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研究生:盧昊遠
研究生(外文):LU, HAO-YUAN
論文名稱:以疊代影像重建法在0.5 mm切片厚度 進行冠狀動脈鈣化掃描之HU閾值最佳化
論文名稱(外文):Optimization of HU threshold for coronary artery calcium scansreconstructed at 0.5-mm slice thicknessusing iterative reconstruction
指導教授:楊晴晴
指導教授(外文):YANG, CHING-CHING
口試委員:陳拓榮吳東信楊晴晴
口試委員(外文):CHEN, TOU-RONGWU, TUNG-HSINYANG, CHING-CHING
口試日期:2020-06-12
學位類別:碩士
校院名稱:慈濟科技大學
系所名稱:放射醫學科學研究所
學門:醫藥衛生學門
學類:醫學技術及檢驗學類
論文種類:學術論文
論文出版年:2020
畢業學年度:108
語文別:中文
論文頁數:82
中文關鍵詞:低劑量電腦斷層冠狀動脈鈣化分析自動曝射控制疊代重建法
外文關鍵詞:Agatston scorecoronary artery calcificationiterative reconstructionprotocol optimization
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目的:本研究使用多變異數迴歸法以分析0.5 mm切片厚度與IR重建下,不同密度鈣化下管電壓、SD值、體型與CT值閾值對於冠狀動脈鈣化分數(CACS)之影響。迴歸結果用於計算最佳化CT值閾值,以校正Agatston score,使其獲得與臨床参數一致之得分。
方法:本研究使用3種體型的胸部模型。掃描包括1組在3 mm切片厚度以FBP重建之臨床參數,12組在0.5 mm切片厚度以IR重建之實驗參數(三種 kVp設置* 四種 SD值設置)。設置三個CT值閾值(130、150和170 HU)用於鈣化之定量,多變異數迴歸法用於分析0.5 mm切片厚度與IR重建下,不同密度鈣化下管電壓、SD值、體型與CT值閾值對Agatston score的影響。
結果:各迴歸結果R2皆大於0.80。為確保120 kVp、100 kVp和80 kVp之CAC掃描在0.5 mm切片厚度下使用IR重建對3種不同體型分析CACS之準確性,我們根據迴歸模型以SD值為函數計算最佳化CT值閾值。我們的結果表明,應根據掃描條件調整最佳化CT值閾值;針對24.5 cm的體形而言,SD值設置為55進行的120-kVp CAC掃描,使用130 HU是合適的閾值。
結論:本研究針對使用0.5 mm切片厚度IR重建之CAC掃描提出最佳化HU閾值,透過校正可獲得與臨床參數ㄧ致之Agatston score,研究表明了透過減少切片厚度以降低部分體積效應,並同時保持合理抑低的低劑量高精確度CACS之可行性。

Purpose: This work investigated the simultaneous influence of tube voltage, tube current, body size and HU threshold on calcium scoring reconstructed at 0.5-mm slice thickness using iterative reconstruction (IR) through multivariate analysis. Regression results were used to optimize the HU threshold to calibrate the resulting Agatston scores to be consistent with those obtained from the conventional protocol.

Methods: A thorax phantom set simulating 3 different body sizes was used in this study. A total of 14 coronary artery calcium (CAC) protocols were studied, including 1 conventional protocol reconstructed at 3-mm slice thickness, 1 FBP protocol and 12 statistical IR protocols (3 kVp values*4 SD values) reconstructed at 0.5-mm slice thickness. Three HU thresholds were applied for calcium identification, including 130, 150 and 170 HU. A multiple linear regression method was used to analyze the impact of kVp, SD, body size, HU threshold on the Agatston scores of 3 calcification densities for IR-reconstructed CAC scans acquired with 0.5-mm slice thickness.

Results: Each regression relationship has R2 larger than 0.80, indicating a good fit to the data. Based on the regression models, the HU thresholds as a function of SD estimated to ensure the quantification accuracy of calcium scores for 120-, 100- and 80-kVp CAC scans reconstructed at 0.5-mm slice thickness using IR for 3 different body sizes were proposed. Our results indicate that the HU threshold should be adjusted according to the imaging condition, while a 130-HU threshold is appropriate for 120-kVp CAC scans acquired with SD = 55 for body size of 24.5 cm.

Conclusion: The optimized HU thresholds were proposed for CAC scans reconstructed at 0.5-mm slice thickness using IR. Our study results may provide a potential strategy to improve the reliability of calcium scoring by reducing partial volume effect while keeping radiation dose as low as reasonably achievable.

中文摘要 I
Abstract II
致謝 III
目錄 IV
圖目錄 VI
第一章 緒論 1
1.1前言 1
1.2冠狀動脈鈣化機轉 2
1.3電腦斷層發展 4
1.4冠狀動脈鈣化掃描 7
1.5管電流調控系統 10
1.6電腦斷層影像重建技術 14
1.7目的 16
第二章 文獻回顧 17
2.1切片厚度對CACS之影響 17
2.2影像雜訊對CACS之影響 20
2.3減少管電壓對於輻射劑量及CACS之影響 32
2.4高精確性低劑量CAC掃描之可行性 34
2.5實驗構想 38
第三章 材料與方法 40
3.1胸腔假體 40
3.2冠狀動脈鈣化掃描 43
3.3影像分析 45
3.3.1影像品質 45
3.3.2直方圖與高斯擬合 49
3.3.3鈣化面積量測 51
3.4多變異數迴歸分析 52
第四章 結果與討論 54
4.1 各因子對於影像及鈣化分數之影響 54
第五章 結論 76
第六章 參考文獻 77


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