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photoacoustic-microscopy
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Image Resolution Improvement in a Photoacoustic Imaging System based on Beamforming
, Ph.D. Dissertation Sharif University of Technology ; Kavehvash, Zahra (Supervisor)
Abstract
The fast-growing development of engineering and medical sciences leads to the diagnosis and treatment of diseases with higher accuracy and in the early stages of the disease. Medical imaging systems are considered as a crucial and effective tool in this field that based on the principle of technology used, are able to image various tissues with high quality. In recent years, photoacoustic imaging has attracted the attention of many researchers and engineers, because it able to image different tissues with good resolution and penetration depth non-invasively and without the use of ionizing radiation. The photoacoustic system response is a low-pass filter that passes only low-frequency...
Fast wavelet-based photoacoustic microscopy
, Article Journal of the Optical Society of America A: Optics and Image Science, and Vision ; Volume 38, Issue 11 , 2021 , Pages 1673-1680 ; 10847529 (ISSN) ; Mostafavi, S. M ; Kavehvash, Z ; Sharif University of Technology
The Optical Society
2021
Abstract
A novel photoacoustic microscopy (PAM) structure, based on Haar wavelet patterns, is proposed in this paper. Its main goal is to mitigate the PAM imaging resolution and thus the time of its sampling process without compromising the image quality. Owing to the intrinsic nature of wavelet transform, this structure collects spatial and spectral components simultaneously, and this feature speeds up the sampling process by 33%. The selection of these patterns helps in better control of required conditions, such as multi-resolution imaging, to guarantee adequate image quality in comparison to previous microscopic structures. Simulation results prove the superior quality of the proposed approach...
Fast wavelet-based photoacoustic microscopy
, Article Journal of the Optical Society of America A: Optics and Image Science, and Vision ; Volume 38, Issue 11 , 2021 , Pages 1673-1680 ; 10847529 (ISSN) ; Mostafavi, S. M ; Kavehvash, Z ; Sharif University of Technology
The Optical Society
2021
Abstract
A novel photoacoustic microscopy (PAM) structure, based on Haar wavelet patterns, is proposed in this paper. Its main goal is to mitigate the PAM imaging resolution and thus the time of its sampling process without compromising the image quality. Owing to the intrinsic nature of wavelet transform, this structure collects spatial and spectral components simultaneously, and this feature speeds up the sampling process by 33%. The selection of these patterns helps in better control of required conditions, such as multi-resolution imaging, to guarantee adequate image quality in comparison to previous microscopic structures. Simulation results prove the superior quality of the proposed approach...
Fourier photoacoustic microscope improved resolution on single-pixel imaging
, Article Applied Optics ; Volume 61, Issue 5 , 2022 , Pages 1219-1228 ; 1559128X (ISSN) ; Amjadian, M ; Kavehvash, Z ; Shabany, M ; Sharif University of Technology
The Optical Society
2022
Abstract
A new single-pixel Fourier photoacoustic microscopy (PAM), to the best of our knowledge, is proposed to improve the resolution and region of interest (ROI) of an acquired image. In the previous structure of single-pixel Fourier PAM, called spatially invariant resolution PAM (SIR-PAM), the lateral resolution and ROI are limited by the digital micromirror device (DMD) pixel size and the number of pixels. This limitation is overcome here through illuminating fixed angle interfering plane waves, changing the fringe frequency via varying the frequency of the laser source. Given that the fringe sinusoidal patterns here can be produced by two mirrors, the DMD usage can be omitted. In this way, the...
Improved Depth-Of-Field and Resolution in Volumetric Photoacoustic Medical Imaging System
, Ph.D. Dissertation Sharif University of Technology ; Kavehvash, Zahra (Supervisor) ; Shabani, Mehdi (Supervisor)
Abstract
Acoustic-resolution photoacoustic microscopy (AR-PAM) system can provide 3-D images of facial tissues. The lateral resolution of AR-PAM depends on the numerical aperture (NA) of the acoustic lens and the central frequency of the ultrasonic transducer. There is a trade-off between resolution enhancement and imaging depth. The acoustic beam is tight in the acoustic focal plane but expands in the out-of-focus regions, deteriorating the resolution. High-NA AR-PAM has depth-variant resolution. Synthetic aperture focusing technique (SAFT) based on a virtual detector (VD) concept can compensate for the beam shape and improve the lateral resolution via beamforming. Although, beamforming can enhance...
Super-resolution photoacoustic microscopy using structured-illumination
, Article IEEE Transactions on Medical Imaging ; Volume 40, Issue 9 , 2021 , Pages 2197-2207 ; 02780062 (ISSN) ; Mostafavi, M ; Chen, J ; Kavehvash, Z ; Zhu, J ; Wang, L ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
A novel super-resolution volumetric photoacoustic microscopy, based on the theory of structured-illumination, is proposed in this paper. The structured-illumination will be introduced in order to surpass the diffraction limit in a photoacoustic microscopy (PAM) structure. Through optical excitation of the targeted object with a sinusoidal spatial fringe pattern, the object's frequency spectrum is forced to shift in the spatial frequency domain. The shifting in the desired direction leads to the passage of the high-frequency contents of the object through the passband of the acoustic diffraction frequency response. Finally, combining the low-frequency image with the high-frequency parts in...