In photoacoustic computed tomography (PACT), the "finite aperture effect" is often characterized as a tangential resolution that increases proportionally with the distance from the rotation center. However, this conclusion is based on the inaccurate point-detector assumption used in image reconstruction. In this study, we appropriately modeled the finite size of the acoustic detector in the back-projection (BP) based image reconstruction to improve the accuracy of the time delay calculation and systematically investigated its effects. Our results showed that the main effect of the finite aperture size is the creation of a limited high-quality imaging region (HQIR) around the scanning center, due to the directional sensitivity of the detector. We also demonstrated that the "finite aperture effect" can reduce the optimal number of detectors required for spatial anti-aliasing. These new findings provide novel perspectives for optimizing PACT systems and corresponding reconstruction methods.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.ultras.2023.107042 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Controlling Raman enhancement in particle-aperture hybrid nanostructures by interlayer spacing.
Nanoscale
December 2024
Center for Photonics Sciences, University of Eastern Finland, P.O. Box 111, FI-80101, Joensuu, Finland.
Here we show how surface-enhanced Raman spectroscopy (SERS) features can be fine-tuned in optically active substrates made of layered materials. To demonstrate this, we used DNA-assisted lithography (DALI) to create substrates with silver bowtie nanoparticle-aperture pairs and then coated the samples with rhodamine 6G (R6G) molecules. By varying the spacing between the aperture and particle layer, we were able to control the strength of the interlayer coupling between the plasmon resonances of the apertures and those of the underlying bowtie particles.
View Article and Find Full Text PDFElectron beam lithography is a standard method for fabricating photonic micro and nanostructures around semiconductor quantum dots (QDs), which are crucial for efficient single and indistinguishable photon sources in quantum information processing. However, this technique is difficult for direct 3D control of the structure shape, complicating the design and enlarging the 2D footprint to suppress in-plane photon leakage while directing photons into the collecting lens aperture. Here, we present an alternative approach to employ xenon plasma-focused ion beam (Xe-PFIB) technology as a reliable method for the 3D shaping of photonic structures containing low-density self-assembled InAs/InP quantum dots emitting in the C-band range of the 3rd telecommunication window.
View Article and Find Full Text PDFIn this paper, we report a three-dimensional synthetic aperture imaging method with pulsed terahertz waves realized by a terahertz time-domain spectrometer. In contrast to synthetic aperture imaging systems operating at microwave or millimeter-wave frequencies where the frequency of the transmitter is scanned in the frequency domain, in our imaging system, all the frequency components are contained in a single terahertz pulse that can be generated and detected by photoconductive antennas. The image algorithm was analyzed theoretically and confirmed numerically using the finite-difference time-domain method.
View Article and Find Full Text PDFDetection of effective prestressing of 1860-grade strands based on the microporous method.
Sci Rep
October 2024
Xi'an Keyuan Municipal Engineering Consulting Co, Xi an, 710000, China.
Article Synopsis
- Existing tensioning cable prestress is crucial for ensuring the safety of bridges, and the study introduces a micro-hole release technique for measuring the effective prestress in prestressed concrete bridges.
- The research involved creating a strand drilling model using Solidworks and Abaqus, analyzing variables like drilling depth, diameter, and deflection angle on strand stress relief.
- Results reveal that as hole diameter and depth increase, stress relief varies; specifically, larger holes lead to decreased alleviation, while increased deflection angles raise the error rate in stress release measurements.
Design and optimization of a novel solenoid with high magnetic uniformity.
Sci Rep
October 2024
College of Integrated Circuits, Anhui Polytechnic University, Wuhu, 241000, China.
Currently, solenoids are extensively utilized in various research fields due to their flexibility of fabrication and high magnetic field strength. However, the internal magnetic field of the solenoid itself exhibits some non-uniformity defects, which limits its application in some domains. This article proposes a novel single winding tightly wound solenoid structure with an improved magnetic field uniformity.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!