- 學位論文
評估單能量和雙能量CT掃描影像特徵與ACR假體擺放位置的相關性
Correlations between ACR Phantom Positioning and Image Characteristics of Single Energy CT and Dual Energy CT
摘要
雙能量電腦斷層掃描儀(Dual Energy Computed Tomography, DECT)於近十年迅速發展，臨床多應用於腦部與心血管造影、血流灌注造影、頸部動脈、小兒之免鎮靜超快速造影與區別不同的高亮度物質:包括軟硬血管內壁斑塊，對比劑、結石及痛風的鈣化物質。 為了確保國人接受電腦斷層掃描檢查，有一定水平以上的影像品質，原能會的規範要求年度電腦斷層掃描儀品保測試的標準，其中美國放射學院的電腦斷層認證假體(American College of Radiography Phantom, ACR Phantom)為X光電腦斷層掃描儀品保測試中最重要的測試工具之一。目前的規範是針對單能量的電腦斷層掃描儀(Single Energy CT, SECT)為檢測的目標。本實驗比較單能量與雙能量腦斷層使用相同掃描條件執行ACR 假體掃描並重組影像，同時改變假體位置，分別探討分析ACR假體中Module1、Module2、Module3及Module4影像的變化情形。 結果發現單能CT在各模組(Module)包括CT數、低對比解析度、距離準確度或高對比解析度的量測值差異均較小，且均在原子能委員會規範範圍之內，其結果是較可信的。然而，雙能CT除模組3之外，其他三個模組多數量測值差異很大，但各模組量測均發現某些特定條件之量測值的差異與單能CT相近。
並列摘要
Dual energy computed tomography (DECT) has grown rapidly in the last decade. It is widely applied in clinical applications, commonly on brain and cardiovascular angiography, blood perfusion angiography, carotid artery, pediatric non-sedative ultra-fast CT scan and discriminates different high-brightness substances, including soft and hard vascular wall plaques, contrast agents and calculus and gout of calcified substances. In order to ensure the image quality of computed tomography examination in our country. Annual quality assurance (QA) test of computed tomography scanner should be carried out to guarantee the system status, which is required and specified by Atomic Energy Council (AEC). One of the most important X-ray computed tomography QA test tools is ACR Phantom which is a phantom certified by American College of Radiography Phantom. The current definition form AEC is only for single-energy computer tomography. The present specification demands on single energy CT (SECT) scanner. In this study, we compared the SECT and DECT using the same scanning parameters to perform scanning on ACR phantom and to reconstruct CT images. In the meantime, it was proposed to investigate the changes of image features on the ACR Phantom’s Module1, Module2, Module3 and Module4 by shifting phantom’s position individually. The results showed that the measurements of SECT scan were more reliable because smaller deviations for all of the modules’ measurements (CT number, low contrast resolution, in-plane distance accuracy or high contrast resolution) which were within the range of Atomic Energy Council (AEC) specification. However, excluding the measurement of module 3, the measurements of the other three modules had large variations by DECT scan. And there had similar variations with SECT measurements for all three measurements under some specific conditions using DECT scan.