雙源電腦斷層臨床肝細胞癌三相檢查影像搭配不同後處理技術之影像品質與劑量分析

Evaluate the clinical HCC image quality and effective dose with different reconstructed techniques scanned by dual-source CT

何奕儒(Yi-Ju Ho)

指導教授 ： 陳拓榮

中山醫學大學/醫學科技學院/生物醫學科學學系碩士班/碩士(2012年)

https://doi.org/10.6834/CSMU.2012.00162

摘要

世界衛生組織於2011年統計資料顯示，亞洲地區肝癌發生率為全球首位，我國行政院衛生署民國九十九年統計資料顯示，國人死因第一位為癌症，其中肝癌占所有癌症中排名第二。在所有肝癌中，肝細胞癌是常見的種類。臨床上診斷受檢者是否患有肝細胞癌，會進行抽血檢驗並取得醫學影像。電腦斷層肝臟三相檢查，是主要用來診斷肝臟疾病的常規檢查，隨著科技的進步，電腦斷層近期發展出雙管球、雙能量掃描技術，以高、低能電壓同時進行掃描，可得到兩組不同能量以及雙能量融合影像，同時增設許多影像重組與後處理技術。本研究主要針對罹患肝細胞癌的病例，使用雙源電腦斷層掃描，進行肝臟三相檢查，並在動脈相以單能量或是雙能量掃描，收集其掃描資訊與醫學影像。在輻射劑量的評估，將劑量長度乘積(DLP)乘上電腦斷層腹部轉換因子，計算三相檢查下的有效劑量。在影像品質的評估，本研究針對動脈相，使用臨床常規的濾波反投影(FBP)以及疊代(IR)法重組影像，並以不同比例融合雙能量影像。客觀性評估：使用手動圈選各器官組織的ROI，量測CT值並計算肝實質與病灶的對比值、雜訊、對比雜訊比與品質因數；主觀性評估：由兩位放射科醫師針對影像雜訊、病灶輪廓的清楚程度、整體影響品質進行評分。另使用影像品質假體，配合臨床上動脈相使用單能量與雙能量的掃描條件，取得不同重組法與後處理技術下的假體影像，進行客觀性的影像品質評估，並與臨床病例影像結果做比較。本研究的目的為：針對臨床上罹患有肝細胞癌的病例，在雙源電腦斷層掃描肝臟三相檢查下，於動脈相使用單能量或是雙能量掃描，以不同後處理技術重組影像，評估其輻射劑量與最佳化的影像品質。

關鍵字

雙源 ； 電腦斷層 ； 肝細胞癌 ； 影像品質

並列摘要

Global cancer statistics for 2011 by world health organization shows the highest liver cancer rates are found in Asia. In Taiwan, the information by department of health, the highest national cause of death at 2010 was cancer, and hepatic cancer was the second cause of death in all cancers. Among primary liver cancers, hepatocellular carcinoma (HCC) is one of the common hepatic cancers. There are several methods to detect HCC. Taking some blood to test the alpha feto protein and observing patient medical image by ultrasound or CT. In clinical, we use CT liver three phase to evaluate liver lesion. A recent development in CT was dual source technology. DSCT can get low energy image, high energy image and dual energy weighted image by use dual energy scanning. In image reconstruction, the current reconstruction method in CT is filtered back projection (FBP), but recently new methods, based on iterative reconstruction (IR) have been introduced. Our study collected HCC patients information and medical images after their underwent dual source CT liver three phase examinations, using single or dual energy scanning at arterial phase. In radiation dose, we multiplied the dose length product by CT conversion factor defined effective dose. In image quality, we reconstructed single and dual energy arterial images by FBP or IR with different kernels. We also reconstructed dual energy weighted image by different weighting factors at dual energy arterial phase. To analyze image quality by objective, we measured organs and tissues CT number by manual ROIs and calculated contrast by liver and lesion, noise, contrast to noise ratio and figure to merit. In subjective image quality, two radiologists recorded image scores by image noise, lesion conspicuity and overall image quality. In addition, we used image quality phantom to undergo single and dual energy arterial phase protocols. Reconstruction by FBP, IR and different weighting factors to analyzed objective image quality for phantom images and compared with patient’s analysis. Our study estimated clinical HCC image quality without increasing radiation dose by different image reconstruction techniques and calculated radiation dose in DSCT liver three phase using single or dual energy at arterial phase.

並列關鍵字

dual source ； CT ； HCC ； image quality

參考文獻

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