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UID:20260523T173835EDT-9248rBHHj5@132.216.98.100
DTSTAMP:20260523T213835Z
DESCRIPTION: \n\nAbstract\n\nBreast cancer is one of the leading causes of 
 death among cancers in women. Early detection is widely considered as cruc
 ial for improving survival rates. The gold standard of mammography employs
  X-rays\, which not only pose health risks that limit frequency of exams\,
  but also face difficulties with dense tissues. Other clinical solutions\,
  such as magnetic resonance imaging\, have limited reach due to high costs
 . Microwave radar technology is a current research field for safe and effe
 ctive lower-cost alternatives for breast cancer screening\, relying on the
  dielectric contrast between healthy and tumour tissues.\n\nOur research g
 roup investigates the use of an array with 16 flexible antennas that can b
 e eventually implemented on a low-cost device for frequent scans at home\,
  which would flag any suspicious anomalies for further clinical exams. Thi
 s thesis focuses on design of and experiments with a narrowband system usi
 ng discrete frequencies in the 2.0 – 2.2 GHz range\, connected to the ante
 nna array in a 3D printed hemisphere developed previously for an ultrawide
 band system that sends continuous-time pulses between 2 – 4 GHz.\n\nNarrow
 band technology has the advantages of ample commercial availability and lo
 wer cost compared to ultrawideband\, while the latter is capable of better
  temporal and spatial resolution. Traditionally\, radar applications have 
 favoured higher bandwidths\, but widespread telecommunications in the micr
 owave range operate on narrowband. This continues to elicit debate within 
 the scientific community regarding what is more suitable for advanced appl
 ications\, such as biomedical imaging.\n\nExperimental signals with breast
  tissue phantoms\, initially obtained in the frequency domain (FD)\, were 
 analyzed to verify distinctions between tumour and baseline cases\, explor
 ing data repeatability over several measurement dates\, signal losses with
 in phantoms and the effect of noise levels\, including high-powered microw
 ave oven interference. Investigations on data variability are rare in this
  field\, generating important results for identifying measurement uncertai
 nty and reliability. Distinction between different phantom properties was 
 clear from signal distributions.\n\nChirp Z-Transform was applied successf
 ully to convert narrowband signals to the time domain (TD)\, leading to th
 e implementation of a clutter rejection procedure (removing undesirable re
 sponses) using normalization\, signal alignment and average trace subtract
 ion\, which resulted in significant improvement to signal-to-clutter ratio
 s on a per channel basis.\n\nComparisons were performed between narrowband
  and ultrawideband system measurements\, particularly in the TD\, includin
 g the use of the delay-multiply-and-sum beamforming algorithm for image ge
 neration. Results expectedly provided more limited resolution\, yet under 
 certain conditions the tumour response was highlighted successfully\, indi
 cating that narrowband signals contain sufficient information for tumour i
 dentification. Also noted was that the clutter rejection techniques applie
 d had different impacts for each system.\n\nAdditionally\, a second-genera
 tion discrete-frequencies prototype concept was introduced for future work
 \, using a software-defined radio transceiver\, which will add flexibility
  to prototype diverse pulse bandwidths\, capable of operating in either na
 rrowband or ultrawideband. Theoretical noise analyses indicate it also pro
 vides improvements to noise performance and\, thus\, amplitude resolution.
 \n\nOverall\, the results presented here highlight the potential of narrow
 band technology for breast cancer detection\, as well as the importance of
  properly processing and analyzing on the level of individual signals for 
 extraction of relevant information.\n
DTSTART:20221202T171500Z
DTEND:20221202T171500Z
LOCATION:\, Room 603\, McConnell Engineering Building\, CA\, QC\, Montreal\
 , H3A 0E9\, 3480 rue University
SUMMARY:PhD defence of Leonardo Gouvêa e Silva Fortaleza - Narrowband RF Sy
 stem with Flexible Antennas for Breast Cancer Detection
URL:/ece/channels/event/phd-defence-leonardo-gouvea-e-
 silva-fortaleza-narrowband-rf-system-flexible-antennas-breast-cancer-34388
 4
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