Significance: Spatial frequency domain imaging (SFDI) is a quantitative imaging method to measure absorption and scattering of tissue, from which several chromophore concentrations (e.g., oxy-/deoxy-/meth-hemoglobin, melanin, and carotenoids) can be calculated. Employing a method to extract additional spectral bands from RGB components (that we named cross-channels), we designed a handheld SFDI device to account for these pigments, using low-cost, consumer-grade components for its implementation and characterization. Aim: With only three broad spectral bands (red, green, blue, or RGB), consumer-grade devices are often too limited. We present a methodology to increase the number of spectral bands in SFDI devices that use RGB components without hardware modification. Approach: We developed a compact low-cost RGB spectral imager using a color CMOS camera and LED-based mini projector. The components’ spectral properties were characterized and additional cross-channel bands were calculated. An alternative characterization procedure was also developed that makes use of low-cost equipment, and its results were compared. The device performance was evaluated by measurements on tissue-simulating optical phantoms and in-vivo tissue. The measurements were compared with another quantitative spectroscopy method: spatial frequency domain spectroscopy (SFDS). Results: Out of six possible cross-channel bands, two were evaluated to be suitable for our application and were fully characterized (520 ± 20 nm; 556 ± 18 nm). The other four cross-channels presented a too low signal-to-noise ratio for this implementation. In estimating the optical properties of optical phantoms, the SFDI data have a strong linear correlation with the SFDS data (R2 = 0.987, RMSE = 0.006 for μa, R2 = 0.994, RMSE = 0.078 for μs′). Conclusions: We extracted two additional spectral bands from a commercial RGB system at no cost. There was good agreement between our device and the research-grade SFDS system. The alternative characterization procedure we have presented allowed us to measure the spectral features of the system with an accuracy comparable to standard laboratory equipment.

中文翻译：

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用于在资源匮乏环境中进行定量皮肤评估的手持式多光谱成像仪。

意义：空间频域成像 (SFDI) 是一种用于测量组织吸收和散射的定量成像方法，从中可以计算出几种发色团浓度（例如，氧-/脱氧-/甲基-血红蛋白、黑色素和类胡萝卜素）。我们采用一种方法从 RGB 分量（我们称之为跨通道）中提取额外的光谱带，设计了一个手持 SFDI 设备来解释这些颜料，使用低成本的消费级组件来实现和表征。目标：只有三个宽光谱带（红色、绿色、蓝色或 RGB），消费级设备通常过于有限。我们提出了一种方法来增加使用 RGB 组件而无需硬件修改的 SFDI 设备中的光谱带数量。方法：我们使用彩色 CMOS 相机和基于 LED 的微型投影仪开发了一种紧凑型低成本 RGB 光谱成像仪。表征了组件的光谱特性并计算了额外的跨通道频带。还开发了一种使用低成本设备的替代表征程序，并比较了其结果。通过对组织模拟光学体模和体内组织的测量来评估设备性能。将测量结果与另一种定量光谱方法进行比较：空间频域光谱 (SFDS)。结果：在六个可能的跨通道波段中，有两个被评估为适合我们的应用，并被充分表征（520 ± 20 nm；556 ± 18 nm）。对于此实现，其他四个交叉通道的信噪比太低。在估计光学体模的光学特性时，SFDI 数据与 SFDS 数据具有很强的线性相关性（对于 μa，R2 = 0.987，RMSE = 0.006，对于 μs'，R2 = 0.994，RMSE = 0.078）。结论：我们免费从商用 RGB 系统中提取了两个额外的光谱带。我们的设备与研究级 SFDS 系统之间有很好的一致性。我们提出的替代表征程序使我们能够以与标准实验室设备相当的精度测量系统的光谱特征。我们的设备与研究级 SFDS 系统之间有很好的一致性。我们提出的替代表征程序使我们能够以与标准实验室设备相当的精度测量系统的光谱特征。我们的设备与研究级 SFDS 系统之间有很好的一致性。我们提出的替代表征程序使我们能够以与标准实验室设备相当的精度测量系统的光谱特征。