16 research outputs found
A preliminary study for early breast cancer detection with microwaves
Breast cancer is the most common type of cancer in female all over the world. Early detection and treatment gives a chance to overcome this cancer. In breast cancer detection, there are many methods such as X-ray mammography, Magnetic Resonance Imaging, and Ultrasound Imaging. However, existing these methods have limitations such as X-rays, disturbing pressure on the breast, and high cost of devices, etc. Because of all the reasons mentioned, microwave breast imaging has the potential to overcome from some of the limitations of conventional breast cancer screening systems. The physical basis breast cancer detection by microwaves depends on the difference between the dielectric properties of normal and malignant breast tissue. Microwave breast cancer imaging is also a noninvasive method and it has low cost. Therefore, microwave imaging technology for breast cancer detection has attracted much attention by many researchers in these days. By using Computer Simulation Technology Microwave Studio and Antenna Magus Software, breast model with tumor and antennas were generated in this study. The presence of the tumor was investigated using a receiver and a transmitting antenna. While the transmitting antenna was stationary, the receiving antenna was moved to different positions. S11 (return loss) results were evaluated. This study is a preliminary study to determine the location and characteristic features of the tumor. Furthermore, this study will show that scanning methods will determine the location and size of the tumor at higher accuracy and the reconstruction of the reflected waves will allow to clearly determining the location of the tumor
Evaluation of limestone layer’s effect for uwb microwave imaging of breast models using neural network
X-ray mammography is widely used for detection of breast cancer. Besides its popularity, this method did not have the potential of discriminating a tumor covered with limestone from a pure limestone mass. This might cause misdetection of some tumors covered with limestone or unnecessary surgery for a pure limestone mass. In this study, Ultra-Wide Band (UWB) signals are used for the imaging. A feed-forward artificial neural network (FF-ANN) is used to classify the mass in the breast whether it is a tumor or not by using the transmission coefficients obtained from UWB signals. A spherical tumor covered with limestone and pure limestone masses were designed and placed into the fibro-glandular layer of breast model using CST Microwave Studio Software. The radius of the masses for both cases is changed from 1 mm to 10 mm with 1 mm steps. Horn antennas were chosen to send and receive Ultra-Wide Band (UWB) signals between 2 and 18 GHz frequency range. The obtained results show that the proposed method, on the contrary of the mammogram, has the potential of discriminating the tumor covered with limestone from the pure limestone, for the mass sizes of 7, 8 and 10 mm. Consequently, the UWB microwave imaging can be used to distinguish these cases from each other
Okvirno rješenje za difrakciju ravnog vala impedacijskom trakom: slučaj H-polarizacije
In this study, the diffraction of H-polarized plane wave by an infinitely long strip which has the same impedance on both faces with a width of 2a is investigated by using an analytical-numerical method. The diffracted field is obtained by an integral equation in terms of the electric and magnetic currents induced by the incident field. This integral equation is reduced to two uncoupled integral equations that include only induced electric and magnetic currents separately. Both of the currents are defined as a sum of infinite series of Gegenbauer polynomials with unknown coefficients satisfying the edge conditions. The integral equations are transformed to linear algebraic equations by using analytical methods and the unknown coefficients are determined by solving numerically obtained matrix equations. Numerical examples on the RCS (radar cross section) are presented, and the far field scattering characteristics of the strip are discussed in detail. Some of the obtained results are compared with the other existing method.U ovom radu istražuje se difrakcija H-polariziranog ravnog vala od beskonačno duge trake koja ima jednak otpor na obje strane i širinu 2a korištenjem analitičkog-numeričke metode. Difraktirano polje dobiveno je putem integralne jednadžbe u smislu električnih i magnetskih struja induciranih upadnim poljem. Ova integralna jednadžba svedena je na dvije odvojene integralne jednadžbe koje zasebno uključuju samo inducirane električne i magnetske struje. Obje struje definirane su kao zbroj beskonačnog niza Gegenbauerovih polinoma s nepoznatim koeficijentima koji zadovoljavaju rubne uvjete. Integralne jednadžbe pretvorene su u linearne algebarske jednadžbe pomoću analitičkih metoda i nepoznati su koeficijenti utvrđeni rješavanjem numerički dobivenih matričnih jednadžbi. Predstavljeni su numerički primjeri na PRP-u (površina radarskog presjeka), a karakteristike rasipanja na dalekom polju kod traka detaljno su raspravljeni. Neki od dobivenih rezultata uspoređeni su s drugom postojećom metodom
The effects of dielectric values, breast and tumor size on the detection of breast tumor
