- 學位論文
雷射都卜勒偵測血管血流的可行性分析
The feasibility of Using Laser Doppler Flowmeter to Detect Blood Flow in Vessel
摘要
體外透析的洗腎患者的動靜脈廔管極容易發生栓塞，不僅影響血液透析的進行甚至會危害病患生命。若能研發簡易的血管血流計，將可協助病患及醫護人員能更有效的監控血管栓塞的形成。此研究為了瞭解雷射穿入皮膚下的深度，藉由蒙地卡羅模擬來模擬光子的行進路徑，並改變入射光光源的角度及感測器接收訊號的距離，以便探討近紅外光穿透皮膚深度及傳遞的距離。從模擬的結果中得知，經由入射角50度與感測器距離為5mm時，所接收到的光穿透最深深度為4.1mm。在流速的量測中，使用自製的雷射都卜勒流速計來量測白色塑膠管內流動的Intrafat，且如模擬的方式改變近紅外光雷射的入射角與感測器的位置，塑膠管並以不同深度埋入Intrafat及gelatin所製備的模擬皮膚組織內，以模擬皮膚底下的廔管。量測的結果中，以30度的入射角只能量測到淺層深度的流速變化，40度則可量測到較為深層的流速變化訊號，而於50度下，不同感測器距離卻對量測深度無明顯的影響。在實際測量管內豬血的流速實驗中， 雷射在40度的入射角下所量測的流速斜率與其餘兩角度有較大的差異性。
並列摘要
Stenosis in arteriovenous fistula is very common in hemodialysis patients. Sometimes it could be life threatening. To develop a simple blood flow velocimeter will be helpful in detecting stenosis at the early stage. A Monte Carlo model was used in this study to simulate the propagation of light in turbid media. The paths of light detected at different distances and with different incident angles were simulated to estimate the measurement region. The results show light injected at a 50 degree angle and detect at a 5 mm distantce can probe the deepest of 4.1 mm. A self made laser Doppler flowmeter was used to measure the flow velocity of Intrafat in a straw tube. The injecting angle and detecting distance are varied as in the simulation. The straw tube was also embedded at different depth in an Intrafat and gelatin mixture to simulate blood vessel in tissue. The flow signal at superficial depth can be detected at 30 degree of incident angle, whereas the flow signal at more depth can be detected at 40 degree of incident angle than 30 degree. When swine’s whole blood was used in the flow measurement, the signal at 40 degree of incident angle can retrieve the deepest flow signal in tissue phantom. The monitoring depth is more confined when the injecting angle is 30 or 50 degree.