| Objectives 1 To discuss the possibility that the contrast agent with low dosage and low concentration can be used for injection in the process of S.M.A CTA on 256 MSCT. 2 To discuss the possibility that the low pipe combined with automatic voltage current technology can be used in reducing the radiation dosage in the process of S.M.A CTA on 256 MSCT.Methods 1 Selecting 120 patients who has been examined by S.M.A CTA and dividing them into 2 groups randomly,one is routine group and the other is double-low group,each group has 60 patients.The patients in routine group are injected with contrast agent:iopromide(370 mg I/m L)whose injection dosage is calculated by the weight( 1.0m L/kg);while the patients in double-low group are injected with contrast agent:ioversol(320 mg I/m L)whose injection dosage is calculated by a formula that weight×1.0m L/kg-10 m L.Then,comparing the relationship of basic information among the patients in these two different groups from age,gender,weight and many other aspects. Next,measuring the CT value in images of these two groups separately both at origin of superior mesenteric artery and L2 vertebral horizontal position.At last,calculating the total injection dosage of contrast agent and iodine agent in these two groups and meanwhile recording the scores of image quality in these two groups. 2 Selecting 100 patients who has been examined by S.M.A CTA and dividing them into 2 groups randomly,one is routine group and the other is low-dose group,each group has 50 patients. Scanning parameters in routine group are:the value of tube voltage is 120 k V,the value of tube current is 250 m As;Scanning parameters in low-dose group are:the value of tube voltage 100 k V,the value of tube current is between 100 m As~400m As.The patients in routine group are injected with contrast agent:iopromide( 370 mg I/m L) whose injection dosage is calculated by weight( 1.0m L/kg).Comparing the relationship of basic information among the patients in these two different groups from age,gender and weight and many other aspects.Then,measuring the CT value in these two images separately both at origin of superior mesenteric artery and L2 vertebral horizontal position.At last,calculating the value of patients’ DLP and ED in these two groups,meanwhile, recording the scores of image quality of these two groups.Collating the above data through Excel 2003 database and analyzing them through statistical software SPSS14.0.The measurement data are showed as the following form:average value± standard deviation.The independent sample ‘t’ text is used for the patients in routine group and double-low group by the first method which includes the test of age and weight,the superior mesenteric artery CT value at different places,the injection of contrast agent and the total quantity of iodine agent.The chi-square test is used for the scores of image quality and comparing the gender of the patients in these two groups.It has statistical significance when P<0.05.The independent sample ‘t’ text is used for the patients in routine group and low-dose group by the second method which includes the test of the age and weight,the superior mesenteric artery CT value at different places and the values of DLP and ED.The chi-square test is used for the scores of image quality and comparing the gender of the patients in these two groups.It has statistical significance when P<0.05.Results 1 The differences on age, weight, gender and any other basic data among the patients in routine group and double-low group have no statistical significance(P>0.05).The CT value at origin of superior mesenteric artery and L2 vertebral horizontal position in routine group are:363.0±7.52 HU and 350.78±7.02HU; the CT value at origin of superior mesenteric artery and L2 vertebral horizontal position in double-low group are : 298.30±6.90 HU and 285.46±5.09HU; these differences have statistical significance(P<0.05).The dosage of contrast agent in routine group and double-low group are: 68.07±9.59 m L and 57.09±9.41 m L,these differences have statistical significance(P<0.05);the injection dosage of iodine in routine group and double-low group are : 25.18±3.55 g and 18.27±3.01g;these differences have statistical significance(P<0.05). The difference of image quality between routine group and double-low group has no statistical significance(P>0.05)2 The differences on age,weight,gender and any other basic data among the patients in routine group and low-dose group have no statistical significance(P>0.05).The CT value at origin of superior mesenteric artery and L2 vertebral horizontal position in routine group are:359.69±7.71 HU and 356.51±6.23HU;the CT value at origin of superior mesenteric artery and L2 vertebral horizontal position in low-dose group are:2357.22±7.56 HU and 355.90±8.72HU;these differences have statistical significance(P<0.05).The difference of image quality between routine group and lowdose group has no statistical significance(P>0.05).The values of DLF and ED in routine group are:294.58±20.42 m Gy.cm and 4.42±0.31 m Sv;the values of DLF and ED in low-dose group are :255.74±45.00 m Gy.cm and 3.83±0.68 m Sv;these differences have statistical significance(P<0.05).Conclusions 1 It is viable to use the low concentration low dosage contrast agent for injection in the process of S.M.A CTA. This method can get satisfied image to meet the needs of the clinical diagnosis,decrease the iodine injection dosage and reduce the nephrotoxicity.2 It is viable to apply the technology that one combines low pipe with automatic voltage current for scanning in the process of S.M.A CTA.This method can get satisfied image to meet the needs of the clinical diagnosis and decrease radiation dosage of patients and then ensure the health of the patients. |
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