| Objective: Children with X-ray dose per unit volume of imaging are much higher than those of adults,and children are more sensitive to X-ray radiation than adults.Under the same radiation dose,the damage to children is much greater than that of adults,It is a very meaningful task to reduce the dose of X-ray in children’s imaging.The purpose of this experiment is to reduce the number of children affected by the requirement of image quality diagnosis Radiation dose,the study produces a minimum radiation dose and meets the diagnostic requirements of the scanning conditions.Method: This experiment is carried out under dual source CT.The device uses Siemens Definition Flash dual source CT and selects Flash Spiral mode for chest scan.Check to open CARE Dose 4D technology.The model is modeled as 76-414-4150,by the Shanghai Ziyuan trading company distribution of the United States FLUKE Fluke production of the body.According to the different voltage of the tube,60 kV,80kV,100 kV,120kV each group,the tube current is set to automatic milliseconds,the pitch is 5.0,the layer thickness is 5.0mm,and the reconstructed image is SAFIRE3 iterative technique.The body model was placed in accordance with the standard position of the chest scan,and 50 times under each condition,each time the body thickness was adjusted to simulate children of different sizes.Transfer the scan results to the workstation for further processing.Image analysis:(1)image reconstruction and objective evaluation criteria: AW4.6 workstation(GE HeahhCare,USA)to reconstruct the image.Applying the signal-to-noise ratio to evaluate the image objectively,the specific method of operation is that the center position of the model is 3.0mm 2,and the SD value and CT value of this area are measured and recorded.The image signal-to-noise ratio(SNR)is calculated as: SNR = CT value / noise SD of the corresponding ROI.(2)subjective evaluation criteria: by the two senior titles above the senior imaging physician based on clinical experience to evaluate the image quality score.The image quality from poor to excellent is divided into 1 to 5 points,the specific criteria: 1 point,the normal organizational structure is unclear,the edge blurred,completely unable to distinguish between organizational structure;2 points,the organizational structure is blurred;3 points,the edge of the organizational structure is relatively vague,there is a little artifacts exist,but the normal structure of the show is acceptable;4 points,the edge of the organizational structure of some blurred,but no artifacts The existence of a clear display of the relationship between the structure;5 points,the edge clear,no artifacts.SPSS22.0 statistical software for processing,descriptive data first correlation analysis,surface radiation dose were paired t test.The evaluation of subjective quality of images is divided into general clear group and general and difference group.Statistical analysis is carried out by rank sum test.The test standard is set to a = 0.05.Results: Statistical analysis found that the effective dose(ED)value decreased with the decrease of kV.120 kV was 3.21 ± 0.19 msv,100 kV was 1.92 ± 0.14 msv,80 kV was 0.75 ± 0.07 msv,and 60 k V was 0.23 ± 0.02 msv.There was a significant difference between the two groups(P = 0.000)There was no significant difference between the other groups(P = 0.000)and the other groups.There was no significant difference between the other groups.80 kV-120 kV(P = 0.612),80 kV-100 kV(P = 0.609),100 kV-120 kV(P = 0.997)(Table 6).The SNR values of the four groups decreased with the decrease of k V,and there was no statistically significant difference between the two groups(P = 0.344)between the 100 kV and 120 kV statistically Differences(P = 0.000)(Table 7).(Detailed data and statistical analysis see table).Therefore,80 kV is ideal in terms of minimizing the principle of low-dose radiation protection(ALARA),which can meet the diagnostic requirements and minimize the radiation dose.Conclusion:1 image quality decreases with the decrease of kV value.2 the radiation dose decreases as kV falls.3 80 kV The following image quality can not meet the diagnostic requirements.4 According to the principle of minimizing the use of radiation protection as low as possible(80),80 kV is ideal,both to meet the diagnostic requirements,but also to minimize the radiation dose,by reducing the kilovolt,automatic Anne and other traditional aspects of the combination with the latest iterative algorithm to achieve the reduction in kilovolt at the same time,can meet the diagnostic requirements of the image quality requirements.It is proved that the iterative algorithm and the automatic millisecond technique can achieve the image quality satisfying the diagnostic requirement at the same time when the radiation dose is greatly reduced. |
PDF Full Text Request