Milica Popovic’s research while affiliated with McGill University and other places

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Publications (102)


AI-Enhanced SDR Microwave Breast Cancer Screening Transceiver: A Comparative Study
  • Article

January 2025

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4 Reads

IEEE Transactions on Microwave Theory and Techniques

Milad Mokhtari

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Leonardo Fortaleza

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Le Chang

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Milica Popović

Microwave transceivers play a crucial role in microwave breast screening systems, significantly influencing the final product performance, cost, and form factor. This article presents a portable and economically viable yet high-performing microwave transceiver designed based on the software-defined radio (SDR) architecture. This transceiver is intended to complement a switching matrix and antenna array, forming a novel microwave breast cancer screening prototype. This new system aims to replace two older transceivers, which are included in this study for comparative analysis. The comparison is conducted on a purposely designed test bench against a commercially available vector network analyzer (VNA) used as the benchmark. In addition, this VNA serves as a reference for training a denoising autoencoder neural network, aimed at enhancing the signal integrity of the new prototype. Comparative evaluations are performed across the time domain, frequency domain, and delay-multiply-and-sum (DMAS) image domain. The findings reveal that the SDR-based prototype achieves satisfactory and comparable imaging results, all while costing a fraction of the price of alternative systems.



Models of Melanoma Growth for Assessment of Microwave-Based Diagnostic Tools

September 2024

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9 Reads

IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology

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Rachel Tchinov

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Oliver Miller

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[...]

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Milica Popović

Malignant melanoma, the aggressive form of skin cancer, progresses via radial and vertical growth. The aim of this study is to assess the feasibility of microwave-based diagnosis of melanoma at different stages of tumor progression. To this end, we used the physiological data for melanoma progression to develop a theoretical model of melanoma growth, followed by the oil-in-gelatin based tissue phantoms, which aim to mimic the dielectric behavior of the tissues under consideration. The phantoms are then dielectrically characterized using a slim-form open-ended coaxial probe by systematically sampling dielectric values across the mimicked skin surfaces at a range of points over the 0.5 – 26.5 GHz frequency range. The resulting observations revealed that the microwave spectroscopy exhibits the capability not only to distinguish between healthy and malignant skin, but also differentiate between tumors at different stages of vertical growth, which may not be visually discernible from the skin surface. The measured results are compared with the estimated dielectric values of malignant melanoma using Lichteneker's mixing equation obtained from the literature and it was observed that the measured results closely agree with the literature values.


Surface Wave and Back Radiation Suppression in Microwave Breast Screening

September 2024

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3 Reads

IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology

The challenges in antenna design for microwave-based breast screening systems identify two distinct needs: 1) to minimize the surface-wave propagation at the interface between the substrate and the tissue, and 2) to address the back-radiation. These surface waves become more noticeable within the substrate, particularly when a confining ground plane is present, and yet the ground plane is pivotal for achieving unidirectionality and shielding against environmental radiation. This paper introduces a simplified human breast model and offers a quantitative analysis of existing surface waves. We then propose a 16-antenna array of cavity-backed patch antennas with parasitic elements, designed for operation in the 3.1–5.1 GHz range. Each antenna element is optimized to function seamlessly alongside the breast tissue. Full-wave simulations illustrate that the proposed antenna array achieves superior unidirectionality and diminished mutual coupling levels when compared to its predecessor. We further outline the cost-effective fabrication method that employs the SYLGARD(TM) 184 silicone elastomer PDMS kit. The measurements from the fabricated antenna elements are consistent with the results of the full-wave simulations.





UWB Microwave Breast Screening With Self- Mixed Baseband Analog Signal Processing

April 2024

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28 Reads

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2 Citations

IEEE Sensors Journal

This paper proposes an affordable and fast microwave imaging prototype using a time-domain baseband imaging technique with ultrawideband (UWB) impulse signals. Unlike traditional methods that sample the signal at RF, the signal of the proposed device is self-mixed to be downconverted to baseband, and then sampled using a real-time oscilloscope with a sub-GHz bandwidth. This noticeably simplifies the receiver and speeds up the signal acquisition. The required RF section of the receiver, including the low-noise amplifier (LNA) and self-mixer, is fabricated using a 65 nm CMOS integrated-circuit (IC) technology. Due to the low-frequency content of the received signals, traditional confocal imaging techniques cannot be directly used, and hence an energy-based imaging technique is also proposed. Experiments using a 3-D phantom with a skin layer show 0.5-1.8 cm localization accuracy in the detection of a 1 cm diameter tumor.



Size-Adaptive Occipital 18-Channel Receive-Only RF Coil for 3T MRI

January 2024

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1 Read

IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology

The performance of a conformal occipital receive-only radio-frequency (RF) array is demonstrated at 3T. The ultimate aim of this larger coil is to improve whole-brain magnetic resonance imaging (MRI) regardless of a person's head size and shape. The occipital array contains 18-channels built on a 3D-printed 3-mm thick thermoplastic polyurethane (TPU) plate, which acts as a flexible substrate. To show the performance improvements of our design a comparative study was performed where three differently shaped phantoms were used when imaging by our occipital array then by a standard rigid 64-channel head product coil (posterior 40-channel section only). Signal-to-noise-ratio (SNR) and noise correlation performance were evaluated. Compared to the product coil, the flexible occipital array improved mean SNR by 2.8×. Noise correlation was comparable to the product coil. These results lead us to conclude that our design represents a viable approach to improve SNR for differently shaped heads and supports the feasibility of a larger 128-channel size-adaptable whole-head array currently in development.


