August 2014
Spotlight Summary by Vivek J. Srinivasan, Dawid Borycki
High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s
Surgical guidance remains an important, yet underdeveloped, application area of optical imaging techniques. In particular, imaging methods such as Optical Coherence Tomography (OCT) offer the tantalizing prospect of adding a third dimension to a physician’s view for improved surgical planning, execution, and outcome assessment. Over the past decade, OCT acquisition speeds have advanced by approximately four orders of magnitude, from speeds of hundreds of axial scans per second to millions of axial scans per second, leading to the present possibility of rapid acquisition of multiple volumetric data sets in a second. However, few groups have managed to handle, process, and display data at this rate in real time, a necessity for applications such as surgical guidance.
In this study, Wieser et al. describe a live 4D OCT engine achieving a rate of 1 GVoxel/s, a major advance in this direction. The authors combined advanced graphics processing unit (GPU) programming with state-of-the-art rapidly tunable laser sweeping, buffering, and acquisition. In particular, previous studies on 4D OCT processing using GPUs suffered from long data transfer between the host computer and GPU memory. The authors solved this issue by constructing multi-threaded software, which asynchronously transfers data from hardware and processes it simultaneously using a dual GPU card. Using such an approach the authors achieve a sustained voxel rate five times higher than previous studies. Video rate 4D OCT requires an A scan rate in the megahertz range. Towards this end, the authors developed a Fourier domain mode-locked (FDML) laser with a dual fiber Bragg grating dispersion compensation module, and operate on the 5th harmonic of the cavity at 402 kHz. This sweep rate was further enhanced to 3.2 MHz by buffering the output of FDML laser.
In conclusion, the advances in real time imaging presented in this study are exciting, and have implications beyond surgical guidance, including real-time analysis of complex three-dimensional systems including turbulent flow and biomechanics, as well as in volumetric functional imaging.
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In this study, Wieser et al. describe a live 4D OCT engine achieving a rate of 1 GVoxel/s, a major advance in this direction. The authors combined advanced graphics processing unit (GPU) programming with state-of-the-art rapidly tunable laser sweeping, buffering, and acquisition. In particular, previous studies on 4D OCT processing using GPUs suffered from long data transfer between the host computer and GPU memory. The authors solved this issue by constructing multi-threaded software, which asynchronously transfers data from hardware and processes it simultaneously using a dual GPU card. Using such an approach the authors achieve a sustained voxel rate five times higher than previous studies. Video rate 4D OCT requires an A scan rate in the megahertz range. Towards this end, the authors developed a Fourier domain mode-locked (FDML) laser with a dual fiber Bragg grating dispersion compensation module, and operate on the 5th harmonic of the cavity at 402 kHz. This sweep rate was further enhanced to 3.2 MHz by buffering the output of FDML laser.
In conclusion, the advances in real time imaging presented in this study are exciting, and have implications beyond surgical guidance, including real-time analysis of complex three-dimensional systems including turbulent flow and biomechanics, as well as in volumetric functional imaging.
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Article Information
High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s
Wolfgang Wieser, Wolfgang Draxinger, Thomas Klein, Sebastian Karpf, Tom Pfeiffer, and Robert Huber
Biomed. Opt. Express 5(9) 2963-2977 (2014) View: Abstract | HTML | PDF