METHOD AND SYSTEM FOR USING VIRTUAL ACCOUNT

The present disclosure provides a method and a system for using a virtual account. The method comprises receiving first account identifier data associated with a first account of a first party. A first token may be generated based on the first account identifier. Second account identifier data associated with a second account of a second party may be received. A second token may be generated based on the second account identifier. First request data associated with a request to establish a virtual account may be received. A virtual account may be generated and may be funded by the second account associated with the second party. Invoice data associated with a transaction between the first party and the second party may be received. A transaction amount (e.g., from the invoice) may be debited from the virtual account and/or credited to the first account

Time-domain reconstruction algorithms and numerical simulations for thermoacoustic tomography in various geometries

In this paper, we present time-domain reconstruction algorithms for the thermoacoustic imaging of biological tissues. The algorithm for a spherical measurement configuration has recently been reported in another paper. Here, we extend the reconstruction algorithms to planar and cylindrical measurement configurations. First, we generalize the rigorous reconstruction formulas by employing Green's function technique. Then, in order to detect small (compared with the measurement geometry) but deeply buried objects, we can simplify the formulas when two practical conditions exist: 1) that the high-frequency components of the thermoacoustic signals contribute more to the spatial resolution than the low-frequency ones, and 2) that the detecting distances between the thermoacoustic sources and the detecting transducers are much greater than the wavelengths of the high-frequency thermoacoustic signals (i.e., those that are useful for imaging). The simplified formulas are computed with temporal back projections and coherent summations over spherical surfaces using certain spatial weighting factors. We refer to these reconstruction formulas as modified back projections. Numerical results are given to illustrate the validity of these algorithms

Photoacoustic imaging in biomedicine

Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorptioncontrasts, (2) breast cancerdetection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorptioncontrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging

RF-induced thermoacoustic tomography

We present our study of pulsed-microwave-induced thermoacoustic tomography under a circular measurement configuration in biological tissues. A wide beam of short-pulse microwave (radio-frequency, RF) energy is used to illuminate a sample from the bottom. An unfocused ultrasonic transducer with a small aperture is used to record the thermoacoustic signals from the side. A backprojection method based on a rigorous theory is used to reconstruct the cross-sectional image from the measured data. The reconstructed image agrees with the original sample very well

Time-domain reconstruction for thermoacoustic tomography in a spherical geometry

Reconstruction-based microwave-induced thermoacoustic tomography in a spherical configuration is presented. Thermoacoustic waves from biological tissue samples excited by microwave pulses are measured by a wide-band unfocused ultrasonic transducer, which is set on a spherical surface enclosing the sample. Sufficient data are acquired from different directions to reconstruct the microwave absorption distribution. An exact reconstruction solution is derived and approximated to a modified backprojection algorithm. Experiments demonstrate that the reconstructed images agree well with the original samples. The spatial resolution of the system reaches 0.5 mm

Spatial resolution in three-dimensional photo-acoustic reconstruction

We present an analytic explanation of the spatial resolution in three-dimensional photo-acoustic (also called opto-acoustic or thermo-acoustic) reconstruction. Based on rigorous reconstruction formulas, we analytically derive the point-spread functions (PSFs) for three types of specific recording geometries, including spherical, planar, and cylindrical surfaces. The PSFs as a function of the bandwidth of the measurement system and the finite size of the detector aperture, as well as the discrete sampling effect on the reconstruction, are investigated. The analyses clearly reveal that the dependence of the PSFs on the bandwidth of all of the recording geometries shares the same space-invariant expression while the dependence on the aperture size of the detector differs. The bandwidth affects both axial and lateral resolution; in contrast, the detector aperture blurs the lateral resolution greatly but the axial resolution only slightly. Under-sampling in the measurement causes significant aliasing artifacts in the reconstruction. A general sampling strategy to avoid aliasing is proposed