Suppose D is a bounded, connected, open set in Rn and f smooth function on with support $\overD$. We study the recovery of from mean values over spheres centered part or whole boundary D. For strictly convex $\overline{D}$, we prove uniqueness when centers are restricted to an subset boundary. provide inversion algorithm (with proof) known for all D, radii interval [0, diam(D)/2]. also give formula ball Rn, $n \geq 3$ odd,

The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized inaccuracies range verification. purpose this work was correlate location with target structure, by overlaying onto a standard ultrasound image. Pulsed delivery 50 MeV protons accomplished fast chopper installed between ion source and cyclotron inflector. limited train bunches so that 2 Gy were delivered . pulse generated thermoacoustic pulses detected cardiac array, which also...

Thermoacoustics has the potential to provide quantitative images of intrinsic tissue properties, most notably electrical conductivity in Siemens/meter, much as shear wave elastography provides stiffness kilopascal. Although thermoacoustic imaging with optical excitation been commercialized for small animals, it not yet made transition clinic whole organ humans. The purpose this work was develop and validate specifications a clinical ultrasound array imaging. Imaging large requires exciting...

Hybrid imaging techniques using either radiofrequency (RF) or near-infrared radiation (NIR) as excitation energy measure averages of tissue RF/NIR absorptivity over spheres centred at ultrasound (US) transducer locations on the bottom a spherical bowl, where [z < 0]. Inversion formulae for 'complete data' case transducers all bowl weight data from lower hemisphere more heavily reconstructions points also satisfying (z We derive consistency conditions and use them to compute unmeasured...

Enhanced heating of nanoparticles for applications such as thermoacoustic imaging and therapeutic heat delivery is considered. The optimum electrical conductivity to achieve maximum electromagnetic energy deposition in a given nanoparticle obtained, with emphasis on rf frequencies, where plasmon resonances associated negative permittivity are generally not possible. Spheres, coated spheres, nanowires, carbon nanotubes In all cases, it found that relatively small values (e.g., σ⪡1 S/m...

The broadband ultrasonic characterization of biological fluids and tissues is important for the continued development application high-resolution ultrasound imaging modalities. Here, a photoacoustic technique transmission measurement temperature-dependent attenuation dispersion described. system uses plane wave source constructed from polymethylmethacrylate substrate with thin optically absorbent layer. Broadband waves are generated by illuminating layer nanosecond pulses laser light....

Thermoacoustic signals are generated over a large field of view by 900 ns TE10 pulses with 108 MHz carrier frequency. Test specimens selectively absorb the pulse energy producing rapid thermal expansions that generate ultrasonic pulses. irradiation provides excellent depth penetration in soft tissue, allowing blood and physiologic saline to strong signals. signal generation from several cm is well above our systems noise floor. Rotating test specimen single-slice tomographic encoding....

Purpose Range errors constrain treatment planning by limiting choice of ion beam angles and requiring large margins. Ionoacoustic range verification requires recovering the location an acoustic source from low frequency signals. A priori information is applied to stably overcome resolution limits inverse imaging in this simulation study. In particular, accuracy robustness ionoacoustic for lateral oblique delivery high‐energy protons prostate examined. Methods Dose maps were computed using...

Source trajectories and reconstruction algorithms for clinical volumetric computerized tomography (VCT) will require optimization efficiency image quality. VCT data is highly overdetermined, satisfying an ultrahyperbolic partial differential equation. Characteristic boundary value problems the hyperbolic wave equation are compared, focusing in this paper on a mathematically instructive open-gantry geometry. This example provides physical insight into consistency conditions upon data, clearly...

Electromagnetic absorption and subsequent heating of nanoparticle solutions simple NaCl ionic is examined for biomedical applications in the radiofrequency range at 13.56 MHz. It shown via both theory experiment that vitro measurements shape solution container plays a major role heating.

Purpose To demonstrate robustness of thermooacoustic range verification to acoustic heterogeneity and discrepancies between assumed true propagation speed, i.e., soundspeed errors. Methods A beam sweeper was used deliver 250 ns pulses that deposited 0.26 Gy 16 MeV protons 2.3 60 helium ions into water oil targets, respectively. Thermoacoustic signals were detected by a 96‐channel ultrasound array with 1–4 MH z sensitivity band (−6 dB ), bandpass filtered backprojected create thermoacoustic...

