Local laser fluence estimation model in optical resolution optoacoustic microscopy
Daria Voitovich 1,2, Alexey Kurnikov 1, Anna Orlova 1,2, Liubov Shimolina 2,
Anastasia Komarova 2, Marina Shirmanova 2, Yu-Hang Liu 3,4, Daniel Razansky 3,4 Pavel Subochev 1,2
1 Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod 603950, Russia
2 Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Nizhny Novgorod 603005, Russia
3 Institute for Biomedical Engineering and Institute of Pharmacology and Toxicology, Faculty of Medicine, UZH Zurich, Ramistrasse ¨ 71, Zurich 8006, Switzerland
4 Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, Zurich 8092, Switzerland
Abstract
Optical-resolution optoacoustic microscopy (OR-PAM) is a hybrid imaging technique that combines focused optical excitation with ultrasound detection, enabling micrometer-scale spatial resolution and high-contrast angiographic imaging. Maintaining safe laser fluence levels is critical to avoid tissue damage while ensuring sufficient detection sensitivity. In this work, we present a model that directly relates the detector’s noise-equivalent pressure (NEP) to the local laser fluence at the imaged blood vessel. The model accounts for acoustic propagation effects from an optoacoustic source to a spherically focused detector with finite aperture and bandwidth. The effects of ultrasound generation, propagation, and detection were analyzed using both analytical approximations and numerical simulations, while the detector’s NEP was experimentally determined using a calibrated hydrophone. The proposed model for local fluence estimation with a calibrated ultrasound detector was validated through in vitro experiments with superficial blood layers and numerical Monte Carlo/k-Wave simulations of deeper vessels. In vivo experiments using 532 nm laser excitation and broadband (1–30 MHz) ultrasound detection further demonstrated the model’s ability to adjust laser parameters in real time to ensure tissue safety.
Speaker
Daria Voitovich
Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod 603950, Russia
Россия
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