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Port wine birthmark, also known as port wine stain (PWS) is a skin discoloration characterized by red/purple patches caused by vascular malformation. PWS is typically treated by using lasers to destroy abnormal blood vessels. The laser heating facilitates selective photothermolysis of the vessels and attenuates quickly in the tissue due to high optical scattering. Therefore, residual abnormal capillaries deep in the tissue survive and often lead to the resurgence of PWS. Ultrasound (US) has also been proposed to treat PWS, however, it is nonselective with respect to the vasculature but penetrates deeper into the tissue. We aim to study the feasibility of a hybrid PWS treatment modality combining the advantages of both modalities.In this manuscript, we propose a photoacoustic (PA) guided US focusing methodology for PWS treatment which combines the optical contrast-based selectivity with US penetration to focus the US energy onto the vasculature. The PA signals collected by the transducers, when time-reversed, amplified, and transmitted, converge onto the PWS, thus minimally affecting the neighboring tissue. We performed two- and three-dimensional simulations that mimic realistic transducers and medium properties in this proof of concept study.The time-reversed PA signals when transmitted from the transducers converged onto the vasculature, as expected, thus reducing the heating of the neighboring tissue. We observed that while the US focus is indeed affected due to experimental factors such as limited-view, large detector separation and finite detection bandwidth, and so forth, the US did focus completely or partially onto the vasculature demonstrating the feasibility of the proposed methodology.The results demonstrate the potential of the proposed methodology for PWS treatment. This treatment method can destroy the deeper capillaries while minimally heating the neighboring tissue, thus reducing the chances of the resurgence of PWS and as well as cosmetic scarring.

Cancer has been and continues to be a leading cause of death globally. More than half of all cancer patients undergo ionizing radiation therapy and dosimetry is crucial to the success and improvement of these treatments - ensuring that an accurate radiation dose is delivered to the target location. Despite widespread clinical use, the delivered dose can only be planned and verified via simulations with phantoms, and an in-tumor, on-line dose verification is still unavailable after more than one-hundred years of clinical application. X-ray-induced acoustic computed tomography (XACT) has recently shown the potential for imaging the delivered radiation dose within the tumor. Prior XACT imaging systems require tens of averages to achieve reasonable images. Here, we demonstrate that our XACT signals can be detected for each individual X-ray pulse (4µs) with sub-mGy sensitivity from a clinical linear accelerator during radiotherapy. Single-pulse XACT imaging holds great potential for personalized precision radiotherapy.

BackgroundOsteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and the deterioration in bone microarchitecture, which might be related to age and space travel. An unmet need exists for the development of novel imaging technologies to characterize osteoporosis.PurposeThe purpose of our study is to investigate the feasibility of X-ray-induced acoustic computed tomography (XACT) imaging for osteoporosis detection.MethodsAn in-house simulation workflow was developed to assess the ability of XACT for osteoporosis detection. To evaluate this simulation workflow, a three-dimensional digital bone phantom for XACT imaging was created by a series of two-dimensional micro-computed tomography (micro-CT) slices of normal and osteoporotic bones in mice. In XACT imaging, the initial acoustic pressure rise caused by the X-ray induce acoustic (XA) effect is proportional to bone density. First, region growing was deployed for image segmentation of different materials inside the bone. Then k-wave simulations were deployed to model XA wave propagation, attenuation, and detection. Finally, the time-varying pressure signals detected at each transducer location were used to reconstruct the XACT image with a time-reversal reconstruction algorithm.ResultsThrough the simulated XACT images, cortical porosity has been calculated, and XA signal spectra slopes have been analyzed for the detection of osteoporosis. The results have demonstrated that osteoporotic bones have lower bone mineral density and higher spectra slopes. These findings from XACT images were in good agreement with porosity calculation from micro-CT images.ConclusionThis work explores the feasibility of using XACT imaging as a new imaging tool for Osteoporosis detection. Considering that acoustic signals are generated by X-ray absorption, XACT imaging can be combined with traditional X-ray imaging that holds potential for clinical management of osteoporosis and other bone diseases.

Dose delivery uncertainty is a major concern in proton therapy, adversely affecting the treatment precision and outcome. Recently, a promising technique, proton-acoustic (PA) imaging, has been developed to provide real-time

X-ray-induced acoustic computed tomography (XACT) is a promising imaging modality to monitor the position of the radiation beam and the deposited dose during external beam radiotherapy delivery. The purpose of this study was to investigate the feasibility of using a transperineal ultrasound (TPUS) transducer array for XACT imaging to guide the prostate radiotherapy. A customized 2-D matrix ultrasound transducer array with 10000 ( $100\times 100$ elements) ultrasonic sensors with a central frequency of 1 MHz was designed on a 5 cm $\times5$ cm plane to optimize 3-D volumetric imaging. The CT scan and dose treatment plan for a prostate patient undergoing intensity-modulated radiation therapy (IMRT) were obtained. The in-house simulation was developed to model the time varying X-ray induced acoustic (XA) signals detected by the TPUS array. A 3-D filtered back projection (FBP) algorithm has been used for 3-D XACT image reconstruction. The results of this study will greatly enhance the potential of XACT imaging for real-time in vivo dosimetry during radiotherapy.

