生物醫學光電造影技術研究

Abstract

對於臨床診斷而言，生物醫學影像系統的進展是一個非常重要的課題，而且生物組織的光學特性至今仍有許多不為人知需要進一步探討的領域。在本研究論文中，我們利用時間、孔徑以及角度遮罩(gating)等方式對假體、雞胸肉以及雞肝組織的穿透訊號加以分析比較，進而發現這三種方法所收集的光子有所不同，但是對於影像品質的提升都有所幫助。因此不同的組織結構應該都有其適合的遮罩方式來提升其影像的品質。所以對不同的生物組織結構尋找適合的遮罩方式是相當值得研究的議題。學同調斷層掃描(Optical coherence tomography, OCT)目前已廣泛應用在許多疾病的診斷上。但在許多狀況下，組織病理上的變化非常的細微，例如像是光學散射特性的變化非常細微以致於非常難以量測得到。因此對於臨床應用上，提升影像對比變得更為重要。其中偏振敏感式光學同調斷層掃描(Polarization-sensitive optical coherence tomography, PSOCT)也就是結合光學同調斷層掃描的解析度並藉由控制光的偏振得以對於具有雙折射特性的生物組織作量測，這是一般光學同調斷層掃描做不到的。這幾十年來，高膽固醇一直都是已開發國家威脅人們健康的主要原因之一，其中有報導指出過多的膽固醇累積在肝臟將會造成其發炎或是纖維化。所以在此論文中，我們利用偏振敏感式光學同調斷層掃描對於具有高膽固醇老鼠的肝臟做離體(in vitro)的量測，進而得到相位延遲(phase retardation)，再進一步推算出雙折射(birefringence)的數值，證實高膽固醇老鼠的肝確實具有雙折射的特性有別於正常老鼠。

Development of biomedical imaging systems is an important issue for diagnosis applications. However, optical properties of biological tissues have not been well understood yet. We have measured transmitted signals with time-, aperture-, and angle-gating for comparison in micro-sphere suspension, chicken breast and chicken liver tissues. Although all the three gating methods might lead to effective biological imaging, they basically collected different portions of transmitted signals for imaging. For biological tissues of different structures, different gating methods might lead to different levels of imaging quality. It is worth exploring a most suitable gating method for a particular kind of tissue. ptical coherence tomography (OCT) has been applied to the scans of various portions of biological tissue, and used for the diagnosis of various diseases. In many situations, such as the pathological process in tissue, changes in the sample scattering property are so small that measurement is difficult. Therefore, for clinical applications, imaging contrast enhancement is an important issue. Polarization-sensitive optical coherence tomography (PSOCT) combines the depth resolution of OCT with polarization-dependent scanning to image the optical birefringence of biological tissues. In the past few decades, hypercholesterolemia has emerged to be a major health threat in the developed world. It has been reported that accumulation of excess cholesterol in the liver results in inflammation and fibrosis. We measure in vitro tissue birefringence in the liver of hypercholesterolemic rats with PSOCT. Tissue birefringence is evaluated through the measurement of phase retardation.