Internal-Illumination Photoacoustic Tomography Enhanced by a Graded-Scattering Fiber Diffuser

The penetration depth of photoacoustic imaging in biological tissues has been fundamentally limited by the strong optical attenuation when light is delivered externally through tissue surface. To address this issue, we previously reported internal-illumination using a customized radial-emission fiber diffuser, which, however, complex fabrication, high cost, and non-uniform emission. overcome these shortcomings, have developed new type low-cost diffusers based on graded-scattering method which scattering diffuser gradually increased as travels. graded can compensate for provide relatively uniform emission along diffuser. We performed Monte Carlo numerical simulations to optimize several key design parameters, including number segments, anisotropy factor, divergence angle fiber, reflective index surrounding medium. These optimized parameters collectively result be flexibly adjusted accommodate different applications. fabricated characterized prototype made agarose gel intralipid. Equipped with thorough proof-of-concept studies ex vivo phantoms an swine model demonstrate deep-imaging capability (~10 cm achieved vivo) tomography. believe that internal delivery via effective strategy image deep targets (e.g., kidney) large animals or humans.