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In this paper, we demonstrate that spintronic microwave sensors have the capability to perform microwave imaging. The detection of the amplitude and phase of a scattered microwave signal over a wide frequency band allows this technique to determine the time delay of a microwave signal scattered by the target. Combining microwave radar techniques and a wavefront reconstruction algorithm with a spintronic microwave sensor in circular trajectory, the reconstructed images of targets are obtained. The reconstructed images clearly indicate the targets' positions even when the targets were immersed in a liquid to simulate an inhomogeneous tissue environment. Such a technique provides a promising approach for microwave imaging, with the potential for biomedical applications. [ABSTRACT FROM AUTHOR]

A microwave tomography imaging system, which uses a hybrid binary-real genetic algorithm (GA) is described in this work. This method utilizes global optimization for solving the inverse scattering problem based on hybrid version of GA, which is the combination of both real and binary-coded GA. This method is principally aimed at breast imaging for the detection of malignant tumors. The proposed technique is based on a time-domain inverse solver, which uses the multi-illumination technique and includes the dispersive and heterogeneous characteristic of the breast tissues. In this algorithm, real-coded GA acts as a regularizer for binary-coded GA and rejects the non-true solutions. The proposed technique is validated using a numerical breast phantom created based on magnetic resonance imaging (MRI) of actual patients. The results are compared with non-hybrid binary and real GAs and the superior efficiency of the proposed method over the methods that solely employ real or binary GA is illustrated. [ABSTRACT FROM AUTHOR]

This paper investigates the feasibility and accuracy of using a computer vision algorithm and electronic portal images to track the motion of a tumour-like target from a breathing phantom. A multi-resolution optical flow algorithm that incorporates weighting based on the differences between frames was used to obtain a set of vectors corresponding to the motion between two frames. A global value representing the average motion was obtained by computing the average weighted mean from the set of vectors. The tracking accuracy of the optical flow algorithm as a function of the breathing rate and target visibility was investigated. Synthetic images with different contrast-to-noise ratios (CNR) were created, and motions were tracked. The accuracy of the proposed algorithm was compared against potentiometer measurements giving average position errors of 0.6 ± 0.2 mm, 0.2 ± 0.2 mm and 0.1 ± 0.1 mm with average velocity errors of 0.2 ± 0.2 mm s-1, 0.4 ± 0.3 mm s-1 and 0.6 ± 0.5 mm s-1 for 6, 12 and 16 breaths min-1 motions, respectively. The cumulative average position error reduces more rapidly with the greater number of breathing cycles present in higher breathing rates. As the CNR increases from 4.27 to 5.6, the average relative error approaches zero and the errors are less dependent on the velocity. When tracking a tumour on a patient's digitally reconstructed radiograph images, a high correlation was obtained between the dynamically weighted optical flow algorithm, a manual delineation process and a centroid tracking algorithm. While the accuracy of our approach is similar to that of other methods, the benefits are that it does not require manual delineation of the target and can therefore provide accurate real-time motion estimation during treatment. [ABSTRACT FROM AUTHOR]

A far-field microwave imaging technique has been developed using a spintronic sensor based on a magnetic tunnel junction (MTJ). Such a sensor can directly rectify a microwave field into a dc voltage signal using the Seebeck effect. Thanks to the high conversion efficiency of the microwave rectification in MTJs, the microwave power sensitivity of the spintronic sensor is on the order of 1-10 mV/mW. This high sensitivity allows the sensor to directly measure the coherent spatial scattered microwave field distribution, which gives it the ability to non-destructively detect hidden objects down to a few wavelengths in size. [ABSTRACT FROM AUTHOR]

During the last decade, radar imaging has been used in near-field scenarios where a cylindrical scan geometry is required to properly illuminate the scan region, such as breast microwave radar imaging and microwave wood inspection. Nevertheless, current cylindrical near-field radar image formation algorithms are not fast enough to provide the throughput required by these novel applications. A real-time wavefront reconstruction approach for the formation of three-dimensional cylindrical near-field radar images is proposed in this study. This technique parallelises the mapping procedures during the reconstruction process in order to increase its computational efficiency. To further reduce the execution time of the proposed approach, it was implemented in a general purpose graphic processing unit in order to take advantage of the computing capabilities of this platform. The proposed method yielded accurate results when applied to simulated and experimental data sets and yielded speed improvements of two orders of magnitude compared to conventional cylindrical near-field radar reconstruction approaches. [ABSTRACT FROM AUTHOR]

Breast Microwave Radar (BMR) has been proposed as an alternative modality for breast imaging. This technology forms a reflectivity map of the breast region by illuminating the scan area using ultra wide band microwave waveforms and recording the reflections from the breast structures. Nevertheless, BMR images require to be interpreted by an experienced practitioner since the location and density of the breast region can make the detection of malignant lesions a difficult task. In this paper, a novel bimodal breast imaging reconstruction method based on the use of BMR and Electrical Impedance Tomography (EIT) is proposed. This technique forms an estimate of the breast region impedance map using its corresponding BMR image. This estimate is used to initialize an EIT reconstruction method based on the monotonicity principle. The proposed method yielded promising results when applied to MRI-derived numeric breast phantoms. [ABSTRACT FROM AUTHOR]

Design features of a reduced size coplanar waveguide (CPW) fed ultra wide band (UWB) taper arc wide slot antenna with impedance Band Width (BW) of 9.69 GHz have been illustrated. The antenna depicts satisfactory performance both on free space and when immersed in three different coupling materials for application in the experimental MI set up. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2607–2611, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24701 [ABSTRACT FROM AUTHOR]

A diamond-shaped compact, planar ultra-wide band (UWB) antenna with measured free-space frequency bandwidth of 3.80 to 11.85 GHz is presented. Design features for achieving UWB with small geometrical features and antenna performance in some coupling medium have been investigated to verify the feasibility of the antenna for medical imaging applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3255–3259, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23941 [ABSTRACT FROM AUTHOR]

Hereditary nonpolyposis colorectal cancer (HNPCC), clinically defined by the Amsterdam criteria, is caused by highly penetrant germ line mutations in DNA mismatch repair (MMR) genes, mostly in MLH1 and MSH2, infrequently in MSH6 und PMS2. Mutation carriers are at high cumulative risk (52-92%) for developing colorectal cancer (CRC), including syn- and metachronous colorectal carcinomas, with a younger age of onset compared with sporadic CRC. In addition, there is a remarkably increased risk in these mutation carriers for extracolonic carcinomas, especially for endometrial and ovarian carcinomas but also for gastric, ureter and renal pelvis and small bowel cancer. Therefore, the question arises if an individually tailored conception of treatment should be applied to HNPCC patients and mutation carriers. On principle, there are three options of surgical approach conceivable concerning the colorectum: i) prophylactic resection in healthy mutation carriers ii) oncological resection in the case of CRC iii) extended resection with an additional prophylactic intent in the case of first CRC. After critical evaluation of various arguments, the first option cannot be recommended for CRC prevention. However, a final recommendation neither for the second nor the third option of surgical approach can be given at the moment. The indication for a prophylactic hysterectomy and oophorectomy should be weighted in the following postmenopausal patients after intensive genetic, surgical and gynecologic counselling: patients fulfilling the Amsterdam II criteria or who have been identified as mutation carriers of a disease causing germ line mutation in one of the MMR genes and who have to be operated on due to another cause. A precise prediction of the individual risk and age of onset on the basis of the analysis of interactions between endogenous and exogenous modifying factors is the precondition for recommendations concerning individually tailored surveillance or prophylactic surgery. [ABSTRACT FROM AUTHOR]