Although breast cancer is the second main cause of female deaths after lung cancer, early diagnosis plays a crucial role to diminish the death rate. Many techniques have been improved to detect the cancerous cells. At different microwave frequencies, the malignant cells indicate different electrical characteristics as compared to the normal cells. According to these frequencies, the breast tissue is more permeable than other tissues such as the brain and muscle. Due to this property of the breast tissue, microwaves can be used for the detection of breast cancer. In this study, the breast prototype was modelled using the CST STUDIO SUITE electromagnetic simulation software with respect to different breast size, tumor size and dielectric values tested at a range of the 0-3.0 GHz frequency. The objective of this paper is to investigate the effects of each factor and the interactions of factors on detecting cancer cells using the factorial analysis. The results indicate that the factors such as fat and skin permittivity, tumor and breast sizes are more effective in the detection of breast tumor. Although the effect of fibro permittivity is not significant alone, there are considerable interaction effects of a large breast size and small tumor size through low-to-high values of fibro permittivity. Furthermore, the combinations of a breast radius smaller than almost 8.5 cm with a high level tumor radius and breast radius larger than 8.5 cm with a low level tumor radius are desirable for lessening the return loss value
Reference Breast Phantoms for Low-Cost Microwave Imaging
Microwave imaging provides an alternative method for breast cancer screening and the diagnosis of cerebrovascular accidents. Before a surgical operation, the performance of microwave imaging systems should be evaluated on anatomically detailed anthropomorphic phantoms. This paper puts forward the advances in the development of breast phantoms based on 3D printing structures filled with liquid solutions that mimic biological tissues in terms of complex permittivity in a wide microwave frequency band. In this paper; four different experimental scenarios were created, and measurements were performed, and although there are many vector network analyzers on the market, the miniVNA used in this study has been shown to have potential in many biomedical applications such as portable computer-based breast cancer detection studies. We especially investigated the reproducibility of a particular mixture and the ability of some mixes to mimic various breast tissues. Afterwards, the images similar to the experimentally created scenarios were obtained by implementing the inverse radon transform to the obtained data
Ocjena preciznog dielektičnog modela i izabranih patenta o otkrivanju raka dojke pomoću mikrovalova
Advances in microwave breast cancer detection and imaging during last decade are reported in this review paper. An introduction to breast cancer and detection methods and detailed information about microwave imaging and selected patents are presented. The advantages and disadvantages of the presented patents and also state of breast cancer detection and imaging are discussed. Microwave imaging for breast tumor detection is considered to be promising, as it is believed that there is a significant or detectable contrast in malignant, benign and normal tissues over a broad frequency range. Also, there have been many dielectric models, especially the double Debye model has been used to define the dielectric response of different biological tissues. On the other hand, double Debye model is not accurate for human breast tissue because there are knowledge limitations about the structure, dynamics, and macroscopic behavior of breast tissue. It is vital that, according to frequency, accurate dielectric model should be chosen in detection systems.Ovaj rad govori o naprecima u otkrivanju i snimanju raka dojke pomoću mikrovalova u posljednjem desetljeću. Dan je uvod o raku dojke i metodama otkrivanja te detaljne informacije o snimanju pomoću mikrovalova i izabranim patentima. Raspravljene su prednosti i nedostaci prezentiranih patenata kao i trenutno stanje u detektiranju i snimanju raka dojke. Snimanje mikrovalovima kako bi se otkrio rak dojke metoda je od koje se mnogo očekuje, pošto se smatra kako postoje znatni ili primjetni kontrasti između malignih, benignih i normalnih tkiva kroz široki raspon frekvencija. Također, postoje mnogi dielektrični modeli, posebno se dvostruki Debye model koristio u definiranju dielektričnog odziva raznih bioloških tkiva. S druge strane, dvostruki Debye model nije precizan prilikom korištenja za ljudska tkiva, jer postoje ograničenja u saznanjima oko strukture, dinamike i makroskopskog ponašanja tkiva dojke. Neophodno je, ovisno o frekvenciji, izabrati ispravan dielektrični model u sustavima za detekciju
Analysis of the Scattering Fields by Dielectric Sphere inside Different Dielectric Mediums: The Case of the Source and Observation Point is Reciprocal
Kanonik yapılardan elektromanyetik saçılma, elektromanyetik teoride önemli bir konudur. Bu
çalışmada, dielektrik geçirgenliği frekansa bağlı olan bir dielektrik küreden elektromanyetik saçılma
problemi, gelen dalganın eğik gelmesi durumu için çözülmüştür. Bu çalışmada küre, bir tümörün
elektromanyetik modeli olarak düşünüldüğü için frekansa bağlılık Cole‐Cole model ile gösterilmiştir.