X-ray-induced acoustic computed tomography (XACT) is a promising imaging modality combining high X-ray absorption contrast with the 3-D propagation advantages provided by high-resolution ultrasound waves. The purpose of this study was to optimize the configuration of a 3-D XACT imaging system for bone imaging. A 280 ultrasonic sensors with peak frequency of 10 MHz was designed to distribute on a spherical surface to optimize the 3-D volumetric imaging capability. We performed both theoretical calculations and simulations of this optimized XACT imaging configuration on a mouse-sized digital phantom containing various X-ray absorption coefficients. Iteration algorithm based on total variation has been used for 3-D XACT image reconstruction. The spatial resolution of imaging was estimated to about $130~\mu \text{m}$ along both axial and lateral directions. We simulate XACT imaging of bone microstructures using digital phantoms generated from micro-CT images of real biological samples, showing that XACT imaging can provide high-resolution imaging of the mouse paw. Results of this study will greatly enhance the potential of XACT imaging in the evaluation of bone diseases for future clinical use.

Purpose The aim of this study is to investigate the feasibility of x-ray-induced acoustic computed tomography (XACT) as an image guidance tool for tracking x-ray beam location and monitoring radiation dose delivered to the patient during stereotactic partial breast irradiation (SPBI). Methods An in-house simulation workflow was developed to assess the ability of XACT to act as an in vivo dosimetry tool for SPBI. To evaluate this simulation workflow, a three-dimensional (3D) digital breast phantom was created by a series of two-dimensional (2D) breast CT slices from a patient. Three different tissue types (skin, adipose tissue, and glandular tissue) were segmented and the postlumpectomy seroma was simulated inside the digital breast phantom. A treatment plan was made with three beam angles to deliver radiation dose to the seroma in breast to simulate SPBI. The three beam angles for 2D simulations were 17°, 90° and 159° (couch angles were 0 degrees) while the angles were 90 degrees (couch angles were 0°, 27°, 90°) in 3D simulation. A multi-step simulation platform capable of modelling XACT was developed. First, the dose distribution was converted to an initial pressure distribution. The propagation of this pressure disturbance in the form of induced acoustic waves was then modeled using the k-wave MATLAB toolbox. The waves were then detected by a hemispherical-shaped ultrasound transducer array (6320 transducer locations distributed on the surface of the breast). Finally, the time-varying pressure signals detected at each transducer location were used to reconstruct an image of the initial pressure distribution using a 3D time-reversal reconstruction algorithm. Finally, the reconstructed XACT images of the radiation beams were overlaid onto the structure breast CT. Results It was found that XACT was able to reconstruct the dose distribution of SPBI in 3D. In the reconstructed 3D volumetric dose distribution, the average doses in the GTV (Gross Target Volume) and PTV (Planning Target Volume) were 86.15% and 80.89%, respectively. When compared to the treatment plan, the XACT reconstructed dose distribution in the GTV and PTV had a RMSE (root mean square error) of 2.408 % and 2.299 % over all pixels. The 3D breast XACT imaging reconstruction with time-reversal reconstruction algorithm can be finished within several minutes. Conclusions This work explores the feasibility of using the novel imaging modality of XACT as an in vivo dosimeter for SPBI radiotherapy. It shows that XACT imaging can provide the x-ray beam location and dose information in deep tissue during the treatment in real time in 3D. This study lays the groundwork for a variety of future studies related to the use of XACT as a dosimeter at different cancer sites.

Objective. Proton therapy as the next generation radiation-based cancer therapy offers dominant advantages over conventional radiation therapy due to the utilization of the Bragg peak; however, range uncertainty in beam delivery substantially mitigates the advantages of proton therapy. This work reports using protoacoustic measurements to determine the location of proton Bragg peak deposition within a water phantom in real time during beam delivery. Approach. In protoacoustics, proton beams have a definitive range, depositing a majority of the dose at the Bragg peak; this dose is then converted to heat. The resulting thermoelastic expansion generates a 3D acoustic wave, which can be detected by acoustic detectors to localize the Bragg peak. Main results. Protoacoustic measurements were performed with a synchrocyclotron proton machine over the exhaustive energy range from 45.5 to 227.15 MeV in clinic. It was found that the amplitude of the acoustic waves is proportional to proton dose deposition, and therefore encodes dosimetric information. With the guidance of protoacoustics, each individual proton beam (7 pC/pulse) can be directly visualized with sub-millimeter (Significance. The ability to localize the Bragg peak in real-time and obtain acoustic signals proportional to dose within tumors could enable precision proton therapy and hope to progress towards in vivo measurements.

