| Part I: Study on the difference of radiation dose and image quality under different scanning parametersObjective: To study whether there are differences in radiation dose and image quality under different tube voltage and tube current scanning parameters.Materials and methods: We used a standard life-size male chest phantom,and 12 smooth spherical artificial lung nodules with diameters of 3mm,5mm,8mm,and 10 mm,and which CT attenuation values of-800 HU,-630 HU,and +100 HU.GE Revolution CT scanner was used to scan the phantom nodules with different tube voltage(KV)and tube current(m A)combined scanning schemes.The four tube voltages were: 70 KV,80KV,100 KV,120KV.The 10 tube currents were: 20 m A,40 m A,60 m A,80 m A,100 m A,120 m A,140 m A,160 m A,180 m A,200 m A.We analyzed the effective radiation dose(ED),image quality.Results: There was statistically significant differences in effective radiation doses between different tube voltages(P <0.05).As the tube voltage current increase,the ED increases.The correlation between different voltages and image subjective quality scores was poor(r = 0.17).The relationship between different tube currents and the subjective quality score of the image is still acceptable(r = 0.54).As the tube current value increases,the subjective score of the image gradually increases.There were statistical differences in the NI,SNR,and CNR of the images between different tube voltages and different tube currents(P<0.05).As the tube voltage and tube current increase,the image NI decreases,and the SNR and CNR increase.Part 2: Study on the accuracy of measuring the volume of solid nodules by different softwareObjective: To study whether there are differences in phantom nodules segmented by different computer software and whether it affects the accuracy of phantom nodule volume measurement,and compared the accuracy of nodule volume measurement with different measurement methods.Materials and methods: We used a standard life-sized male chest phantom and 4 smooth artificial spherical solid lung nodules with diameters of 3mm,5mm,8mm,and 10 mm,and volumes of 14.1mm3,65mm3,268mm3,and 523mm3,respectively.The images were reconstructed using Lung,Stand and Bone algorithms.The measurement software was GE AW 4.7 workstation Lung VCAR software and SIMENS Sygno.VIA workstation Oncology software.We measured manually the diameter of the nodule and calculated the volume of the nodule,and measured the volume of the nodule with GE AW 4.7 Lung VCAR software(Stand and Bone reconstruction)and SIMENS Sygno.VIA Oncology software(Lung algorithm reconstruction).We calculated the relative error of nodule volume measurement and evaluated its accuracy.According to the software segmentation nodule level(1-4 points),the two software segmentation nodules were compared,and compared the accuracy of nodule volume measurement with different measurement methods.Results: The relative errors of nodule volume of Manual measurement,Lung VCAR software(Stand algorithm reconstruction)method,Lung VCAR software(Bone algorithm reconstruction)method,Oncology software measurement(before correction)method,and Oncology software measurement(after correction)method were:-0.156 ± 0.11,0.003 ± 0.11,0.003 ± 0.12,0.080 ± 0.13,0.0006 ± 0.02.Nodule volume was measured by Lung VCAR software,and the volume measured by Oncology software(after correction)was no statistically different from the standard value(P >0.05).The relative errors measured by different segmentation scoring(1-4 points)nodule software were: 0.0915 ± 0.099,0.0431 ± 0.127,0.008 ± 1.382,0.003 ± 0.726.As the score increases,the accuracy with which the software measures the nodule increases.The nodule segmentation ability scores of Lung VCAR software(Stand algorithm reconstruction)method,Lung VCAR software(Bone algorithm reconstruction)method,and Oncology software measurement(pre-correction)method were: 2.688,2.781,2.269.Comparison of three software measurement image segmentation capabilities were: Lung VCAR software(Bone algorithm reconstruction)method> Lung VCAR(Stand algorithm reconstruction)software method> Oncology software measurement(before correction)method.Part III: Study on the accuracy and difference of nodule volume measurement between different scanning parametersObjective: To study whether different tube voltage and tube current scanning parameters affect the accuracy of phantom nodule volume measurement,and whether there are differences in phantom nodule volume measurement between different tube voltages and different tube currents.Materials and methods: A standard life-size male chest phantom and a smooth 8mm artificial spherical solid lung nodule were used.GE Revolution CT scanner was used to scan the phantom nodules with different tube voltage(KV)and tube current(m A)combined scanning schemes.The four tube voltages were: 70 KV,80KV,100 KV,120KV.The 10 kinds of tube currents were: 20 m A,40 m A,60 m A,80 m A,100 m A,120 m A,140 m A,160 m A,180 m A,200 m A,and the Stand algorithm is used to reconstruct the image.GE AW 4.7 Lung VCAR software was used to measure the nodular volume value,and the relative error of nodular volume measurement was calculated.We evaluated the accuracy of software to measure phantom nodules between different tube voltages and tube currents and the difference in volume values of software to measure phantom nodules between different tube voltages and tube currents.Results: There was no statistical difference between the nodule volume measured with the four tube voltages and the standard values and 10 tube current scanning parameters and the standard values(P> 0.05).As the tube voltage increases,the nodular volume value increases.There were statistical differences in the nodule measurement volume among 4 different tube voltages(P <0.05).There were statistical differences between 70 KV and 80 KV,100KV,120KV(P <0.05).With the increase of tube current,the measurement value of nodule volume increased,but the difference was not significant.There was no statistical difference in nodule volume between 10 tube currents(P> 0.05).Conclusion1.There are statistical differences in effective radiation doses between different tube voltages and different tube currents.As the tube voltage and tube current increase,the ED increases.2.There is a certain correlation between different tube currents and the subjective quality score of the image.As the tube current increases,the subjective score of the image gradually increases;but the correlation between different tube voltages and the subjective quality of the image is poor.3.As the tube voltage and tube current increase,the image NI decreases,and the image SNR and CNR increase.4.The volumetric accuracy of phantom nodules measured by software is better than manual measurement methods.Among them,the nodule measurement accuracy of Lung VCAR software is the highest,and the nodule segmented by Oncology software is highly accurate after subsequent editing.5.The accuracy of nodule measurement by different software is positively related to the ability of the software to segment the nodules.6.Changing tube voltage and tube current does not affect the accuracy of 8mm solid nodule measurement.7.As the tube voltage increases,the 8mm solid nodule volume measured by the software increases,and 70 KV is less than the> 70 KV tube voltage nodule measurement volume.8.Changing the tube current does not affect the software to measure the solid nodule volume value of 8mm. |
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