conventional CT,and evaluated the advantage of differentiating adjacent to the bone and joint hyperplasia and gout stone of single -source spectrum CT.Results Diagnosis of gout in 105 cases.Scaned 349 joints,positive in 341 of them,The first plantar toe joint involvement was obvious[118,34.60%(118/341)];The result showed that the sensitivities of the tophus,specific and accurate rate of the conventional CT were 63.80%(67 /105),65.85%(27 /41),64.38%(94 /146),which of single -source spectrum CT were 96.19%(101 /105),87.80%(36 /41), 93.84%(137/146),the differences of sensitivity,specificity and accuracy between the two methods were statistical significance(χ2 =34.42,555,38.34,all P <0.05).Conclusion Single -source spectrum CT in gout stone adjacent to the bone and joint has higher sensitivity and accuracy,specific degree,it is higher than conventional CT and provide a new noninvasive imaging technique for the identification of the peripheral bone and joint of the bone.