X-ray induced acoustic computed tomography (XACT) provides X-ray absorption based contrast with acoustic detection. For its clinical translation, XACT imaging often has a limited field of view. This can result in image artifacts and overall loss of quantification accuracy. In this article, we aim to demonstrate model-based XACT image reconstruction to address these problems. An efficient matrix-free implementation of the regularized LSQR (MF-LSQR) based minimization scheme and a non-iterative model back-projection (MBP) scheme for computing XACT reconstructions have been demonstrated in this paper. The proposed algorithms have been numerically validated and then employed to perform reconstructions from experimental measurements obtained from an XACT setup. While the commonly used back-projection algorithm produces limited-view and noisy artifacts in the region of interest, model-based LSQR minimization overcomes these issues. The model based algorithms also reduce the ring artifacts caused due to the non-uniformity response of the multichannel data acquisition. Using the model-based reconstruction algorithms, we are able to obtain reasonable XACT reconstructions for acoustic measurements of up to 120° view. Although the MBP is more efficient than the model-based LSQR algorithm, it provides only the structural information of the region of interest. Overall, it has been demonstrated that the model-based image reconstruction yields better image quality for XACT than the standard back-projection. Moreover, the combination of model-based image reconstruction with different regularization methods can solve the limited view problem for XACT imaging (in many realistic cases where the full-view dataset is unavailable) and hence pave the way for the future clinical translation.

Dose delivery uncertainty is a major concern in proton therapy, adversely affecting the treatment precision and outcome. Recently, a promising technique, proton-acoustic (PA) imaging, has been developed to provide real-time in vivo 3D dose verification. However, its dosimetry accuracy is limited due to the limited-angle view of the ultrasound transducer. In this study, we developed a deep learning-based method to address the limited-view issue in the PA reconstruction. A deep cascaded convolutional neural network (DC-CNN) was proposed to reconstruct 3D high-quality radiation-induced pressures using PA signals detected by a matrix array, and then derive precise 3D dosimetry from pressures for dose verification in proton therapy. To validate its performance, we collected 81 prostate cancer patients’ proton therapy treatment plans. Dose was calculated using the commercial software RayStation and was normalized to the maximum dose. The PA simulation was performed using the open-source k-wave package. A matrix ultrasound array with 64 × 64 sensors and 500 kHz central frequency was simulated near the perineum to acquire radiofrequency (RF) signals during dose delivery. For realistic acoustic simulations, tissue heterogeneity and attenuation were considered, and Gaussian white noise was added to the acquired RF signals. The proposed DC-CNN was trained on 204 samples from 69 patients and tested on 26 samples from 12 other patients. Predicted 3D pressures and dose maps were compared against the ground truth qualitatively and quantitatively using root-mean-squared-error (RMSE), gamma-index (GI), and dice coefficient of isodose lines. Results demonstrated that the proposed method considerably improved the limited-view PA image quality, reconstructing pressures with clear and accurate structures and deriving doses with a high agreement with the ground truth. Quantitatively, the pressure accuracy achieved an RMSE of 0.061, and the dose accuracy achieved an RMSE of 0.044, GI (3%/3 mm) of 93.71%, and 90%-isodose line dice of 0.922. The proposed method demonstrates the feasibility of achieving high-quality quantitative 3D dosimetry in PA imaging using a matrix array, which potentially enables the online 3D dose verification for prostate proton therapy.

Photoacoustic imaging (PAI) has enabled the high-resolution imaging of biological samples without reliance on external contrast agents. However, conventional photo- acoustic (PA) resolution in the axial direction is dependent on the maximum-detectable frequency of the ultrasound transducer, thereby limiting axial resolution to micrometers. Here, we present GHz detection of a PA signal that can potentially enhance the achievable resolution in PAI, previously limited by the detection bandwidth of ultrasound transducers. Our experimental setup shows that GHz detection of the PA signals is achievable via pump-probe imaging setups, which can enhance the axial resolution of PAI by orders of magnitude.

X-ray-induced acoustic computed tomography (XACT) is a promising imaging modality to monitor the position of the radiation beam and the deposited dose during external beam radiotherapy delivery. The purpose of this study was to investigate the feasibility of using a transperineal ultrasound transducer array for XACT imaging to guide the prostate radiotherapy. A customized two-dimensional (2D) matrix ultrasound transducer array with 10000 (100×100 elements) ultrasonic sensors with a central frequency of 1 MHz was designed on a 5 cm×5 cm plane to optimize three-dimensional (3D) volumetric imaging. The CT scan and dose treatment plan for a prostate patient undergoing intensity modulated radiation therapy (IMRT) were obtained. In-house simulation was developed to model the time varying X-ray induced acoustic (XA) signals detected by the transperineal ultrasound array. A 3D filtered back projection (FBP) algorithm has been used for 3D XACT image reconstruction. Results of this study will greatly enhance the potential of XACT imaging for real time in vivo dosimetry during radiotherapy.

