| 1. |
- Candefjord, Stefan, 1981, et al.
(författare)
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A wearable microwave instrument can detect and monitor traumatic abdominal injuries in a porcine model
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Abdominal injury is a frequent cause of death for trauma patients, and early recognition is essential to limit fatalities. There is a need for a wearable sensor system for prehospital settings that can detect and monitor bleeding in the abdomen (hemoperitoneum). This study evaluates the potential for microwave technology to fill that gap. A simple prototype of a wearable microwave sensor was constructed using eight antennas. A realistic porcine model of hemoperitoneum was developed using anesthetized pigs. Ten animals were measured at healthy state and at two sizes of bleeding. Statistical tests and a machine learning method were used to evaluate blood detection sensitivity. All subjects presented similar changes due to accumulation of blood, which dampened the microwave signal (p< 0.05). The machine learning analysis yielded an area under the receiver operating characteristic (ROC) curve (AUC) of 0.93, showing 100% sensitivity at 90% specificity. Large inter-individual variability of the healthy state signal complicated differentiation of bleedings from healthy state. A wearable microwave instrument has potential for accurate detection and monitoring of hemoperitoneum, with automated analysis making the instrument easy-to-use. Future hardware development is necessary to suppress measurement system variability and enable detection of smaller bleedings.
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| 2. |
- Guerrero Orozco, Laura, 1996, et al.
(författare)
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Microwave Antenna System for Muscle Rupture Imaging with a Lossy Gel to Reduce Multipath Interference
- 2022
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 22:11
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Tidskriftsartikel (refereegranskat)abstract
- Injuries to the hamstring muscles are an increasing problem in sports. Imaging plays a key role in diagnosing and managing athletes with muscle injuries, but there are several problems with conventional imaging modalities with respect to cost and availability. We hypothesized that microwave imaging could provide improved availability and lower costs and lead to improved and more accurate diagnostics. In this paper, a semicircular microwave imaging array with eight antennae was investigated. A key component in this system is the novel antenna design, which is based on a monopole antenna and a lossy gel. The purpose of the gel is to reduce the effects of multipath signals and improve the imaging quality. Several different gels have been manufactured and evaluated in imaging experiments. For comparison, corresponding simulations were performed. The results showed that the gels can effectively reduce the multipath signals and the imaging experiments resulted in significantly more stable and repeatable reconstructions when a lossy gel was used compared to when an almost non-lossy gel was used.
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| 3. |
- Guerrero Orozco, Laura, 1996, et al.
(författare)
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Muscle Rupture Microwave Imaging with a Lossy Gel to Reduce Multipath Interference
- 2023
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Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
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Konferensbidrag (refereegranskat)abstract
- Imaging can make a difference in the diagnosis and management of athletes with muscle injuries, especially muscle injuries in the hamstring muscles where they commonly happen. Unfortunately, muscle injuries are often not diagnosed due to the cost and availability problems encountered when using conventional imaging methods. Microwave imaging could bring a solution to this problem and improve availability at lower costs. We have earlier presented a semicircular microwave imaging system made of monopole antennas embedded in lossy gel. The purpose of the lossy gel was to reduce direct coupling between antennas and thereby improve image reconstruction accuracy. In this work, we expanded the previous work by exploring different positions and object sizes of blood phantom targets immersed in a muscle phantom. The results showed that the reconstruction results were significantly more repeatable and accurate regardless of object size and position when a lossy gel was used instead of a non-lossy gel.
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| 4. |
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| 5. |
- Hosseinzadegan, Samar, 1987, et al.
(författare)
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Discrete Dipole Approximation-Based Microwave Tomography for Fast Breast Cancer Imaging
- 2021
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 69:5, s. 2741-2752
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Tidskriftsartikel (refereegranskat)abstract
- This article describes a fast microwave tomography reconstruction algorithm based on the 2-D discrete dipole approximation (DDA). Synthetic data from a finite-element-based solver and experimental data from a microwave imaging system are used to reconstruct images and to validate the algorithm. The microwave measurement system consists of 16 monopole antennas immersed in a tank filled with lossy coupling liquid and a vector network analyzer. The low-profile antennas and lossy nature of the system make the DDA an ideal forward solver in image reconstructions. The results show that the algorithm can readily reconstruct a 2-D plane of a cylindrical phantom. The proposed forward solver combined with the nodal adjoint method for computing the Jacobian matrix enables the algorithm to reconstruct an image within 6 s. This implementation provides significant time savings and reduced memory requirements and is a dramatic improvement over previous implementations.
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| 6. |
- Hosseinzadegan, Samar, 1987, et al.
