應用非對稱感測器陣列於雙平板式正子攝影之影像重建

Abstract

正子攝影是一種廣泛應用於臨床診斷的核子醫學影像系統。近年來有開發出小動物正子攝影影像系統用以針對藥物研究之動物實驗。此類系統雖然具有高解析度，可是由於待測小動物的體積相對人體較小，所以接收到的訊號大小相較之下也較低，為此開發出雙平板式正子斷層掃描系統。此類系統採用兩片大尺寸的感測平板，此種平板式感測器矩陣具有感測區域大，元件密度高的優點，所以在保有高解析度的同時，也能具有高靈敏度的特性。 在此篇論文中，我們提出了一種新型的應用非對稱探測器陣列的雙平板式系統。在這個系統中，兩個平行的感測器使用不同大小的陣列。較小的感測器具有較高解析度的晶體，而較大的感測器則是使用較低解析度的晶體。通過這樣的系統，待測物的細部與整體結構都可以被偵測到。利用這個系統，可以得知細部的資訊，而且不需要兩邊探測平板都使用較高解析度的感測器，因而可以降低成本。這樣的系統可以適用許多臨床方面的應用，例如前列腺癌的偵測。 為了探索系統架構對於實際偵測的潛力，我們採用一種理論方法，此種方法能快速計算評估系統對於偵測病變的能力。得到的理論結果可以幫助我們優化提出的系統配置。

Positron emission tomography is a nuclear medicine imaging systems that is widely used in clinical diagnosis. In recent years, small animal PET system has been developed for drug development of animal experiments. Although such a system has a high-resolution characteristic, the signal to be detected is also lower due to the smaller animal size compared to the human body. To obtain a high sensitivity, a suitable PET system that adopts dual-head flat panel detectors has been proposed. Such a system has the advantages of high component density and a large detection area. Therefore, this kind of system possesses characteristics of both high resolution and high sensitivity. In this work, we developed a novel dual-head flat panel positron emission tomography (PET) system with asymmetric detector arrays. In this system, two detector arrays of different sizes are aligned in parallel. The smaller and larger detector arrays are comprised of crystals of finer and larger sizes, respectively. When an object is imaged by such a system, the detailed features and the general structure of the object can be captured. The design of this system can provide images with detailed description in some certain regions of interest without having to utilize two expensive high-resolution detectors, thereby lowering the cost. Such a system can be applied in many clinical uses such as the screening of prostate cancer. To explore the full potential of system configuration for lesion detection, we employ a theoretical approach that allows fast computation of evaluating the detectability of a lesion. The theoretical results can help us to find the optimization of our proposed system configuration.