X-ray induced acoustic computed tomography (XACT) is a unique hybrid imaging modality that combines high X-ray absorption contrast with high ultrasonic resolution. X-ray radiography and computerized tomography (CT) are currently the gold standards for two-dimensional and three-dimensional imaging of skeletal tissues, though there are important properties of bone, such as elasticity and speed of sound, that these techniques cannot measure. Ultrasound is capable of measuring such properties, though current clinical ultrasound scanners cannot be used to image the interior morphology of bones because they fail to address the complicated physics involved for exact image reconstruction; bone is heterogeneous and composed of layers of both cortical and trabecular bone, which violates assumptions in conventional ultrasound imaging of uniform speed of sound. XACT, in conjunction with the time-reversal algorithm, is capable of generating precise reconstructions, and, by combining elements of both X-ray and ultrasound imaging, XACT is potentially capable of obtaining more information than any single of these techniques at low radiation dose. This paper highlights X-ray-induced acoustic detection through linear scanning of an ultrasound transducer and the time-reversal algorithm to produce the first-ever XACT image of a bone sample. Results of this study should prove to enhance the potential of XACT imaging in the evaluation of bone diseases for future clinical use.

Electroporation is a technique that uses short-duration (nanosecond to microsecond) high-voltage electric pulses to create temporary pores in cell membranes or irreversibly destroys target cells for cancer treatment. The versatility of electroporation makes the technique ideal for direct drug delivery and cancer treatment. Electroacoustic tomography (EAT) is a novel imaging modality for electroporation treatment monitoring, that utilizes the existing energy deposited by highvoltage electrical fields created in the electroporation process. In EAT, ultrasound waves are generated by the deposited electric potential energy and captured by different configurations of ultrasound transducers. After being captured, the ultrasound information is used to reconstruct the geometric information of the electric field distribution in the target medium. In this work, we demonstrate the feasibility of electroacoustic tomography (EAT) by creating a 2D reconstruction of an electric field in the water. A custom high-voltage electric pulse generating device was made for delivering nanosecond duration pulses in water through two electrodes. A 500Khz ultrasound transducer was placed near the electrodes and rotated to capture the acoustic information from 180 positions. The corresponding 2D reconstruction of the electric field in water was completed by using filtered back-projection algorithm. The successful reconstruction of the electrical field in water marks the important step of EAT development for in-situ electroporation monitoring.

X-ray induced acoustic computed tomography (XACT) as a novel imaging modality has shown great potential in applications ranging from biomedical imaging to nondestructive testing. Improve the signal to noise ratio and removing the artifacts are major challenges in XACT imaging. We introduce an efficient non-uniformity correction method for the ultrasound ring transducer. Non-uniformity appears as ring artifacts in the reconstructed image when all sensor elements have a simultaneous time-variant response during the acquisition. Also, non-uniformity causes a contrast change effect in the reconstructed image when some defective sensor elements have a different response than the neighbors over the whole scan time. These two types of non-uniformity appear as horizontal or vertical strip patterns in sinogram domain based on the reason. The proposed method is a sinogram-based-algorithm, which is based on estimating a correction vector and localizing the abnormalities to compensate for the non-uniformity response. We applied the proposed algorithm on simulation data. The results have shown that the proposed method can greatly reduce the ring artifacts and also correct the distortion comes from sensor elements non-uniform response. Despite the great reduction of artifacts, the proposed method does not compromise the original spatial resolution and contrast after using the interpolation. The quantitative analysis has shown a great improvement in the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), while the normalized absolute error (NAE) has been reduced by 77–80 %.

We present a time-domain, model-based scheme for X-ray induced acoustic tomography (XACT). In comparison to the commonly used analytic schemes, the model-based reconstructions exhibit less limited-view and noisy artifacts and enable incorporating detector sizes and sound speed variations. In this paper, we brie y compare the performance of the proposed model-based scheme with the universal back-projection and model back-projection reconstructions obtained for full- and limited view test-cases in spherical detection geometry for noisy acoustic measurements. The algorithm has also been validated for experimental ring-array XACT data.

X-ray imaging has proved invaluable in medical diagnoses and non-destructive testing (NDT) in the past century. However, there remain two major limitations: radiation harm and inaccessibility to the sample. A recent imaging modality, X-ray induced acoustic computed tomography (XACT), allows a novel solution. In XACT, x-ray induced excitation causes localized heating (

This paper presents a photoacoustic non-destructive evaluation (pNDE) system with an ultrahigh resolution for the detection of multi-scale damage in carbon fiber-reinforced plastic (CFRP) composites. The pNDE system consists of three main components: a picosecond pulsed laser-based ultrasonic actuator, an ultrasound receiver, and a data acquisition/computing subsystem. During the operation, high-frequency ultrasound is generated by pulsed laser and recorded by an ultrasound receiver. By implementing a two-dimensional back projection algorithm, pNDE images can be reconstructed from the recorded ultrasound signals to represent the embedded damage. Both potential macroscopic and microscopic damages, such as surface notches and delamination in CFRP, can be identified by examining the reconstructed pNDE images. Three ultrasonic presentation modes including A-scan, B-scan, and C-scan are employed to analyze the recorded signals for the representation of the detected micro-scale damage in two-dimensional and three-dimensional images with a high spatial resolution of up to 60 &micro, m. Macro-scale delamination and transverse ply cracks are clearly visualized, identifying the edges of the damaged area. The results of the study demonstrate that the developed pNDE system provides a non-destructive and robust approach for multi-scale damage detection in composite materials.

