GPU accelerated regional lung air volume measurements from phase contrast X-ray images

Abstract

Phase contrast X-ray imaging can provide significantly enhanced visibility of soft tissues over absorption contrast imaging with spatial resolution on the micron scale. These characteristics have enabled the visualisation of lungs aerating at birth in real time. We have developed techniques to measure regional lung air volume from these images to help develop methods for safely ventilating the lungs of preterm infants. However, analyzing a large sequence of image data requires considerable computation time on traditional desktop computers. Real-time feedback of the regional ventilation would greatly benefit researches to optimize ventilation strategies. The present paper describes methods for improving the execution time of the lung volume measurements using graphics processing units (GPUs). We tested the performance of the GPU-accelerated lung volume computations using two different GPUs and compared the results with two CPUs. An overall speedup of 1.75---14.12× was achieved if an absorption contrast-based computation was used for volumetric computation, while a 2.43---15.78× speedup was attained in the case of a more compute bound phase retrieval technique. This speedup enabled us to perform lung air volume reconstruction on a local computer with the analysis taking only a few minutes, which is very helpful to guide our experiments in the laboratory. We also show that the accuracy of the GPU-based lung volume measurements was in excellent agreement with the CPU-based counterpart.