Thermoacoustic signal excitation is a function of intrinsic tissue properties and illuminating electric field. De-ionized (DI) water preferred acoustic coupling medium for thermoacoustics because electromagnetic waves propagate in DI with very little loss. We have designed water-filled testbed propagating controlled field respect to pulse shape, power, polarization. Directional coupler line sections permit measurement incident, reflected, transmitted powers. Both S-parameters Ey show that...

Applying the thermoacoustic (TA) effect to diagnostic imaging was first proposed in 1980s. The object under test is irradiated by high-power pulses of electromagnetic energy, which heat tissue and cause thermal expansion. Outgoing TA pressure are detected ultrasound transducers reconstructed provide images object. contrast mechanism strongly dependent upon frequency irradiating pulse.

The ability of extremely and very low frequency (ELF/VLF, 0-30 kHz) radio waves to penetrate conductive media is well established. Magnetic field penetration into a thin but highly box using an ELF/VLF loop antenna transmitter investigated. work relevant for electromagnetic shielding sensors, defect detection, inductive power transfer, through container imaging. Analytical solutions are reviewed related problems, however, determining the realistic shield geometry finite sized near-field...

We compute unmeasured cone-beam projections from measured by a third-generation helical volumetric computed tomography system solving characteristic problem for an ultrahyperbolic differential equation [John (1938)]. By working in the Fourier domain, we convert second-order PDE into family of first-order ordinary equations. A simple integration is used to solve ODES.

The thermoacoustic (TA) contrast mechanism relies on rapid tissue heating and subsequent thermal expansion. TA computerized tomography (TCT) is therefore inverse source imaging. provides information complementary to that revealed by current diagnostic imaging techniques, but has been limited just a few centimeters depth penetration. In this article, whole organ TCT demonstrated large swine kidney. sinograms show signal generated high-power, very high frequency (VHF) electromagnetic pulses...

Filtered backprojection (FBP) reconstruction is the method of choice for diagnostic xray CT, despite fact that computationally costly. FBP image quality superior over fast Fourier techniques because interpolation errors are localized and backprojector applies Radon transform, annihilating all measurement orthogonal to its range. We discuss computational complexity, sampling rates, quadrature thermo/photo/optoacoustic data.

The specific heat capacity of tissue is a critical parameter for thermal therapies that act over long period time. It also thermoacoustic signal generation. We present ex vivo measurements performed by dual-pin probe with tight temperature control the specimen. One 30 mm × 1.28 heats steadily s, while another measurement measures temperatures 6 away from center heater probe. Specific values ranging 2.9 to 4 J cm−3 °C−1 were measured on 20 lobes ten fresh prostate specimens varying degrees...

The problem of image reconstruction in thermoacoustic tomography requires inversion a generalized Radon transform, which integrates the unknown function over circles 2D or spheres 3D. paper investigates implementation recently discovered backprojection type formulas for case spherical acquisition A numerical simulation data with subsequent reconstructions are made Defrise phantom as well some other phantoms. Both full and partial scan situations considered. results compared previously used...

Abstract Objective. Mapping of dose delivery in proton beam therapy can potentially be performed by analyzing thermoacoustic emissions measured ultrasound arrays. Here, a method is derived and demonstrated for spatial mapping sources using numerical time reversal, simulating re-transmission into the medium. Approach. Spatial distributions emission are shown to approximated analytic-signal form time-reversed acoustic field, evaluated at initial pulse. Given calibration array sensitivity...

Recent developments in optical imaging inspired the model of photon transport discussed below. (Infrared radiation is used to image relatively soft and homogeneous tissue.) The difficulty solving Maxwell’s equations, or even linear led this ‘‘diffuse tomographic’’ model. A recursive scheme for two-dimensional problem sketched first step detailed.

Thermoacoustic computerized tomography (TCT) is a hybrid imaging technique exploiting the thermoacoustic effect. TCT has many parallels with X-ray CT, including frequency dependent attenuation of measured signal. However, nature these phenomena nearly opposite: beams "harden", whereas ultrasound pulses "soften" An analytic formula for an attenuated pulse generat.ed by homogeneous spherical inclusion presented. Resulting artifacts in reconstructed CT and images are compared contrasted.