Industry-Standard Platforms Allow Efficient System Integration

Santec used NI FlexRIO to prototype a new architecture and FPGA-based image processing for their low-cost, portable OCT imaging system.
A system that is flexible and scalable to meet future requirements can be highly valuable for a development team, but these features are often some of the first to go when a development schedule slips. One way to tackle this problem is to build modular systems using an industry-standard platform with a wide variety of I/O. This way, a developer can leverage a combination of custom and off-the-shelf hardware early in the design process to quickly show a working prototype. Ideally, this platform should be flexible enough to combine off-the-shelf CPU and FPGA-based processing, scale to add higher channel counts or even other imaging modalities, and include a variety of I/O for high performance and lower speed signal acquisition, generation, and control.

Researchers at Kitasato University in Japan recently showed the power of using a flexible and scalable platform when they demonstrated the world’s first real-time 3D Optical Coherence Tomography (OCT) imaging system. While their specific OCT research area may not apply to other imaging system designers, the more important takeaway is that they chose a platform that could integrate the multiple technologies required for their high-performance design. Specifically, they chose the PXI platform, which provided high throughput data transfers over PCI Express, accurate timing and synchronization of multiple modules, a wide variety of I/O, and the ability to create “peer-to-peer data streams” that connect multiple FPGA modules over direct memory access (DMA) without ever needing to involve the host.

Since the research team’s goal is to move toward real-time optical biopsy, their target was real-time display of 3D OCT images at a rate of 12 volumes per second. Their system contained a total of 22 FPGA modules, which combined data from 320 channels (each acquiring data at 10 MS/s), as well as performing noise subtraction, windowing and FFT processing. To achieve their 3D imaging capabilities, the two highest performance processing FPGAs in the system computed over 700,000 512-point FFTs every second.

Using LabVIEW to integrate and control the different parts of the system, they transferred data from the FPGA subsystem to a quad-core PC with an NVIDIA FX3800 Graphics Processing Unit (GPU) to perform real-time 3D rendering and display. They also needed to log data for extended time periods since they wanted to be able to conduct group screening tests for cancer. While their architecture doesn’t limit the image acquisition time, the research team enabled logging of up to 100 minutes on their prototype system, which required a little more than 3 TB of hard drive space.

Bringing Everything Together

Researchers at Kitasato University in Japan combined FPGA and GPU processing to create the world’s first system capable of real-time, 3D OCT imaging. Snapshots of finger skin (top and side view) from the system are shown.
The need for imaging system designers to deliver innovative new products under tight timelines is unlikely to change, but FPGA technology combined with the right integration platform can help make this process more efficient. Diagnostic imaging modalities continue to advance with new algorithms, higher performance processing, and better hardware. By combining modular, off-the-shelf FPGA hardware with high-level design tools, system developers can create flexible and scalable systems to meet the needs of these next-generation imaging systems.

This article was written by John Hottenroth, Market Development Manager for National Instruments, Austin, TX. For more information, Click Here