J Biomed Opt. 2014 Mar;19(3):37001. doi: 10.1117/1.JBO.19.3.037001.
Currently, laser fluence calibration is typically required for quantitative measurement of particle concentration in photoacoustic imaging. Here, we present a calibration-free method to quantify the absolute particle concentration by statistically analyzing photoacoustic signals. The proposed method is based on the fact that Brownian motion induces particle count fluctuation in the detection volume. If the count of particles in the detection volume is assumed to follow the Poisson distribution, its expected value can be calculated by the photoacoustic signal mean and variance. We first derived a theoretical model for photoacoustic signals. Then, we applied our method to quantitative measurement of different concentrations of various particles, including red blood cells. Finally, we performed in vivo experiments to demonstrate the potential of our method in biological applications. The experimental results agreed well with the predictions from the theoretical model suggesting that our method can be used for noninvasive measurement of absolute particle concentrations in deep tissue without fluence calibration.
目前，激光能量密度校准通常是光声成象定量测量粒子浓度所必需的。在这里，我们提出了一种通过统计分析光声信号来定量测量绝对粒子浓度的无校准方法。该方法基于布朗运动在检测体积中引起粒子计数波动的事实。如果假设检测体积中的粒子数遵循泊松分布，则可以通过光声信号的平均值和方差来计算其期望值。我们首先推导了光声信号的理论模型。然后，我们将我们的方法应用于不同浓度的各种粒子的定量测量，包括红细胞。最后，我们进行了体内实验，证明了我们的方法在生物应用中的潜力。实验结果与理论模型的预测吻合较好，表明我们的方法可以用于无能量密度校准的深层组织中绝对粒子浓度的非侵入性测量。