(författare)
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Expansion of the nodal-adjoint method for simple and efficient computation of the 2d tomographic imaging jacobian matrix
- 2021
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 21:3, s. 1-16
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper focuses on the construction of the Jacobian matrix required in tomographic reconstruction algorithms. In microwave tomography, computing the forward solutions during the iterative reconstruction process impacts the accuracy and computational efficiency. Towards this end, we have applied the discrete dipole approximation for the forward solutions with significant time savings. However, while we have discovered that the imaging problem configuration can dramatically impact the computation time required for the forward solver, it can be equally beneficial in constructing the Jacobian matrix calculated in iterative image reconstruction algorithms. Key to this implementation, we propose to use the same simulation grid for both the forward and imaging domain discretizations for the discrete dipole approximation solutions and report in detail the theoretical aspects for this localization. In this way, the computational cost of the nodal adjoint method decreases by several orders of magnitude. Our investigations show that this expansion is a significant enhancement compared to previous implementations and results in a rapid calculation of the Jacobian matrix with a high level of accuracy. The discrete dipole approximation and the newly efficient Jacobian matrices are effectively implemented to produce quantitative images of the simplified breast phantom from the microwave imaging system.
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| 7. |
- Hosseinzadegan, Samar, 1987, et al.
(författare)
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Fast Jacobian Matrix Formulation for Microwave Tomography Applications
- 2021
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Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021.
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Konferensbidrag (refereegranskat)abstract
- We have developed a new technique for computing the Jacobian matrix for microwave tomography systems which is orders of magnitude faster than conventional approaches. It exploits concepts from the nodal adjoint method and previous observations that rows of the matrix can be plotted over the imaging domain to produce sensitivity maps associated with specific transmit/receive antenna pairs. It also requires that the forward solutions and parameter reconstruction distributions be represented on the same grid or mesh. In this way, it computes full rows of the matrix simultaneously via a simple vector-vector multiplication of the forward solutions associated with sources broadcasting from both the designated transmit and receive antennas times a scalar constant. The time savings is substantial and is viable for both 2D and 3D applications.
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| 8. |
- Pishnamaz, Seyed Moein, 1995, et al.
(författare)
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Analysis of the 2D Guided Mode Propagation in a 3D Dielectric Rod Antenna
- 2023
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Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the analysis of 2-dimensional guided mode propagation in a finite 3-dimensional dielectric rod antenna. An approximated model based on the summation of the guided modes multiplied by the coefficients obtained by projecting the 3D fields on the 2D fields is derived and the accuracy of that is investigated. The factors playing role in the error of the approximation are studied and concluded that the main cause of error in the approximation is the reflection from the truncation at the end of the rod rather than the radiating field along the rod.
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| 9. |
- Pishnamaz, Seyed Moein, 1995, et al.
(författare)
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Reducing Waves on the Body Surface in Near-Field Medical Diagnostics by a Dielectric Rod Antenna
- 2023
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:10, s. 7958-7969
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Tidskriftsartikel (refereegranskat)abstract
- The multipath interference caused by the waves traveling on the body surface is a factor that limits the detection accuracy of microwave-based biomedical diagnostic systems. The waves traveling along these paths do not carry information of the area of interest, which is inside the body and are more sensitive to the changes in the space close to the antennas. In this paper for the first time, by placing a dielectric rod between the radiating element of the antenna and the body, the waves on the body surface are largely reduced while the antenna remains matched to the body. We design a Dielectric Rod Antenna (DRA) by deriving a 2-dimensional analytical solution of the wave propagation in a 2-layers cylindrical structure. The design is extended to 3D and further optimized using numerical simulations. It was shown that the addition of the dielectric rod enhances the field confinement by a factor of 2. The performance of the antenna, as verified by phantom measurements, shows that using the DRA increases the ratio of the transmission coefficient to power on the body surface to up to 24 dB and the antenna bandwidth is increased by 71% compared with the antenna without the dielectric rod.
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| 10. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Investigation of an ultra wideband noise sensor for health monitoring
- 2020
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 20:4
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Tidskriftsartikel (refereegranskat)abstract
- Quick on-scene assessment and early intervention is the key to reduce the mortality of stroke and trauma patients, and it is highly desirable to develop ambulance-based diagnostic and monitoring devices in order to provide additional support to the medical personnel. We developed a compact and low cost ultra wideband noise sensor for medical diagnostics and vital sign monitoring in pre-hospital settings. In this work, we demonstrated the functionality of the sensor for respiration and heartbeat monitoring. In the test, metronome was used to manipulate the breathing pattern and the heartbeat rate reference was obtained with a commercial electrocardiogram (ECG) device. With seventeen tests performed for respiration rate detection, sixteen of them were successfully detected. The results also show that it is possible to detect the heartbeat rate accurately with the developed sensor.
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