Cole‐Cole model, biyolojik dokuların elektromanyetik olarak modellenmesi literatürde sıkça kullanılan
bir modeldir. Gelen dalga H‐polarize olarak düzlem dalga olarak varsayılmıştır. Küre yüzeyinden saçılan
alan ve küre içerisine iletilen alan ifadeleri Helmholtz denkleminden faydalanılarak bilinmeyen
katsayılı fonksiyonlar şeklinde yazılmıştır. Daha sonra, bu bilinmeyen katsayılar sınır koşulları
aracılığıyla belirlenmiştir. Elde edilen saçılan ve iletilen alan ifadesi, bistatik hal için nümerik olarak
incelenmiştir. Elde edilen saçılan alanın ifadesinin doğrulanması için kürenin elektromanyetik
özellikleri dielektrik küreye indirgenmiş ve saçılan alanın ifadeleri Harrington’un kitabındaki sonuçlar
ile karşılaştırılmıştır. Sonuçlar, alıcı ve verici kaynaklarının karşılıklı dönmesiyle daha hızlı ve daha iyi
elde edilmiştir. Ultra‐geniş bant radar‐tabanlı görüntüleme yaklaşımı, kötü huylu meme tümörleri gibi
önemli saçılım engellerinin sadece varlığını ve yerini belirlemesine odaklanan daha basit hesaplamalı
bir problemi daha hızlı çözebilmektedir. Bundan dolayı, bu yöntem biyomedikal mühendisliğinde
alternatif tarama ve teşhis aracı olarak kullanılabilir.The electromagnetic scattering from canonical structure is an important issue in electromagnetic
theory. In this study, the electromagnetic scattering from dielectric sphere with oblique incidence is
investigated. While an incident wave comes with a certain angle, observation point turns from 0 to 360
degrees. The electromagnetic field is considered as a plane wave with H polarized. The scattered and
transmitted field expressions with unknown coefficients are written. The unknown coefficients are
obtained by using exact boundary conditions. Then, the sphere is considered as having frequency
dependent dielectric permittivity. The frequency dependence is shown by Cole‐Cole model. The analytic
results are compared with scattered field by dielectric sphere obtained by Harrington. The results are
obtained faster and more reliable with reciprocal rotation. Ultra‐wide band (UWB) radar‐based imaging
approach can solve a simpler computational problem faster dealing with only to identify the presence
and location of significant scattering obstacles such malignant breast tumours. Therefore, it can be used
in biomedical engineering as an alternative screening and diagnosis tool
TÜRKIYE’DE YOĞUN BAKIM ÜNITELERINDE VENTILATÖR ILIŞKILI PNÖMONIYI ÖNLEMEK IÇIN ALINAN GÜNCEL ÖNLEMLER: TÜRK TORAKS DERNEĞI SOLUNUM YETMEZLIĞI VE YOĞUN BAKIM ÇALIŞMA GRUBU NOKTA PREVALANS ÇALIŞMASI
Objectives: The inadequate quality and nature of sleep is a commonly reported problem among hospitalized patients. The purpose of this study is to examine the effects of progressive muscle relaxation training program on sleep quality, sleep state, pain and life quality of patients who underwent pulmonary resection