- 學位論文
電腦斷層偵檢器陣列於不同切面厚度影像品質之差異
The Difference of Computed Tomography Image Quality by Using Different Detector Arrays and Slice Thickness
摘要
研究目的 本研究使用不同偵檢器厚度掃描假體後，重組8種不同切面厚度，分析兩組偵檢器SNR、CNR以及影像目測評分，探討不同偵檢器厚度影像品質的差異。 材料與方法 偵檢器厚度分別為0.5 mm以及1 mm，掃描能量為120 kVp，掃描RMI-467人體等效組織假體，利用假體內四種不同密度組織(分別為皮質骨、肺、腦以及脂肪)進行掃描後，重組為1 mm、2 mm、3 mm、4 mm、5 mm、7 mm、8 mm及10 mm等8種不同切面厚度。 利用影像分析軟體分析2種偵檢器厚度以及8種不同切面厚度的SNR與CNR。並透過兩位放射師對影像進行視覺評分，探討在以不改變劑量的條件下對於影像品質最佳的掃描參數。 結果 實驗結果顯示使用偵檢器厚度0.5 mm對於皮質骨和腦部重組切面厚度4 mm以及對肺部重組切面厚度7 mm、8 mm及10 mm的SNR值比偵檢器厚度1 mm的SNR值高，在其他重組切面則都是偵檢器厚度1 mm的SNR值比偵檢器厚度0.5 mm的SNR值高；偵檢器厚度1 mm在所有重組切面下的CNR都比偵檢器厚度0.5 mm高，目測評分偵檢器厚度0.5 mm只有在切面厚度3 mm的皮質骨假體、切面厚度7 mm皮質骨假體及脂肪假體的分數比偵檢器厚度1 mm高，在切面厚度5 mm時兩組偵檢器的分數是最接近的。 結論 在不改變劑量及重建濾片的情況下，使用不同偵檢器厚度對於電腦斷層影像品質有一定的影響。
並列摘要
Purpose In this study, scanning the phantom with different detector thicknesses was performed to analyze the SNR, CNR and visual score of the different detector arrays with 8 different slice thickness reconstructed to compare the difference of image quality. Materials and methods The detector thicknesses were 0.5 mm and 1 mm, and the scanning energy is 120 kVp to scan the RMI-467 tissue characterization phantom. Scanning four kinds of tissues with different densities(cortical bone, lung, brain and adipose), reconstructed slice thickness to 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm and 10 mm. Using DICOM Viewer to analyze the SNR and CNR of 2 detector thicknesses with 8 different slice thicknesses. The images were reviewed and scored by two radiological technologist to explore the best scan parameters without changing the dose for image quality. Results The results showed that the SNR values of the detector thickness 0.5 mm for the cortical bone and brain reconstruction thickness 4 mm and 7 mm, 8 mm and 10 mm of the lung phantom are higher than the SNR value of the detector thickness 1 mm, in other reconstruction thickness, the SNR of detector thickness 1 mm is higher than detector thickness 0.5 mm; visual score of detector thickness 0.5 mm only higher in the cortical bone phantom with thickness of 3 mm, cortical bone phantom and adipose phantom with thickness of 7 mm, the scores were higher than the detector thickness of 1 mm. The scores of the two sets of detectors are closest at thickness of 5 mm. Conclusion If not change the dose and reconstruction filter, use different detector thicknesses had a certain impact on the image quality of computed tomography.