No description available.

Background: Axillary lymph node dissection as routine part of breast cancer treatment has been questioned in relation to the balance between benefits and morbidity. The purpose of this study is to determine the association of tumor size, age and histological grade with axillary lymph node metastasis, to determine if some patients could be exempted from axillary dissection. Methods: The data are derived from BreastScreen NSW, the government sponsored population-based breast screening program. In New South Wales (NSW) Australia between 1995 and 2002, 7,221 patients with invasive breast carcinoma were diagnosed and 5,290 patients were eligible for this study. The relationship between incidence of positive axillary lymph nodes and three study factors (tumor size, age and histological grade) was investigated by univariate and multivariate analysis. Logistic regression models were used to predict probability of axillary metastases. Results: The incidence of axillary lymph node metastases was 28.6% (95% CI: 27.4%- 29.8%). Univariate analysis showed that age, tumor size and histological grade were significant predictors of axillary lymph node metastases (p<0.0001). Multivariate analysis identified age, tumor size and histological grade remained as independent predictors (p<0.0001). From multivariate analysis, patients with T1a (Less than or equal to 5mm) and grade I tumors regardless of age had 5.2% (95% CI: 1.2%- 9.3%) frequency of node metastases. Patients 70 years or older with grade I, T1a and T1b (6-10mm) tumors had 4.9% (95% CI: 3.2%- 7.5%) and 6.6% (95% CI: 5.3%-8.3%) predicted frequency of node metastases. Conclusions: Tumor size, age and histological grade are predictors of axillary lymph node metastases. Routine axillary lymph node dissection could be avoided in some patient groups with a low frequency of involved lymph nodes if the benefits are considered to exceed the risks.

Background: Axillary lymph node dissection as routine part of breast cancer treatment has been questioned in relation to the balance between benefits and morbidity. The purpose of this study is to determine the association of tumor size, age and histological grade with axillary lymph node metastasis, to determine if some patients could be exempted from axillary dissection. Methods: The data are derived from BreastScreen NSW, the government sponsored population-based breast screening program. In New South Wales (NSW) Australia between 1995 and 2002, 7,221 patients with invasive breast carcinoma were diagnosed and 5,290 patients were eligible for this study. The relationship between incidence of positive axillary lymph nodes and three study factors (tumor size, age and histological grade) was investigated by univariate and multivariate analysis. Logistic regression models were used to predict probability of axillary metastases. Results: The incidence of axillary lymph node metastases was 28.6% (95% CI: 27.4%- 29.8%). Univariate analysis showed that age, tumor size and histological grade were significant predictors of axillary lymph node metastases (p<0.0001). Multivariate analysis identified age, tumor size and histological grade remained as independent predictors (p<0.0001). From multivariate analysis, patients with T1a (Less than or equal to 5mm) and grade I tumors regardless of age had 5.2% (95% CI: 1.2%- 9.3%) frequency of node metastases. Patients 70 years or older with grade I, T1a and T1b (6-10mm) tumors had 4.9% (95% CI: 3.2%- 7.5%) and 6.6% (95% CI: 5.3%-8.3%) predicted frequency of node metastases. Conclusions: Tumor size, age and histological grade are predictors of axillary lymph node metastases. Routine axillary lymph node dissection could be avoided in some patient groups with a low frequency of involved lymph nodes if the benefits are considered to exceed the risks.

No description available.

A resistively loaded bowtie antenna, intended for applications in breast cancer detection, is adaptively modified through modelling and genetic optimization. The required wideband operating characteristic is achieved through manipulation of the resistive loading of the antenna structure, the number of wires, and their angular separation within the equivalent wire assembly. The results show an acceptable impedance bandwidth of 100.75%, with a challenge VSWR <; 2, over the interval from 3.3 GHz to 10.0 GHz. Feasibility studies were made on the antenna sensitivity for operation in a tissue-equivalent dielectric medium. The simulated and measured results are all in close agreement.

