Diffuse optical tomography (DOT) is showing promise for breast tumor detection by
estimating optical property coefficients of breast tissue. In our previous study, we have
successfully reconstructed the synthetic data into three-dimensional (3-D) images with a
cylindrical model. Thus, the work within this study develops a 3-D image reconstruction algorithm
of DOT with a breast-like model for screening breast tumor. Reconstruction results show that the
quality of reconstructed images can be effective for tumor screening.
We implemented a ring-scanning mechanism in a prostrate type for breast tumor detection. Reconstructed μa and μs′
images of multi-layers scanning are presented in good outcomes, showing it’s promising for the 3D scanning of breast.
We propose and implement three-dimensional (3-D) ring-scanning equipment for near-infrared (NIR) diffuse optical imaging to screen breast tumors under prostrating examination. This equipment has the function of the radial, circular, and vertical motion without compression of breast tissue, thereby achieving 3-D scanning; furthermore, a flexible combination of illumination and detection can be configured for the required resolution. Especially, a rotation-sliding-and-moving mechanism was designed for the guidance of source- and detection-channel motion. Prior to machining and construction of the system, a synthesized image reconstruction was simulated to show the feasibility of this 3-D NIR ring-scanning equipment; finally, this equipment is verified by performing phantom experiments. Rather than the fixed configuration, this addressed screening/diagnosing equipment has the flexibilities of optical-channel expansion for spatial resolution and the dimensional freedom for scanning in reconstructing optical-property images.
In this presentation, we demonstrate a working prototype of an optical breast imaging system using parallel-paddle architecture with dual-direction scanning, of which the designed module can be incorporated with a mammographic system for the acquisition of optical transmission and reflection information in both directions of up-down and down-up. Additionally, the scanning module enables to move with a designated pitch to accommodate varied breast size for acquiring adequate data to reconstruct the images. Currently, continuous-wave near infrared illumination modules are used for experimentation. The feasibility will be presented by phantom test.
Diffuse optical imaging (DOI) providing functional information of tissues has drawn great attention for the last two decades. Near infrared (NIR) DOI systems composed of scanning bench, opt-electrical measurement module, system control, and data processing and image reconstruction schemes are developed for the screening and diagnosis of breast tumors. Mostly, the scanning bench belonging to fixed source-and-detector configuration limits computed image resolution to an extent. To cope with the issue, we propose, design and implement a 3D prostrate ring-scanning equipment for NIR DOI with flexible combinations of illumination and detection, and with the function of radial, circular and vertical movement without hard compression of breast tissue like the imaging system using or incorporating with X-ray mammographic bench. Especially, a rotation-sliding-and-moving mechanism was designed for the guidance of source- and detection-channel movement. Following the previous justification for synthesized image reconstruction, in the paper the validation using varied phantoms is further conducted and 3D image reconstruction for their absorption and scattering coefficients is illustrated through the computation of our in-house coded schemes. The source and detection NIR data are acquired to reconstruct the 3D images through the operation of scanning bench in the movement of vertical, radial and circular directions. Rather than the fixed configuration, the addressed screening/diagnosing equipment has the flexibility for optical-channel expansion with a compromise among construction cost, operation time, and spatial resolution of reconstructed μa and μs’ images.
The design scheme of the source-and-detector arrangement of a ring-scanning-based near-infrared optical imaging system prior to the mechanical and optical construction is demonstrated. In terms of the effectiveness and efficiency of design, through the computation of image reconstruction for varied imaging configurations, the influences of the source-and-detector arrangement on the resulting images are evaluated and a formula to estimate the scanning time is provided. The basic idea of our design is to divide circular scanning into several zones, each of which includes n sources and l detectors; i.e., m zones and n sources along with l detectors per zone are defined in the design. Comparison is made among different imaging configurations where their contrast-to-noise ratio measures are evaluated and contrast-and-size detail resolution curves are depicted. Results show that the 2Z3S or 3Z3S configuration is the optimal design in terms of the time consumption of a complete scanning and the resolution of reconstructed optical-property images.
The study aims at developing an optical measurement module incorporated with an X-ray mammographic
system to obtain diffuse optical images (DOI) for the detection of breast tumors. Two goals steer the study: (1) to
enhance sensitivity and specificity of tumor detection through the use of functional DOI; and (2) to reduce radiation
exposure by using only one mammogram, instead of two, as structure information to compute optical-coefficient
images. A dual-direction (downward and upward) scanning device to project illuminated near infrared light with
multiple-channel switching for both sources and detectors was designed and constructed to obtain double information.
The designed and constructed NIR scanning module incorporates with GE Senographe 2000D to assist breast tumor
detection.
A promising method to achieve rapid convergence for image reconstruction is introduced for the continuous-wave near-infrared (NIR) diffuse optical tomography (DOT). Tomographic techniques are usually implemented off line and are time consuming to realize image reconstruction, especially for NIR DOT. Therefore, it is essential to both speed up reconstruction and achieve stable and convergent solutions. We propose an approach using a constraint based on a Lorentzian distributed function incorporated into Tikhonov regularization, thereby rapidly converging a stable solution. It is found in the study that using the proposed method with around five or six iterations leads to a stable solution. The result is compared to the primary method usually converging in ~25 iterations. Our algorithm rapidly converges to stable solution in the case of noisy (>20 dB) detected intensities.
A promising method achieving rapid convergence for image reconstruction is introduced for the
continuous-wave NIR-DOT. An approach employs a constraint based on Lorentzian distributed
function incorporated into Tikhonov regularization, thereby rapidly converging a stable solution.
For various size, location and contrast of imitated tumors, both numerical computation and experimental
validation were conducted to investigate and conclude diagnosis limitation of an NIR-DOI system.
