臺灣博碩士論文加值系統

隨著醫療設備的改進，雙管球電腦斷層(dual source computed tomography, DSCT)的雙能量技術可以在單次掃描下同時採用高能量和低能量管電壓進行掃描，經由電腦快速運算後得到兩種不同能量的影像，以及重組後雙能量融合的診斷影像，可以更有效的分辨不同器官組織的衰減特性。在雙能量影像後處理技術中，可從有對比劑增強的影像消除病灶內的碘劑，取得虛擬未含對比劑(virtual unenhanced)影像，如此可使病患減少實際未顯影相的掃描，降低接受到的輻射劑量；另外對於體內有植入金屬材質物質的病患，在進行常規檢查時容易產生金屬假影(metal artifact)而影響附近病灶診斷，可使用虛擬單能譜(monoenergy)影像減少或去除金屬假影的影響，同時減少臨床診斷的不確定性。對此本研究觀察虛擬未含對比劑影像的可行性並評估輻射劑量的降幅程度；並觀察假牙和脊椎內固定最合適的單能譜影像和建議使用的材質物質；並搭配臨床常規的濾波反投影法(FBP)和疊代法(IR)之選擇。去除碘劑方面：將模擬二種體型並同時內嵌有不同類型的含碘及未含碘模擬病灶之雙能量假體，經由動脈相雙能量掃描後進行虛擬影像的重組，觀察虛擬影像的可行性，並於Rando假體內填入熱發光劑量計評估肝三相檢查的輻射劑量；去除金屬假影方面：在Rando假體下顎齒列附近分次填放五種臨床常用的假牙材質物質，以及於模擬二種體型的腹部假體內之模擬脊柱中分次填放不鏽鋼或鈦金屬，分別使用頭部和脊椎雙能量掃描後重組單能譜影像。經由客觀性的分析結果，雙能量動脈相產生之虛擬未含對比劑影像，亦會對未含對比劑的器官或病灶有減贅上的影響，因此仍無法取代常規無對比劑增強影像，若未包含實際未顯影相掃描時劑量降幅達24%；虛擬單能譜影像對於假牙或脊椎內固定材質造成之金屬假影能夠有效的去除，使得影像整體價值提高；在影像重建方法方面建議使用IR方法。

With the improvement of medical equipment. Dual-source computed tomography (DSCT) operate by two x-ray tubes with low and high kilovoltage settings at same time, which allows for dual-energy CT (DECT) scanning. This technology can be utilized for tissue characterization based on dual energy image sets. DECT allows the generation of virtual unenhanced images by subtracting iodine from contrast enhanced images which can replacing the true non-contrast scan to reduce the radiation dose. In addition, patients with metallic implants, the detectability of lesions near the implants may affect by the metal artifact. DECT also allows the generation of monoenergetic images to reduce metal artifact. In this study was to assess the feasibility of virtual non-contrast images and to evaluate the potential dose reduction by omitting true non-contrast scan. And to investigate the optimal monoenergy strategy for fixed prosthesis and spinal implants respectively. Moreover, comparing between FBP and IR images to analysis image quality. In the part of virtual unenhanced images, dual energy phantom which contains different kinds of simulation lesions was scanned by arterial protocol. The Rando phantom which was placed TLD inside was scanned by the protocol of liver three phase examination that can obtain the effective dose of liver examination. In the part of reduce metal artifact, Rando phantom and abdomen phantom was placed metallic implants of fix prosthesis and spinal, respectively. Then scanned by the head and spine protocol separately. the dual energy images were loaded into the post-processing software to produce monochromatic images. Based on the result of objective analysis. Virtual non-contrast images cannot represent true non-contrast images, because of limitations in some material subtraction. Dose reduction achieved by omitting the true non-contrast acquisition is 24%. Monoenergetic application can reduce metal artifact and using the optimal keV setting for each implants can improving image quality. The image reconstruction method applied IR images.

目錄 I
圖目錄 IV
表目錄 VI
摘要 IX
Abstract X
謝誌 XI
第一章、前言 1
一、研究動機 1
二、文獻回顧 3
三、研究目的 4
第二章、研究材料 5
一、研究流程圖 5
1. 肝臟動脈相產生虛擬未含對比劑影像 5
2. 去除假牙材質金屬假影 6
3. 去除脊椎內固定材質金屬假影 6
二、電腦斷層儀 7
三、實驗假體 8
1. 類人形腹部假體 8
2. 雙能量假體 9
3. 體環 11
4. Rando假體 11
5. 擬人腹部假體 12
6. 金屬鋼釘植入物 12
第三章、研究方法 14
一、實驗掃描參數 14
1. 肝臟動脈相產生虛擬未含對比劑影像 14
2. 去除假牙材質金屬假影 15
3. 去除脊椎內固定材質金屬假影 16
二、後處理軟體 18
1. Liver VNC application 18
2. Monoenergy application 19
三、影像圈選方式及影像品質分析方法 19
1. 影像分析軟體 19
2. 影像圈選步驟 20
3. 肝臟動脈相產生虛擬未含對比劑影像 20
4. 去除假牙材質金屬假影 22
5. 去除脊椎內固定材質金屬假影 23
四、輻射劑量評估 24
1. 肝臟動脈相產生虛擬未含對比劑影像 24
第四章、研究結果 26
一、影像品質分析 26
1. 肝臟動脈相產生虛擬未含對比劑影像 26
2. 去除假牙材質金屬假影 33
3. 去除脊椎內固定金屬假影 40
二、輻射劑量評估 51
1. 肝臟動脈相產生虛擬未含對比劑影像 51
第五章、分析與討論 52
一、影像品質分析 52
1. 肝臟動脈相產生虛擬未含對比劑影像 52
2. 去除假牙材質金屬假影 56
3. 去除脊椎內固定材質金屬假影 61
二、輻射劑量評估 62
1. 肝臟動脈相產生虛擬未含對比劑影像 62
三、研究限制 63
第六章、結論 65
參考文獻 66
附件 68

