TY - JOUR
T1 - Two-Dimensional Photoacoustic/Ultrasonic Endoscopic Imaging Based on a Line-Focused Transducer
AU - Pang, Weiran
AU - Wang, Yongjun
AU - Guo, Lili
AU - Wang, Bo
AU - Lai, Puxiang
AU - Xiao, Jiaying
N1 - Funding Information:
This research was funded by the Fundamental Research Funds for the Central Universities of Central South University under grant 2018zzts826, the Emergency Science and Technology Project of Hunan Province under grant 2020YJ004, the Department of Science and Technology of Hunan Province, High-tech Industry Science and Technology Innovation Leading Program 2020SK 2003, the Innovation Driven Program team project of Central South University 2020CX004, the National Natural Science Foundation of China under grant 81930048, Guangdong Science and Technology Commission under grants 2019BT02X105, 2019A1515011374, Hong Kong Innovation and Technology Commission under grants GHP/043/19SZ, GHP/ 044/19GD, and Hong Kong Research Grant Council under grants 15217721, R5029-19.
Publisher Copyright:
Copyright © 2022 Pang, Wang, Guo, Wang, Lai and Xiao.
PY - 2022/1/6
Y1 - 2022/1/6
N2 - Existing acoustic-resolution photoacoustic/ultrasonic endoscopy (PA/USE) generally employs a point-focused transducer for ultrasound detection, which is only sensitive in its focal region, thus the lateral resolution and sensitivity drop dramatically when the targets move far from its focus. Even if a dynamic focusing algorithm is applied, the sensitivity out of the transducer focus is still much lower than that in the focus in ultrasonic imaging mode. In this work, we propose an acoustic-resolution PA/USE with a line-focused transducer to realize automatic focusing for the first time. In comparison to a point-focused transducer, the line-focused transducer emits a more uniform sound field, causing the original signal intensity and signal-to-noise ratio (SNR) of the front and rear targets to be closer in the radial direction, which is beneficial for improving target signal uniformity in ultrasonic imaging. Simultaneously, we improved the resolution of the defocus area by modifying a prior work of back-projection (BP) reconstruction algorithm typically used in point-focused transducer based PAE and applying it to line-focused PA/USE. This combined approach may significantly enhance the depth of field of ultrasonic imaging and the resolution of the defocus zone in PA/US imaging, compared to the conventional method. Sufficient numerical simulations and phantom experiments were performed to verify this method. The results show that our method can effectively improve the lateral resolution in the image’s defocused region to achieve automatic focusing and perfectly solve the defect of the target signal difference in the far-focus region in ultrasonic imaging, while also enhancing the image SNR and contrast. The proposed method in this paper lays foundations for the realization of photoacoustic/ultrasonic combined endoscopy with enhanced lateral resolution and depth of field, which can potentially benefit a many of biomedical applications.
AB - Existing acoustic-resolution photoacoustic/ultrasonic endoscopy (PA/USE) generally employs a point-focused transducer for ultrasound detection, which is only sensitive in its focal region, thus the lateral resolution and sensitivity drop dramatically when the targets move far from its focus. Even if a dynamic focusing algorithm is applied, the sensitivity out of the transducer focus is still much lower than that in the focus in ultrasonic imaging mode. In this work, we propose an acoustic-resolution PA/USE with a line-focused transducer to realize automatic focusing for the first time. In comparison to a point-focused transducer, the line-focused transducer emits a more uniform sound field, causing the original signal intensity and signal-to-noise ratio (SNR) of the front and rear targets to be closer in the radial direction, which is beneficial for improving target signal uniformity in ultrasonic imaging. Simultaneously, we improved the resolution of the defocus area by modifying a prior work of back-projection (BP) reconstruction algorithm typically used in point-focused transducer based PAE and applying it to line-focused PA/USE. This combined approach may significantly enhance the depth of field of ultrasonic imaging and the resolution of the defocus zone in PA/US imaging, compared to the conventional method. Sufficient numerical simulations and phantom experiments were performed to verify this method. The results show that our method can effectively improve the lateral resolution in the image’s defocused region to achieve automatic focusing and perfectly solve the defect of the target signal difference in the far-focus region in ultrasonic imaging, while also enhancing the image SNR and contrast. The proposed method in this paper lays foundations for the realization of photoacoustic/ultrasonic combined endoscopy with enhanced lateral resolution and depth of field, which can potentially benefit a many of biomedical applications.
KW - acoustic resolution photoacoustic/ultrasonic endoscopy (PA/USE)
KW - imaging depth of field
KW - improved back-projection imaging algorithm
KW - line-focused transducer
KW - photoacoustic imaging (PAI)
KW - ultrasonic imaging (USI)
UR - http://www.scopus.com/inward/record.url?scp=85123212409&partnerID=8YFLogxK
U2 - 10.3389/fbioe.2021.807633
DO - 10.3389/fbioe.2021.807633
M3 - Journal article
AN - SCOPUS:85123212409
SN - 2296-4185
VL - 9
JO - Frontiers in Bioengineering and Biotechnology
JF - Frontiers in Bioengineering and Biotechnology
M1 - 807633
ER -