Photoacoustic differential attenuation spectrum for bone assessment

Photoacoustic (PA) technology shows great potential in bone microstructure assessment. Due to the solid-liquid two-phase characteristics of cancellous bone, the PA signal received by transducers is aliasing of distributed PA source characteristics and acoustic propagation characteristics of cancellous bone. The contribution of various multi-scale distributed PA sources to the PA signal complexity leads to difficulty in identifying the sound propagation characteristics, making it difficult for quantitative assessment of bone microstructure. To eliminate the spectrum contribution of the PA source to the PA signal, we proposed an eccentric excitation-differential detection system and the acoustic propagation characteristics of cancellous bone can be obtained by calculating the PA differential attenuation spectrum (PA-DAS). The PA-DAS quantization parameter- slope is further extracted to quantify the attenuation of different frequency components. Simulation results show that slope strongly correlates to the porosity of cancellous bone, demonstrating the eccentric excitation-differential detection system combined with the PA-DAS method can realize the quantitative bone assessment.