以現場可程式化邏輯閘陣列實作光學同調斷層掃描術之成像引擎

Abstract

可攜式之光學同調斷層掃描術(Portable optical coherence tomography, portable OCT)系統為了克服傳統型OCT體積與價格上的限制，在架構上以頻域式光學同調斷層掃描術(Spectral-domain OCT, SD-OCT)為基礎，並透過單板電腦或小型電腦等微型化之低成本運算單元，進行後端OCT影像處理以及周邊掃描設備的控制。然而，使用相對微型化且低成本之運算單元使其受限於效能上的限制，難以提供快速且即時的高品質OCT掃描影像。 本研究為了建立兼顧效能、體積與成本的可攜式OCT系統雛形，開發了一套OCT異質運算架構整合平台，包含了進階精簡指令集機器(Advanced RISC Machine, ARM)架構處理器系統、現場可程式化邏輯閘陣列(Field Programmable Gate Array, FPGA)以及個人電腦。以ARM架構處理器系統作為SD-OCT中的線型相機(Line-scan camera)之控制單元，並利用FPGA進行周邊設備的同步控制以及OCT影像處理，最後透過個人電腦實現即時OCT影像顯示與使用者控制介面。而在OCT架構方面，我們將芯聖科技(OPXION Technology, Inc.)開發的手持式光學同調斷層掃描儀與本研究開發的運算平台結合，以實現完整的可攜式OCT系統。為了實現FPGA與個人電腦的高速資料傳輸，本研究透過通用序列匯流排(Universal serial bus, USB)控制器硬體作為FPGA與個人電腦的連接管道，負責USB封包的傳輸。而ARM架構處理器系統與FPGA的部分則使用Xilinx公司設計的Zynq系列開發版。此開發板本身就搭載了ARM處理器系統與FPGA資源，可透過高速匯流排進行ARM架構處理器系統與FPGA之間的資料傳輸。 在本研究中我們首先使用FPGA開發與USB控制器溝通之介面控制模組，並在電腦端利用USB控制器提供的軟體介面進行資料收發控制，實現了FPGA與電腦端的資料傳輸。接下來我們建立了ARM架構處理器系統與FPGA之間基於高速匯流排的資料溝通機制，並結合先前開發的FPGA與電腦的資料傳輸方法，完成整體系統的傳輸架構，並對其資料傳輸的正確性進行測試。最後，我們開發了SD-OCT影像處理之FPGA硬體模組，結合先前已開發的FPGA同步掃描訊號產生模組並整合於整體系統的傳輸架構中，而經過FPGA處理完的OCT影像將傳輸至個人電腦進行即時影像顯示。本研究利用此異質運算架構整合平台實現以FPGA為基礎之可攜式OCT系統，提供即時的OCT掃描影像，以利可攜式OCT系統應用在更多基礎醫療(Primary care)的場域中。

To overcome the footprint and cost limitation of traditional optical coherence tomography (OCT) systems, most portable optical coherence tomography (portable OCT) systems are based on spectral-domain optical coherence tomography (SD-OCT) and miniaturized computing units such as single-board computers or small PCs for backend OCT image processing and control of peripheral scanning devices. However, utilizing relatively miniaturized and low-cost computing units makes it challenging to provide high-speed, real-time, and high-quality OCT images. This study aims to establish a prototype of a portable OCT system that balances performance, size, and cost by developing an integrated platform for heterogeneous computing architectures. This platform includes an Advanced RISC Machine (ARM) processor system, a Field Programmable Gate Array (FPGA), and a personal computer. The ARM processor system serves as the control unit for the SD-OCT line-scan camera, while the FPGA is utilized for the synchronous control of peripheral devices and OCT image processing. Real-time OCT image display and user control interface are realized through a personal computer. To achieve a complete portable OCT system, we also integrated our computing platform into a handheld OCT scanner developed by OPXION Technology, Inc. To realize the data transmission between the FPGA and the personal computer, a Universal serial bus (USB) controller hardware for USB packet transmission is utilized. A Xilinx Zynq development board equipped with an ARM processor system and FPGA resources is utilized in this platform, featuring the high-speed data transmission bus between the ARM processor system and FPGA. In this study, we first developed the communication interface control module between the FPGA and the USB controller and utilized the software interface provided by the USB controller on the computer side to control data transmission, achieving data transfer between the FPGA and the computer. Next, we established a high-speed bus-based data communication method between the ARM processor system and the FPGA, integrating it into the previously developed FPGA-to-computer data transfer method to complete the overall system transmission architecture and test the correctness of data transmission. Finally, we developed hardware modules for SD-OCT image processing and integrated them into the overall system transmission architecture and the previously developed synchronous scanning waveform generation module with FPGA. The OCT images processed by the FPGA are transmitted to the personal computer for real-time image display. This study realizes an FPGA-based portable OCT system using the heterogeneous computing architecture integration platform, providing real-time OCT scan images to facilitate the application of portable OCT systems in primary care.