利用田口最佳化評量心導管攝影之影像品質中的最低可偵測極限

Optimizing the Minimum Detectable Difference (MDD) of Cardiac X-ray Imaging Quality Using the Taguchi Analysis and a Precise Line Pair Gauge

陳科霖(KE-LIN CHEN)

指導教授 ： 潘榕光

中臺科技大學/健康科學院/醫學影像暨放射科學系暨研究所/碩士(2019年)

摘要

心導管檢查是利用特製不透光導管經由大腿股動脈或手腕的週邊動脈將導管送達心臟的冠狀動脈開口處，然後注射顯影劑，再利用X光透視來檢視心臟血管血流狀況、病變位置及嚴重程度。心導管檢查是目前診斷冠狀動脈疾病最準確的方法。
在本次研究中，將利用田口分析方法及線對塊規假體與固態水假體進行心導管X-ray的照射，來評量各個參數設定的最佳化條件。實驗使用田口L8直交表進行8組不同參數條件的照射，設定四個可變因子，分別為(A)焦點大小(Focus)；(B)管電壓(kVp)；(C)管電流與時間乘積(mAs)；(D)射源至影像接受器的距離(SID)；每個可變因子均設定兩個(低和高)水準。通過X-ray照射後得到影像，再由三名資心臟科放射醫師依雙盲法進行打分評定。實驗採用高對比、低噪聲、高精度的標準對線對假體給出評分。然後對該評分利用修訂後的學生t檢定進行分析，推導出MDD來表示X射線圖像的空間解析度。在整個實驗中，確定了最佳解析度組合，並進行臨床驗證。
結果顯示，臨床設定、第7組(在八標組合中最高評分)和最佳化設定所計算得出的最低可偵測極限分別為0.183、0.167和0.157mm，對比與線對假體所對應的刻度(LP/mm)分別為2.7、3.1和3.2LP/mm。
所以在這次實驗可以確認，田口分析方法是研究心導管X-ray最低可偵測極限解析度的較佳的方法，並且經由t檢定分析，可以有效提高影像解析度。

關鍵字

田口分析方法 ； t檢定 ； 最低可偵測極限

並列摘要

Objective: To optimize the minimum detectable difference (MDD) of a cardiac X-ray imaging system using the Taguchi L8(27) analysis and a precise line pair gauge.
Methods: The optimal combination of the four critical factors of the cardiac X-ray imaging system, namely X-ray focus, kilovoltage (kVp), milliamper-seconds (mAs), and source image distance (SID), providing the minimum detectable difference (MDD) was calculated via the Taguchi analysis and experimentally verified. Two (low and high) levels were assigned for each factor, and eight combinations of four factors were used to acquire instant X-ray images using an NDT commercial line pair gauge (with a gauge length of 64 mm and a width of 3.5 mm). The latter had five lines and was split gradually from top to bottom for the inspection of X-ray images, which quality was ranked by three well-trained radiologists according to the double-blind criterion. The ranking grade was given by sharp contrast, low noise, and precision to distinguish the line pair. Accordingly, the MDD was derived to represent the spatial resolution of instant X-ray images by the revised Student’s t-test analysis. The optimal combination of factors was experimentally identified and clinically verified in the follow-up inspections.
Results: For the conventional setting, Group No.7 (which obtained the highest grade among eight groups), and the optimal setting, the obtained MDD values were 0.183, 0.167, and 0.157 mm, , respectively, while the line pair (line pair/mm) interpolated from the gauge scale amounted to 2.7, 3.1, and 3.2 LP/mm, respectively.
Conclusion: The Taguchi L8 analysis was proved to be instrumental in optimizing the cardiac X-ray imaging system MDD and is recommended to be used jointly with the revised Student’s t-test analysis for improving the spatial resolution of instant X-ray images.

並列關鍵字

Taguchi analysis ； t-test ； minimum detectable difference

參考文獻

參考文獻

[1]衛生福利部統計處，歷年死因統計

https://dep.mohw.gov.tw/DOS/lp-3960-113.html

[2]衛生福利部國民健康署-認識冠心病

https://www.hpa.gov.tw/Pages/Detail.aspx?nodeid=632&pid=1188#