Bone disease is a growing epidemic in the world today that will lead to billions of dollars of medical bills. While a range of lifestyle and genetic factors play a role in the progression of disease, in overarching symptom of increased bone porosity leads to decreased mobility, pain, fracture, and even death. Therefore, it is important to monitor trabecular bone for better care of affected individuals. Photoacoustic microscopy (PAM) is a hybrid modality that combines high optical absorption qualities of biological tissue with high spatial resolution of ultrasound. Our study aims to further assess the ability to image bone microarchitecture with photoacoustic imaging. A picosecond-pulsed laser with a wavelength of 532 nm was used to excite the bone while ultrasonic transients were captured by a 20 MHz transducer. We first preformed studies to characterize our lateral resolution and optimize our system using phantoms mimicking different bone porosity. We then imaged pig bone ex-vivo. Our results show that this photoacoustic (PA) imaging has the potential to identify normal and osteoporosis diseased bone. The capability to noninvasively quantify bone tissue composition suggests a possible use of PAM as an optical biopsy for the diagnosis of bone pathologies such as osteoporosis, which are characterized by a progressive reduction and transformation of mineral in the bone matrix.

Purpose The objective of this study is to demonstrate the feasibility of x-ray-induced acoustic computed tomography (XACT) for early breast un-palpable microcalcification (μCa) detection in three dimensions (3D). The proposed technique provides the true 3D imaging for breast volume which overcomes the disadvantage of the tissue superposition in mammography. Methods A 3D breast digital phantom was rendered from two-dimensional (2D) breast CT slices. Three different tissue types, including the skin, adipose tissue, and glandular tissue, were labeled in the 3D breast phantom. μCas were manually embedded in different locations inside the breast phantom. For each tissue type, the initial pressure rise caused by the x-ray-induced acoustic (XA) effect was calculated according to its themoacoustic properties. The XA wave's propagation from the point of generation and its detection by ultrasound detector array were simulated by Matlab K-Wave toolbox. The 3D breast XACT volume with μCa was acquired without tissue superposition, and the system was characterized by μCas placed at different locations. Results The simulation results illustrated that the proposed breast XACT system has the ability to show the μCa cluster in 3D without any tissue superposition. Meanwhile, μCa as small as 100 μm in size can be detected with high imaging contrast, high signal to noise ratio (SNR), and high contrast to noise ratio (CNR). The dose required by the proposed XACT configuration was calculated to be 0.4 mGy for a 4.5 cm-thick compressed breast. This is one-tenth of the dose level of a typical two-view mammography for a breast with the same compression thickness. Conclusions The initial exploration for the feasibility of 3D breast XACT has been conducted in this study. The system feasibility and characterization were illustrated through a 3D breast phantom and simulation works. The 3D breast XACT with the proposed system configuration has great potential to be applied as a low-dose screening and diagnostic technique for early un-palpable lesion in the breast.

X-ray-induced acoustic computed tomography (XACT) has emerged as a promising imaging modality with broad applications in both biomedicine and nondestructive testing. The previous XACT imaging systems require thousands of averages to achieve reasonable images. Here, we report the experimental demonstration of single-shot XACT imaging of a metal object using a single-shot 50 ns x-ray pulse. A two-stage dedicated amplification and a 128-channel parallel data acquisition configuration were introduced for XACT imaging to enable sufficient acoustic signal amplification and maintain an overall low noise level for single-shot XACT imaging. Details of the system design are presented; the improved signal-to-noise ratio (>23 dB) and image reconstruction have been demonstrated with a ring ultrasound transducer array imaging system. The study paves the way for realizing real-time XACT imaging and its potential applications in image-guided intervention.

