Motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor.
Motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor.
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DOI：
10.1117/1.jbo.29.1.016006
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发表时间：
2024-01
影响因子：
3.5
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中科院分区：
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我们提出了一种具有环境光抑制功能的抗运动三波长空间频域成像 (SFDI) 系统，该系统使用静冈大学开发的 8 抽头互补金属氧化物半导体 (CMOS) 图像传感器 (CIS)。该系统解决了传统 SFDI 系统的局限性，能够在更接近真实条件的挑战性成像场景中进行可靠的测量。我们的研究展示了基于 8 抽头 CIS 的三波长 SFDI 系统。我们通过组织幻影反射实验和体内前臂掌侧实验来演示和评估系统减轻运动伪影和环境光偏差的能力。我们采用希尔伯特变换，将每个波长所需的投影图案数量从每个空间频率的三个减少到两个。 8 抽头图像传感器每个像素有 8 个电荷存储二极管；因此，基于多重曝光同时采集八幅图像是可能的。利用这一功能，传感器可同时采集平面照明、三个波长的正弦图案投影和环境光的图像。通过从其他图像中减去环境光图像来消除环境光偏差。通过减少每个图案的曝光和投影时间，同时通过重复曝光保持足够的信号水平，可以抑制运动伪影。在组织模型实验中将该系统与传统的 SFDI 系统进行比较，然后对人体前臂掌侧进行体内测量。基于 8 抽头图像传感器的 SFDI 系统实现了每秒 9.4 帧组的采集速率，在每个累积周期内重复曝光 3 次。使用传统 SFDI 系统和基于 8 抽头图像传感器的 SFDI 系统的三种不同组织模型的漫反射图显示出良好的一致性，除了高散射模型之外。对于体内掌侧前臂测量，我们的系统成功测量了受试者在运动（16.5 cm/s）和环境光（28.9 lx）下的总血红蛋白浓度、组织氧饱和度和减少的散射系数图，与传统的 SFDI 相比，表现出更少的运动伪影。我们展示了使用 8 抽头 CIS 抑制环境光的抗运动三波长 SFDI 系统的潜力。
We present a motion-resistant three-wavelength spatial frequency domain imaging (SFDI) system with ambient light suppression using an 8-tap complementary metal-oxide semiconductor (CMOS) image sensor (CIS) developed at Shizuoka University. The system addresses limitations in conventional SFDI systems, enabling reliable measurements in challenging imaging scenarios that are closer to real-world conditions. Our study demonstrates a three-wavelength SFDI system based on an 8-tap CIS. We demonstrate and evaluate the system’s capability of mitigating motion artifacts and ambient light bias through tissue phantom reflectance experiments and in vivo volar forearm experiments. We incorporated the Hilbert transform to reduce the required number of projected patterns per wavelength from three to two per spatial frequency. The 8-tap image sensor has eight charge storage diodes per pixel; therefore, simultaneous image acquisition of eight images based on multi-exposure is possible. Taking advantage of this feature, the sensor simultaneously acquires images for planar illumination, sinusoidal pattern projection at three wavelengths, and ambient light. The ambient light bias is eliminated by subtracting the ambient light image from the others. Motion artifacts are suppressed by reducing the exposure and projection time for each pattern while maintaining sufficient signal levels by repeating the exposure. The system is compared to a conventional SFDI system in tissue phantom experiments and then in vivo measurements of human volar forearms. The 8-tap image sensor-based SFDI system achieved an acquisition rate of 9.4 frame sets per second, with three repeated exposures during each accumulation period. The diffuse reflectance maps of three different tissue phantoms using the conventional SFDI system and the 8-tap image sensor-based SFDI system showed good agreement except for high scattering phantoms. For the in vivo volar forearm measurements, our system successfully measured total hemoglobin concentration, tissue oxygen saturation, and reduced scattering coefficient maps of the subject during motion (16.5 cm/s) and under ambient light (28.9 lx), exhibiting fewer motion artifacts compared with the conventional SFDI. We demonstrated the potential for motion-resistant three-wavelength SFDI system with ambient light suppression using an 8-tap CIS.