UWB high-contrast robust tomographic imaging for medical applications

Guardiola, M.; Capdevila, S.; Blanch, S.; Romeu, J.; Jofre, L.

doi:10.1109/iceaa.2009.5297370

Cited by 16 publications

(11 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While most of these techniques use single frequency illumination, some broadband alternatives have been developed in recent years (see Ref. 72 and references therein). Hence, these imaging techniques could be used to evaluate the frequency response of the scattered fields at the voxel(s) containing the stent to monitor its structural integrity.…”

Section: E Final Considerationsmentioning

confidence: 99%

Microwave spectrometry for the evaluation of the structural integrity of metallic stents

et al. 2014

View full text Add to dashboard Cite

Purpose:To assess the feasibility of a method based on microwave spectrometry to detect structural distortions of metallic stents in open air conditions and envisage the prospects of this approach toward possible medical applicability for the evaluation of implanted stents. Methods: Microwave absorbance spectra between 2.0 and 18.0 GHz were acquired in open air for the characterization of a set of commercial stents using a specifically design setup. Rotating each sample over 360• , 2D absorbance diagrams were generated as a function of frequency and rotation angle. To check our approach for detecting changes in stent length (fracture) and diameter (recoil), two specific tests were performed in open air. Finally, with a few adjustments, this same system provides 2D absorbance diagrams of stents immersed in a water-based phantom, this time over a bandwidth ranging from 0.2 to 1.8 GHz.Results: The authors show that metallic stents exhibit characteristic resonant frequencies in their microwave absorbance spectra in open air which depend on their length and, as a result, may reflect the occurrence of structural distortions. These resonances can be understood considering that such devices behave like dipole antennas in terms of microwave scattering. From fracture tests, the authors infer that microwave spectrometry provides signs of presence of Type I to Type IV stent fractures and allows in particular a quantitative evaluation of Type III and Type IV fractures. Recoil tests show that microwave spectrometry seems able to provide some quantitative assessment of diametrical shrinkage, but only if it involves longitudinal shortening. Finally, the authors observe that the resonant frequencies of stents placed inside the phantom shift down with respect to the corresponding open air frequencies, as it should be expected considering the increase of dielectric permittivity from air to water. Conclusions:The evaluation of stent resonant frequencies provided by microwave spectrometry allows detection and some quantitative assessment of stent fracture and recoil in open air conditions. Resonances of stents immersed in water can be also detected and their characteristic frequencies are in good agreement with theoretical estimates. Although these are promising results, further verification in a more relevant phantom is required in order to foresee the real potential of this approach.

show abstract

Section: E Final Considerationsmentioning

confidence: 99%

Microwave spectrometry for the evaluation of the structural integrity of metallic stents

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Multi-frequency combination has been implemented in this algorithm as the summation of the magnitude of mono-frequency images. This solution is widely applicable and preserves the shape and size of reconstructed objects in cases where coherent combination does not work [5]. …”

Section: D Uwb Hybrid Focusing Image Reconstruction Algorithmmentioning

confidence: 99%

“…Up to now, most studies have been limited to the use of iterative schemes [3], which have a high computational cost. This opens the door to less computationally intensive algorithms such as ones based on linearizing approximations [4] or UWB Hybrid Focusing techniques [5]. In this paper a novel 3D UWB tomographic algorithm based in [4] applied to stroke detection is presented.…”

Section: Introductionmentioning

confidence: 99%

3D UWB tomography for medical imaging applications

Guardiola

Jofre

Romeu

2010

2010 IEEE Antennas and Propagation Society International Symposium

View full text Add to dashboard Cite

In this paper, a novel 3D UWB tomographic algorithm has been presented for brain hemorrhagic stroke detection. While 2D reconstructions are unable to distinguish between features at different heights, 3D reconstructions allow to obtain a complete representation of the brain and thus to differentiate them. A human brain model has been successfully reconstructed and the position of a blood vessel detected.Peer ReviewedPostprint (published version

show abstract

“…Radar imaging has been an increasing popular research topic due to its ability to show the internal structure of an object while remaining noninvasive [2,3]. In inverse synthetic aperture radar (ISAR), the radar antenna is fixed and the target is rotated or moved [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Precision Near-Field Reconstruction in the Time Domain via Minimum Entropy for Ultra-High Resolution Radar Imaging

2017

Remote Sensing

View full text Add to dashboard Cite

Ultra-high resolution (UHR) radar imaging is used to analyze the internal structure of objects and to identify and classify their shapes based on ultra-wideband (UWB) signals using a vector network analyzer (VNA). However, radar-based imaging is limited by microwave propagation effects, wave scattering, and transmit power, thus the received signals are inevitably weak and noisy. To overcome this problem, the radar may be operated in the near-field. The focusing of UHR radar signals over a close distance requires precise geometry in order to accommodate the spherical waves. In this paper, a geometric estimation and compensation method that is based on the minimum entropy of radar images with sub-centimeter resolution is proposed and implemented. Inverse synthetic aperture radar (ISAR) imaging is used because it is applicable to several fields, including medicaland security-related applications, and high quality images of various targets have been produced to verify the proposed method. For ISAR in the near-field, the compensation for the time delay depends on the distance from the center of rotation and the internal RF circuits and cables. Required parameters for the delay compensation algorithm that can be used to minimize the entropy of the radar images are determined so that acceptable results can be achieved. The processing speed can be enhanced by performing the calculations in the time domain without the phase values, which are removed after upsampling. For comparison, the parameters are also estimated by performing random sampling in the data set. Although the reduced data set contained only 5% of the observed angles, the parameter optimization method is shown to operate correctly.

show abstract

UWB high-contrast robust tomographic imaging for medical applications

Cited by 16 publications

References 10 publications

Microwave spectrometry for the evaluation of the structural integrity of metallic stents

Microwave spectrometry for the evaluation of the structural integrity of metallic stents

3D UWB tomography for medical imaging applications

Precision Near-Field Reconstruction in the Time Domain via Minimum Entropy for Ultra-High Resolution Radar Imaging

Contact Info

Product

Resources

About