The feasibility of electroacoustic tomography (EAT) was investigated for in situ monitoring the electric field distribution in soft tissue. EAT exploits the phenomenon that the amplitude of acoustic emission generated by an electric field is proportional to the electrical energy deposition in tissue. After detecting these acoustic waves with ultrasound transducers, an image of the electric field distribution can be reconstructed in real-time. In our computer simulations, the electric field distribution in soft tissue was generated by solving general partial differential equations (PDEs) using finite element analysis (FEA). The electric field distributions were converted into initial pressure distributions, and the propagation of the induced acoustic waves was simulated using K-Wave simulation. A circular array of 128 ultrasound transducers was placed around the target to detect the acoustic waves, and a time reversal reconstruction algorithm was used to reconstruct the EAT image. A different number of electrodes set at different distances with different voltage inputs on the electrodes were performed to simulate different electric field distributions during electroporation. It was found that the electrical energy deposition in reconstructed EAT imaging is decreased as the distance of the electrodes increases. We also have investigated the sensitivity of the EAT imaging with different voltage inputs. The minimal voltage we can detect with EAT is 970 V at the pulsewidth of 180 ns. The results of this study demonstrated that EAT is a feasible technique for monitoring the electric field distribution and guiding the electrotherapy in future clinical practice.

For decades, aircraft disasters have always been a concern for airline companies and especially for consumers. Scientists all over the world have been constantly trying to study, discover and invent new methods for testing and prevention to reduce future aircraft accidents. One of those methods is non-destructive testing, which is a widely adaptive process for analyzing structural integrity over wide arrays of object. X-rays, ultrasound and computed tomography (CT) are non-destructive testing applications commonly used for the commercial aircraft maintenance. These non-destructive testing methods for aircraft structures give us high-quality images of structural damage but, there are some disadvantages related to resolution and the contrast mechanism of the image. The goal of this study is to demonstrate the concept of X-Ray Induced Acoustic Computed Tomography (XACT) imaging method for defect detection and localization through simulations using k-wave MATLAB toolbox. XACT is a technique based on the X-ray induced acoustic effect. In XACT, a short pulsed of X-rays are required to achieve thermal response and generate acoustic waves. X-ray travels to an object, the photons are absorbed causing the temperature in the object to raise, which generates acoustic waves due to thermoelastic expansion. These acoustic waves are then detected by ultrasonic transducers. Within the fuselage of the aircraft, the aircraft’s stiffener is designed using SolidWorks. along with two different types of defects through voids due to manufacturing imperfection process. As well as, cracks in the surface of the model due to mechanical failures are created in MATLAB. Two properties of Aluminum 6065 and Inconel 625 materials were selected for our simulation study since it is often used for the fuselage and/or aircraft engines. XACT images are generated under the combination of high X-ray absorption and ultrasonic transducers that will be able to overcome the disadvantages of the X-ray imaging technique and ultrasound imaging technique in image resolution and contrast mechanisms. The results from this simulation study demonstrate that the XACT method not only gives us high-resolution images but moreover, higher contrast of images that also allows us to detect position accuracy of the cons created.

In our experiments, a technique has been developed to simultaneously acquire Electroacoustic (EA) signal captured by a single channel ultrasonic traducer in a linear array structure. The system utilizes micro- to nano-second pulsed electric field applied by an excitation source that can be used for clinical purposes (i.e. electroporation applications), and a conventional ultrasound transducer to acquire pulse electric field-induced acoustic signals. In this research, for the first time, we present a new real-time imaging-based technique when applying different electric field distributions that disturb electrically charged particles in the media that leads to a change of temperature which increases on the order of mK per a single high intensive, μ𝑠 −𝑛𝑠 short-pulse. We demonstrated this new technique by acquiring real-time acoustic signals induce by electric field distribution inside an agar-conductive based phantom. We used low-noise-amplifiers with a maximum gain of 60dB at 500 kHz with a linear scanning structure within less than 20sec, in 500 steps, and delay time of 500 ms to stabilize the transducer, and establish a linear scanning with a single element transducer. The corresponding EA images are reconstructed with a multi-step line back-projection algorithm. The approach can effectively reduce the artifacts associated with a conventional filter back projection algorithm used in other ultrasonic imaging by linear scanning structure because it is able to take information at multiple points to deliver the best possible image. This EAT technique provides a new and unique imaging approach for realtime, in-situ electrotherapy-based clinical practical applications.

The design, fabrication, and performance of pre-screening tool using bioelectrical tissue profile is described. A probe of 8 electrodes using active-probe-sensing (AP-sensing) module was linearity distortion in the frequency response bonded to the 8 sub-regions of the breast surface forming the Bioimpedance transfer measurement system. Each measurement channel acquired the data from 1/8 of breast according to each breast defined in 8 sub-regions with split current injection channel and response behavioural bioelectricity detection. For this tissue bioelectrical measurement system, the electrodes were placed on the breast surface and before the bioelectrical profile were measured, we investigated a closed loop technique to compensate for the effects and measure the channel-skin-contact impedance. The AP-sensing module and connecting pads could be placed in the measurement electrode-Bras according to different breast size, and all measurement sub-regions should be equivalent for each case, but could be different in scale of 1- 2cm in related to different breast size. Bilateral structure was applied to compare each breast tissue bioelectrical properties in related to tissue behavioural in different frequency. Bioelectrical measurement efficiency was evaluated by the use of bioelectrical plots equivalent to a theoretical plot of the pure tissue profile versus average intracellular and extracellular and admittance behavioural of breast tissue able to flow electric field using Cole-Cole structure tissue modelling as a well-known bioelectrical tissue profile. The bioelectrical tissue profile as a pre-screening tool using theoretical pure tissue profiles and experimental measurements were evaluated in related a conventional Bioimpedance spectroscopy instruments. Breast bioelectrical profile of different breast density categories and average measurement values were significant, according to exist of fibro-glandular tissues in the total breast volume. The different of the theoretical values corresponding to pure fatty and fibro-glandular breast tissue behaviour was slightly different with the experimental measurements. We demonstrated the bioelectrical profile of breast tissue and extracting bioelectrical features that comparing in a bilateral structure to apply bioelectrical features as a supplementary data in the machine learning algorithms and present correspond risk factor for susceptibility of breast cancer in future studies. The preliminary equivalent theoretical and experimental results, evaluate the possibility of this new, non-imaging and label-free quantitative technique.