Citations (69)


... The basic idea behind microwave imaging is to use microwaves to illuminate an item of interest, and then by detecting dispersed field values outside the object, reconstruct the form or distribution of the dielectric constant [3,4]. Microwave imaging used in detecting breast tumors can obtain highresolution, highly accurate images because it has the advantages of large bandwidth, short wavelength, and excellent directionality [5]. ...

Reference:

Ultra-wideband Imaging of Breast Tumors Based on Global Back Projection Algorithm
UWB Microwave Breast Screening With Self- Mixed Baseband Analog Signal Processing
  • Citing Article
  • April 2024

IEEE Sensors Journal

... Complex models that faithfully replicate the detailed anatomy are usually resource-intensive, requiring substantial computational power for numerical simulations and, in the subsequent stage, complicated and costly fabrication process for controlled, phantombased experiments. Building on our initial findings in [17], this work focuses on managing the complexity of tissue models to balance accuracy and efficiency. Specifically, the finger anatomy was selected as the sample subject for several reasons. ...

Finger Models: Example of Complex Geometry in Investigations on Microwave Skin Cancer Diagnosis
  • Citing Conference Paper
  • September 2023

... In recent years, many microwave and millimeter-wave (mm-wave) imaging technologies have emerged to cater to a multitude of applications based on the principles of synthetic aperture radar (SAR). These innovative applications span various domains such as nondestructive testing and evaluation (NDT&E) [1][2][3][4][5][6][7], security inspection [8][9][10][11][12][13], and medical imaging [14][15][16][17][18][19][20]. Revolutionizing aerial surveillance, small unmanned aerial vehicles (UAVs) emerge as pivotal players in SAR imaging [21][22][23][24][25][26]. ...

Integrated Fast UWB Time-Domain Microwave Breast Screening
  • Citing Article
  • January 2023

IEEE Transactions on Instrumentation and Measurement

... explores two lager tumor sizes (d = 4 mm, t = 1 mm; d = 6 mm, t = 1.5 mm), along with the small one (d = 2 mm, t = 0.5 mm), where tumor size, together with tumor type and frequency, is analyzed as factors that determine model complexity selection and identify essential tissue layers. The tumor dimensions in Section 3.2.3 are selected to reflect the tendency of the tumors to progress in both horizontal and vertical directions [23,24]. ...

Microwave Spectroscopy of Melanoma Progression Model
  • Citing Conference Paper
  • March 2023

... Their simulations proved that tumorous tissues have different SAR values than healthy tissues. The use of arrays improve the performance of the system by eliminating the need to changing the position of the antenna on the breast in case it is used alone not in an array system, [10]. In [11] a system of two antennas placed diametrically opposite with the breast in between is proposed. ...

PDMS Unidirectional Antenna Array for Microwave Breast Screening
  • Citing Conference Paper
  • September 2022

... 50 The phantoms of human head tissues are prepared using different chemical compositions and experimentally validated for the detection of brain stroke. 51 Different types of skin tissues and tumors are mimicked in Ref. 52 for the monitoring of skin diseases using various chemical compositions. In this research, the human blood samples are mimicked to attain close resemblances to the dielectric properties of real human blood, where other properties of blood are not our current area of interest. ...

Heterogeneous Skin Phantoms for Experimental Validation of Microwave-Based Diagnostic Tools
  • Citing Article
  • Full-text available
  • March 2022

Sensors

... Differences in εr between normal and cancerous tissues are instrumental in diagnosis, as tumor tissues typically display higher water content (>60%) due to increased hydration from rapid cancer cell metabolism. The dielectric constant, εrʹ plays a crucial role in distinguishing between normal (εrʹ < 50 at 2.45 GHz) and cancerous (εrʹ > 50 at 2.45 GHz) tissue, offering a diagnostic indicator for cancer detection based on εr values [7,8,9,10,11,12,13,14]. Consequently, the sensitivity of the SPR-sensor system to water content, influenced by tumor metabolism, contributes significantly to tumor detection. ...

Skin Phantoms for Microwave Breast Cancer Detection: A Comparative Study
  • Citing Article
  • May 2021

IEEE Journal of Electromagnetics RF and Microwaves in Medicine and Biology

... The studies that were selected for possible inclusion based on their abstract and title (n = 468) were then evaluated with respect to the inclusion and exclusion criteria. One hundred seventy-five papers were identified for inclusion in this review [11][12][13][14][24][25][26][27][28][29][30][31][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][68][69][70][71][181][182][183][184][185][186][187][188][189][190][191][192][195][196][197][198][199][200][201]. Nine additional papers [17,32,50,67,72,180,193,194,202] that were not in the Scopus search results but which nonetheless fit the inclusion criteria were also selected for inclusion in this review. ...

Microwave Radar for Breast Health Monitoring: System Performance Protocol
  • Citing Conference Paper
  • December 2020

... Microstrip antennas are attracting the attention of researchers working in the field of breast cancer detection systems [20] such as wearable systems [21], [22], thanks to their many advantages such as compact size, light weight, ease of fabrication, simple design and low cost [23]. Even if ultra-wide band is said to be an important requirement with high importance for cancer detection systems [24], narrow band systems resulting from such antennas provides comparable performance in that same area according to [25]. It has a much lower cost than UWB systems, which makes it easily accessible in low-income countries having economic challenges [17]. ...

Flexible 16-Antenna System for Microwave Breast Screening: NB vs. UWB Performance
  • Citing Conference Paper
  • July 2020