Photoacoustic Imaging: Consideration of Bandwidth of Ultrasonic Transducer

摘要

Photoacoustic tomography is a potential and noninvasive medical imaging technology. It combines the advantages of pure optic imaging and pure ultrasound imaging. Photoacoustic signals induced by a short pulse laser cover a wide spectral range. We have explored the frequency spectrum of absorbers with different sizes and the influence of photoacoustic signals with different spectral components on photoacoustic imaging. The simulations and experiments demonstrated that the major frequency ranges of photoacoustic pressures of absorbers with diameters of ～ cm, ～ mm and hundreds of μm are about 20kHz ～ 300kHz, 70kHz ～ 2.5MHz and 400kHz ～ 20MHz, respectively. The low spectral components of photoacoustic signals contribute to the non-boundary region of absorbers, and the high spectral components contribute to small structures, especially, to boundaries. It suggests that the ultrasonic transducers used to detect photoacoustic pressures should be designed and selected according to the frequency ranges of absorbers.