Novel cubic aggregated CoFe2O4 nanoparticles are successfully synthesized by hydrothermal method. Electrochemical results show that the CoFe2O4 nanoparticles exhibit good cycling performance and excellent rate capability. The first discharge and charge capacities of these nanoparticles are 1672.8 mAh g−1 and 1309.1 mAh g−1, respectively, with an initial coulombic efficiency of 78.3%. The electrode can retain a high capacity of 1133.5 mAh g−1 after 120 cycles at a current density of 100 mA g−1. Moreover, it could still maintain a reversible capacity of 679 mAh g−1 even at a high current density of 3.2 A g−1. The improved electrochemical performance can be ascribed to the hierarchical cubic aggregated structural with large specific surface area and lots of interspaces between the particles, which not only can effectively increase the active surface area, but also can make better penetration of the electrolyte and accommodate the volume expansion.

In this Letter, we propose a novel triplex-parameter detection method to realize simultaneous radiometric, photoacoustic, and ultrasonic imaging based on single-pulse excitation. The optical attenuation, optical absorption, and acoustic impedance properties can be obtained simultaneously by analyzing the photoacoustic signals and the ultrasonic echo signals. To test the feasibility and accuracy of this method, agar phantoms with different absorption coefficients and elastic coefficients were measured. Then, this method was experimentally verified by imaging a leaf skeleton piece embedded in an agar cylinder. Furthermore, pilot experiments were performed by triplex imaging of pig ear tissue ex vivo to characterize the cartilage and surrounding tissue. Experimental results demonstrated that this technique has future potentials for visualizing and providing the functional and structural information of biological tissues.

Damage precursor in composites can lead to large structural damages, such as delamination, in carbon fiber reinforced plastic (CFRP) composites due to complex load conditions and environmental effects. In addition, multiple types of damage precursors including micro-scale matrix cracks, fiber pull-out from matrix, and fiber breakages, are extremely difficult to detect due to the limitation of resolution of current non-destructive evaluation (NDE) technologies. This paper presents a photo-acoustic based non-contact NDE system for the detection of damage precursors with extremely high resolution up to one hundred micrometers. This system consists of three major components: picoseconds pulsed laser based ultrasonic actuator, ultrasound receiver, and data processing and computing subsystem. Picoseconds pulsed laser is used to generate ultrasonic propagations in composites during the NDE process, and the ultrasound signals are recorded by the ultrasound receiver. Three-dimensional microstructure of the individual composites grid within the composite is able to be reconstructed for further analysis. The size and position of the damage precursors are evaluated with high accuracy up to 100 μm. The experimental results demonstrate that this imaging system is able to provide a novel non-contact approach with extremely high resolution for damage detection of CFRP composites. In addition, the developed NDE system has a wide industrial application in aerospace, automobile, civil, mechanical, and other key industries.

We proposed polarized photoacoustic microscopy (PPAM) for quantitative detection of a target’s microscopic anisotropy based on the vectorial optical absorption by applying four linearly polarized laser beams as excitation sources. Compared to conventional photoacoustic microscopy that treats targets as isotropic absorbers, PPAM allows us to quantitatively detect the target’s anisotropic features beyond optical absorption with a newly proposed parameter valued between 0 and 1. The feasibility of the method was validated by dichroic phantoms. The dichroic compound eyes of mantis shrimps were imaged in situ to demonstrate the method’s capability for quantitative three-dimensional biological imaging. The PPAM method provides an effective and straightforward strategy for tissue polarimetry, prefiguring great potential for biological imaging and material inspection.