We attempt to develop a systematic scheme through adopting high-pass filtering (HPF) to well resolve value-preserved images such as medical images. Our approach is derived from the Poisson maximum a posteriori superresolution algorithm employing the HP filters, where four filters are considered such as two low-pass-filter-combination based filters, wavelet filter, and negative-oriented Laplacian HP filter. The proposed approach is incorporated into the procedure of finite-element-method (FEM)-based image reconstruction for diffuse optical tomography in the direct current domain, posterior to each iteration without altering the original FEM modeling. This approach is justified with various HPF for different cases that breast-like phantoms embedded with two or three inclusions that imitate tumors are employed to examine the resolution performances under certain extreme conditions. The proposed approach to enhancing image resolution is evaluated for all tested cases. A qualitative investigation of reconstruction performance for each case is presented. Following this, we define a set of measures on the quantitative evaluation for a range of resolutions including separation, size, contrast, and location, thereby providing a comparable evaluation to the visual quality. The most satisfactory result is obtained by using the wavelet HP filter, and it successfully justifies our proposed scheme.
Near-infrared diffuse optical tomography (NIR DOT) for noninvasive tissue monitoring have been developed for nearly
two decades. The NIR imaging, however, suffers from low resolution due to the diffusive nature of the scattered light;
there are compelling reasons for merging high-resolution structural information from other imaging modalities with the
functional information attainable with NIR DOT. In this article, slight variation of the inclusion (tumor) in low contrast
of optical properties is estimated and investigated. We present that an initial study of using a structural a prioriknowledge in NIR tomography where absorption image reconstruction of the tested phantom is well defined with the aid
of a structural a priori knowledge obtained from other imaging modalities. This is advantageous compared to either
modality alone. As well, the reconstructed optical absorption coefficient is achieved more accurate near to be exact
value with incorporating the empirical updating information being proportional to the off-boundary distance but not size
of inclusion against the background. Numerical simulation is demonstrated on varied sizes, locations and contrast of the
inclusion. With the comparison between with or without a priori and empirical updating information, it is found that the
reconstructed optical properties are more accurate than the near-infrared imaging alone.
Diffuse optical tomography (DOT) is in an attempt to image the interior of human tissues. However, the NIR imaging
suffers from low resolution due to the diffusive nature of the scattered light, which results into poor reconstructed image
quality. Thus, the effort to improve the image quality remains in progress. The numerical simulation using high-pass
filtering incorporated into the finite-element-based diffusion equation to reconstruct tomographic images of optical
properties was performed where results reveal that several inclusions (tumors) can be well defined separately, thereby
demonstrating the ability to highly resolve the image of interest with the optimal high-pass filtering process.
The study aims at developing a near infrared (NIR) tomography imaging system using a single rotating source/detector scanning device, which will be working for diffuse optical tomography (DOT) on medical applications. Some influential factors in terms of the design of this scanning device and test phantoms are investigated such as the temporal stability, air-absorption, container influence, and radiance normalization, etc. Then, a heterogeneous microsphere phantom with an off-center inclusion is investigated. It is observed that the radiance deviation between the heterogeneous and the homogenous is shifting with the inclusion position accordingly. Through the previously-mentioned system calibration, the back projection method as widely applied in the computed tomography (CT) technique is used to reconstruct optical images which indicate the distribution of optical property of the test phantom.
In the research, the pseudo-model technique is proposed and implemented to simulate biological tissues under the framework of investigating near infrared (NIR) light propagating in diffusive media. The same optical characteristics inhere in the corresponding pseudo-models as in real tissues, where pseudo-models are constructed by using various volume densities of Intralipid. The pseudo-model technique proposed in the study has following advantages:
1.For the NIR tomography imaging system, the output signal from the real tissue may be too weak to be detected beyond the ability of current technologies. Thus, the pseudo-model is a viable alternative to cope with the limitation of the system in the measurement of real tissues.
2.Once the pseudo-model of a real tissue is decided, its optical properties can be investigated thoroughly. In addition, the initial estimates for the reconstruction of NIR optical property images can be selected adequately, and the image reconstruction algorithm can be modified accordingly with the information acquired from the pseudo-model.
In the experiment, a pseudo-model of the background with an inclusion is performed for real tissues of pork inserted by a bone. It is observed that 1 % v.d. and 3 % v.d. of Intralipids can replace the pork and the bone, respectively, and the characteristics of the pseudo-model proposed here are consistent with those of the real tissues. As part of conclusion, the use of the pseudo-model technique is a promising approach to mimicking real tissues, especially for some parts of human body unable to be detected effectively.
Diffuse optical tomography (DOT) using diffuse light, red or near-infrared (NIR) light, is in an attempt to image the interior of human tissues such as breasts, arms, etc. In the current design of our NIR tomography imaging system, the system uses a single rotating source/detector scanning device associated with an image reconstruction scheme. The device can dramatically save source- and detection-fiber-bundles, and offer promising measured radiance reflecting the optical properties of the test phantoms. Both source and detector can rotate on command with any pre-defined angles controlled by the computer. Additionally, an image reconstruction algorithm applied to the tomography scanning device in the DC domain is also implemented. The ability and performance of this image reconstruction algorithm are discussed and presented. Results reveal that inclusion (tumor) positions can be well defined and the spatial resolution is beyond 1:16, inclusion to background.
The research aims at developing an NIR tomography system using a single rotating source/detector scanning device associated with an image reconstruction scheme. Several simulation results concerning the phantom with one, two or three targets are presented. Additionally, the developed system is validated by a hemoglobin phantom inserted by another different volume density one.
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