1.Gao Y, Quinn B, Mahmood U, Long D, Erdi Y, St Germain J, Pandit-Taskar N, Xu XG, Bolch WE, Dauer LT, A comparison of pediatric and adult CT organ dose estimation methods. BMC Medical Imaging, 2017, 17(1): 28.
2.Yeh DM, Tsai HY, Tyan YS, Chang YC, Pan LK, Chen TR, The population effective dose of medical computed tomography examinations in Taiwan for 2013. PLos One, 2016, 11(10): e0165526.
3.Graser A, Johnson TR, Chandarana H, Macari M, Dual energy CT: preliminary observations and potential clinical applications in the abdomen. Eur Radiol, 2009, 19(1): 13-23.
4.Toepker M, Moritz T, Krauss B, Weber M, Euller G, Mang T, Wolf F, Herold CJ, Ringl H, Virtual non-contrast in second-generation, dual-energy computed tomography: reliability of attenuation values. Eur J Radiol, 2012, 81(3): e398-405.
5.Marin D, Boll DT, Mileto A, Nelson RC, State of the art: dual-energy CT of the abdomen. Radiology, 2014, 271(2): 327-342.
6.Rutherford RA, Pullan BR, Isherwood I, X-ray energies for effective atomic number determination. Neuroradiology, 1976, 11(1): 23-28.
7.Johnson TR, Krauss B, Sedlmair M, Grasruck M, Bruder H, Morhard D, Fink C, Weckbach S, Lenhard M, Schmidt B, Flohr T, Reiser MF, Becker CR, Material differentiation by dual energy CT: initial experience. Eur Radiol, 2007, 17(6): 1510–1517.
8.Flohr TG, McCollough CH, Bruder H, Petersilka M, Gruber K, Suss C, Grasruck M, Stierstorfer K, Krauss B, Raupach R, Primak AN, Kuttner A, Achenbach S, Becker C, Kopp A, Ohnesorge BM, First performance evaluation of a dual-source CT (DSCT) system. Eur Radiol, 2016, 16(2): 256–268.
9.Euler A, Parakh A, Falkowski AL, Manneck S, Dashti D, Krauss B, Szucs-Farkas Z, Schindera ST, Initial Results of a Single-Source Dual-Energy Computed Tomography Technique Using a Split-Filter: Assessment of Image Quality, Radiation Dose, and Accuracy of Dual-Energy Applications in an In Vitro and In Vivo Study. Invest Radiol, 2016, 51(8): 491-498.
10.Barrett T, Bowden DJ, Shaida N, Godfrey EM, Taylor A, Lomas DJ, Shaw AS, Virtual unenhanced second generation dual-source CT of the liver: is it time to discard the conventional unenhanced phase? Eur J Radiol, 2012, 81(7): 1438-1445.
11.Graser A, Johnson TR, Hecht EM, Becker CR, Leidecker C, Staehler M, Stief CG, Hildebrandt H, Godoy MC, Finn ME, Stepansky F, Reiser MF, Macari M. Dual-energy CT in patients suspected of having renal masses: can virtual nonenhanced images replace true nonenhanced images? Radiology, 2009, 252(2):433-440.
12.De Cecco CN, Darnell A, Macías N, Ayuso JR, Rodríguez S, Rimola J, Pagés M, García-Criado A, Rengo M, Laghi A, Ayuso C, Virtual unenhanced images of the abdomen with second-generation dual-source dual-energy computed tomography: image quality and liver lesion detection. Invest Radiol, 2013, 48(1): 1-9.
13.Shi L, Yan F, Pan Z, Liu B, Liu H, Wang B, Zhang H, Yu Y, Stomach virtual non-enhanced CT with second-generation, dual-energy CT: a preliminary study. PLoS One, 2014, 9(11): e112295.
14.衛生福利部－民國105年度死因統計，行政院衛生福利部：中華民國(ROC)。
15.Guggenberger R, Winklhofer S, Osterhoff G, Wanner GA, Fortunati M, Andreisek G, Alkadhi H, Stolzmann P, Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels. Eur Radiol, 2012, 22(11): 2357-2364.
16.Cha J, Kim HJ, Kim ST, Kim YK, Kim HY, Park GM, Dual-energy CT with virtual monochromatic images and metal artifact reduction software for reducing metallic dental artifacts. Acta Radiol, 2017, 0(0): 1-8.
17.Geyer LL, Schoepf UJ, Meinel FG, Nance JW Jr, Bastarrika G, Leipsic JA, Paul NS, Rengo M, Laghi A, De Cecco CN, State of the Art: Iterative CT Reconstruction Techniques. Radiology, 2015, 276(2): 339-357.
18.Li JH, Du YM, Huang HM, Accuracy of dual-energy computed tomography for the quantification of iodine in a soft tissue-mimicking phantom. J Appl Clin Med Phys, 2015, 16(5): 418-426.