The objective of this study is to develop and test a unique portable device that aims to non-invasively detect bio-electrochemical characteristics of human tissues. For this purpose, we designed and developed a new portable Bio-impedance Spectroscopy (BIS) system utilizing active probe technique as measurement technique for bioelectrical features. This BIS system includes the integrated current source and output voltage signal detection sensors. Active probes are placed on the skin surface of the targeted human organ tissues to directly detect bioimpedance signals. Bio-impedance spectrum was measured by applying electrical currents over a range of frequencies (10kHz − 3MHz). The spectrum was then quantitatively analyzed to produce new biomarkers based on bio-electrochemical characteristics of human tissues. These new bioelectrical markers aim to accurately and reproducibly predict and/or detect human diseases (including cancer). To address the feasibility of this new research technique, we conducted a comprehensive evaluation of new BIS device with its calibration techniques and phantom study. Results showed that the computed bioelectrical marker values monotonically change corresponding to tissue compositions. In this research, we demonstrated how to compute independent and dependent bioelectrical features to be implemented on machine learning (ML) models that can improve our understanding of disease or cancer risk state. The study suggested that using this new device has potential for different applications, including the noninvasive assessment of breast density and the detection of asymmetrical focal areas between two bilateral breasts, which may eventually help more accurately predict breast cancer risk.

The use of nanoporation in reversible or irreversible electroporation, e.g. cancer ablation, is rapidly growing. This technique uses an ultra-short and intense electric pulse to increase the membrane permeability, allowing non-permeant drugs and genes access to the cytosol via nanopores in the plasma membrane. It is vital to create a real-time in situ monitoring technique to characterize this process and answer the need created by the successful electroporation procedure of cancer treatment. All suggested monitoring techniques for electroporation currently are for pre-and post-stimulation exposure with no real-time monitoring during electric field exposure. This study was aimed at developing an innovative technology for real-time in situ monitoring of electroporation based on the typical cell exposure-induced acoustic emissions. The acoustic signals are the result of the electric field, which itself can be used in realtime to characterize the process of electroporation. We varied electric field distribution by varying the electric pulse from 1μ - 100ns and varying the voltage intensity from 0 − 1.2 to energize two electrodes in a bi-polar set-up. An ultrasound transducer was used for collecting acoustic signals around the subject under test. We determined the relative location of the acoustic signals by varying the position of the electrodes relative to the transducer and varying the electric field distribution between the electrodes to capture a variety of acoustic signals. Therefore, the electric field that is utilized in the nanoporation technique also produces a series of corresponding acoustic signals. This offers a novel imaging technique for the real-time in situ monitoring of electroporation that may directly improve treatment efficiency.

A multi-frequency Electrical Impedance Mammography (EIM) system has been developed to evaluate the conductivity and permittivity spectrums of breast tissues, which aims to improve early detection of breast cancer as a non-invasive, relatively low cost and label-free screening (or pre-screening) method. Multi-frequency EIM systems typically employ current excitations and measure differential potentials from the subject under test. Both the output impedance and system performance (SNR and accuracy) depend on the total output resistance, stray and output capacitances, capacitance at the electrode level, crosstalk at the chip and PCB levels. This makes the system design highly complex due to the impact of the unwanted capacitive effects, which substantially reduce the output impedance of stable current sources and bandwidth of the data that can be acquired. To overcome these difficulties, we present new methods to design a high performance, wide bandwidth EIM system using novel second generation current conveyor operational amplifiers based on a gyrator (OCCII-GIC) combination with different current excitation systems to cancel unwanted capacitive effects from the whole system. We reconstructed tomography images using a planar E-phantom consisting of an RSC circuit model, which represents the resistance of extra-cellular (R), intra-cellular (S) and membrane capacitance (C) of the breast tissues to validate the performance of the system. The experimental results demonstrated that an EIM system with the new design achieved a high output impedance of 10MΩ at 1MHz to at least 3MΩ at 3MHz frequency, with an average SNR and modelling accuracy of over 80dB and 99%, respectively.

Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380more » kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 10{sup 6} per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range verification may be feasible with approximately 5 × 10{sup 6} protons/pulse and beam current.« less

Photoacoustic therapy using the large photoacoustic effect of agents for selectively killing cancer cells is demonstrated. Herein, a highly efficient photoacoustic treatment using gold nanorods (AuNRs) and its antitumor effect are reported. Folic acid conjugated AuNRs are designed to specifically target folate receptor-expressing cancer cells. Following photoacoustic treatment, most of the cancer cells with intracellular AuNRs die within 20s. Compared with single-walled carbon nanotubes and indocyanine green containing nanoparticles, AuNRs can produce much stronger shock waves by absorbing the optical energy and thus induced the more efficient cell death at equal molar concentrations. In addition, the laser-induced shock waves can be detected for photoacoustic imaging. Our in vivo experiments demonstrated that the AuNR-mediated photoacoustic treatment resulted in efficient tumor suppression in mice. Thus, both efficient cancer cell diagnostics and selective photoacoustic treatment can be realized with a single-particle formulation. From the Clinical Editor Nanotechnology has enabled the development of many novel methods for the treatment of cancer. One of these is photoacoustic therapy. In this article, the authors demonstrated the efficacy of Folic acid conjugated gold nanorods in killing cancer cells after photoacoustic treatment. The findings should provide impetus for future clinical studies.