Development of a digital breast phantom for photoacoustic computed tomography

BACKGROUND: The time of flight (TOF) cone beam computed tomography (CBCT) was recently shown to reduce the X-ray scattering effects by 95%and improve the image CNR by 110%for large volume objects. The advancements in X-ray sources like in compact Free Electron Lasers (FEL) and advancements in detector technology show potential for the TOF method to be feasible in CBCT when imaging large objects. OBJECTIVE: To investigate feasibility and efficacy of TOF CBCT in imaging smaller objects with different targets such as bones and tumors embedded inside the background. METHODS: The TOF method used in this work was verified using a 24cm phantom. Then, the GATE software was used to simulate the CBCT imaging of an 8 cm diameter cylindrical water phantom with two bone targets using a modeled 20 keV quasi-energetic FEL source and various TOF resolutions ranging from 1 to 1000 ps. An inhomogeneous breast phantom of similar size with tumor targets was also imaged using the same system setup. RESULTS: The same results were obtained in the 24cm phantom, which validated the applied CBCT simulation approach. For the case of 8cm cylindrical phantom and bone target, a TOF resolution of 10 ps improved the image contrast-to-noise ratio (CNR) by 57%and reduced the scatter-to-primary ratio (SPR) by 8.63. For the case of breast phantom and tumor target, image CNR was enhanced by 12%and SPR was reduced by 1.35 at 5 ps temporal resolution. CONCLUSIONS: This study indicates that a TOF resolution below 10 ps is required to observe notable enhancements in the image quality and scatter reduction for small objects around 8cm in diameter. The strong scattering targets such as bone can result in substantial improvements by using TOF CBCT.

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A Single Simulation Platform for Hybrid Photoacoustic and RF-Acoustic Computed Tomography

Applied Sciences ◽

10.3390/app8091568 ◽

2018 ◽

Vol 8 (9) ◽

pp. 1568 ◽

Cited By ~ 5

Author(s):

Christopher Fadden ◽

Sri-Rajasekhar Kothapalli

Keyword(s):

Computed Tomography ◽

Numerical Models ◽

Imaging Systems ◽

Reconstruction Algorithms ◽

Finite Element Software ◽

Thermoacoustic Imaging ◽

Electromagnetic Absorption ◽

Breast Phantom ◽

Molecular Information ◽

Absorption Contrast

In recent years, multimodal thermoacoustic imaging has demonstrated superior imaging quality compared to other emerging modalities. It provides functional and molecular information, arising due to electromagnetic absorption contrast, at ultrasonic resolution using inexpensive and non-ionizing imaging methods. The development of optical- as well as radio frequency (RF)-induced thermoacoustic imaging systems would benefit from reliable numerical simulations. To date, most numerical models use a combination of different software in order to model the hybrid thermoacoustic phenomenon. Here, we demonstrate the use of a single open source finite element software platform (ONELAB) for photo- and RF-acoustic computed tomography. The solutions of the optical diffusion equation, frequency domain Maxwell’s equations, and time-domain wave equation are used to solve the optical, electromagnetic, and acoustic propagation problems, respectively, in ONELAB. The results on a test homogeneous phantom and an approximate breast phantom confirm that ONELAB is a very effective software for both photo- and RF-acoustic simulations, and invaluable for developing new reconstruction algorithms and hardware systems.

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Coherence Factor-Like Beamforming for Ultrasound Computed Tomography

Journal of Medical Imaging and Health Informatics ◽

10.1166/jmihi.2020.2916 ◽

2020 ◽

Vol 10 (3) ◽

pp. 672-676

Author(s):

Shanshan Wang ◽

Liang Zeng ◽

Junjie Song ◽

Liang Zhou ◽

Mingyue Ding ◽

...

Keyword(s):

Computed Tomography ◽

Center Frequency ◽

Medical Ultrasound ◽

Practical Application ◽

Image Brightness ◽

Coherence Factor ◽

Ultrasound Computed Tomography ◽

Breast Phantom ◽

Black Region ◽

Type Transducer

Ultrasound computed tomography (USCT) has important clinical application prospect in breast cancer screening and early diagnosis. In this paper, six kinds of coherence factor-like beamforming methods have been applied to improve the image quality for USCT, including coherence factor (CF), phase coherence factor (PCF), sign coherence factor (SCF), phasor dispersion based coherence factor (PDCF), spatial smoothed coherence factor (SSCF) and spatio-temporally smoothed coherence factor (STSCF). The mentioned methods were verified with the radio-frequency (RF) data of the breast phantom captured by the USCT system developed in the Medical Ultrasound Laboratory. The ring-type transducer has 1024 elements with a center frequency of 2.5 MHz. Experimental results show that the reconstructed images of the breast phantom by the CF gets the highest contrast to noise ratio (CNR), but overall image brightness reduces significantly. PCF gets the lowest variance and provides a more homogenous background. STSCF beamforming method can improve the robustness of the PCF and having the ability to suppress clutter while significant removal of black region artifacts. For practical application, these coherence factor-like beamforming methods can be implemented with low computational complexity.

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X-ray microtomography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107058 ◽

1988 ◽

Vol 46 ◽

pp. 998-999

Author(s):

H.W. Deckman ◽

B.F. Flannery ◽

J.H. Dunsmuir ◽

K.D' Amico

Keyword(s):

Computed Tomography ◽

Internal Structure ◽

Imaging Technique ◽

Three Dimensional ◽

Tissue Structure ◽

Individual Element ◽

X Ray ◽

Non Invasive ◽

Panoramic Imaging ◽

Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

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