Monte Carlo-Based Optimization of Multi-Source Illumination for Photoacoustic Signal Generation in Human Gray-Matter Vessels.

Effective excitation of cerebrovascular photoacoustic signals is limited by superficial tissue attenuation and illumination geometry. This paper proposes a multi-source illumination evaluation method for gray-matter vessel targets based on Monte Carlo light transport and photoacoustic initial-pressure calculation using a simplified multilayer brain model for screening and a Tissue Probability Map (TPM) brain model for validation. The dual Collimated Gaussian source with 15° symmetric incidence along the Y direction performed best in the regular layered model, whereas the dual Pencil Array source with 20° symmetric incidence along the Y direction was optimal in the TPM model. These results suggest that regular layered models are suitable for preliminary screening, but the final illumination scheme should be revalidated under anatomical constraints. This study provides a theoretical reference for optimizing optical-source configurations in human brain photoacoustic imaging.