Attenuation and damping in elastography are naturally of great interest as the presence of these effects in biological tissue goes without question and therefore must be addressed if quantitative assessment of tissue elastic properties is to be achieved. Additionally, given the change in the tissue structure present in the diseases that elastographic imaging seeks to detect and diagnose, there is every reason to expect that the resulting lesions will also exhibit a change in their attenuation behaviour, indicating diagnostic value to any description of the damping property distribution elastographic methods are able to provide. This thesis will present the unique contribution of the development of several Elastographic models for MR based reconstructions of soft tissue. A method for the reconstruction of both Viscoelastic and Rayleigh damping based damped elastic properties has been developed for use with MR detected time-harmonic motion data and has been shown to lead to reasonable results in both homogeneous and heterogeneous phantoms of varying material types. A poro-elastic modelling is thought to provide a more accurate description of tissue structure by accounting for, in part, the complex interactions between the solid and fluid phases present in vivo. The foundation for a poro-elastic material behaviour will be explored and presented to support the premise. A meaningful mapping of the orthotropic shear moduli distributions in three directions has demonstrated enough evidence that the orthotropic MRE can be a feasible technique to determine orthotropic elasticity parameters of a biological tissue, noninvasively. The orthotropic achievements throughout this project can be useful for future clinical cancer diagnostics by augmenting the information obtained from the orthotropic MRE reconstructions between normal tissue and tumours.

The first project focused on the preparation, characterization, and application of dual emission quantum dot encoded mesoporous silica microparticles. The quantum dots were added in precisely controlled ratios and were stably encapsulated within the pores of the silica. Several experiments were performed to test the superior stability of the quantum dot-silica composites over dye-loaded silica particles. The composite particles exhibited very high fluorescence, were functionalized with antibodies, and were used as signal transducers for the detection of a protein expressed by breast cancer cells. The second project focused in more detail on the detection capabilities of the quantum dot-silica composites. Three different types of quantum dot-silica composites were prepared. Each type was loaded with a separate type of quantum dot with distinct emission wavelengths and was functionalized with separate antibodies for detection of three different breast cancer biomarkers. These three composite sensors were used together for the simultaneous detection of each of the breast cancer markers. The initial strategy utilized the direct detection method in which the antigen is nonspecifically adsorbed to a glass plate. An improved second strategy was more sensitive and used a capture antibody which was covalently bound to a glass plate to immobilize the antigen. The third project focused on the preparation and application of magnetic, fluorescent human serum albumin nanoparticle composites. A fluorescent drug analogue and iron oxide nanoparticles were encapsulated into 100 nm human serum albumin nanoparticles. The advantage of these composite particles is that they could be used as a theranostic tool which could target, detect, and treat diseased tissue in a single application. Release of the drug analogue from the nanocomposites was achieved by addition of proteolytic enzymes that are expressed or overexpressed in cancer cells. The temporal release of the fluorescent drug analogue was measured as a function of enzyme concentration. The amount of drug released was directly proportional to enzyme concentration.

A microwave imaging system processes scattered electromagnetic fields in the microwave region to create images. It is an alternative or complementary imaging tool that can be used in breast cancer imaging. It employs non-ionising radiation and during measurement, compression of the scanned body part is avoided. These benefits potentially lead to safer and more comfortable examinations. It also has the potential to be both sensitive and specific to detect small tumors, whilst being much lower cost than current methods, such as magnetic resonant imaging, mammography and ultrasound. This thesis reports a multi-layer active antenna array for breast imaging using microwaves from 3 GHz to 8 GHz. The proposed structure resolves the outstanding problem in the design of large active antenna arrays for tissue imaging, namely, the isolation of the antennas from the electronic circuits. A ground plane within the multi-layer design separates the antenna array from the electronics array while providing shielding to the antennas from the back and improved power coupling into the tissue. The possibility of a high-speed vertical connector to provide interconnection between the antenna array and the mixer array is investigated and measurements show that it could be utilized for the frequency range from 3 GHz to 8 GHz. / Thesis / Master of Applied Science (MASc)

We characterized the thermoacoustic and photoacoustic properties of large-area, few-layer graphene by pulsed microwave and optical excitations. Due to its high electric conductivity and low heat capacity per unit area, graphene lends itself to excellent microwave and optical energy absorption and acoustic signal emanation due to the thermoacoustic effect. When exposed to pulsed microwave or optical radiation, distinct thermoacoustic and photoacoustic signals generated by the few-layer graphene are obtained due to microwave and laser absorption of the graphene, respectively. Clear thermoacoustic and photoacoustic images of large-area graphene sample are achieved. A numerical model is developed and the simulated results are in good accordance with the measured ones. This characterization work may find applications in ultrasound generator and detectors for microwave and optical radiation. It may also become an alternative characterization approach for graphene and other types of two-dimensional materials. (C) 2016 AIP Publishing LLC.

Breast microwave imaging (BMI) is a novel modality that complements current breast screening tools. Microwave radar imaging creates a radar cross-section (reflection) map of the breast. The difference in permittivity between healthy and malignant tissue is between 10-50%. This contrast is significantly higher than that obtained with x-rays and supports the use of microwave imaging for breast cancer diagnosis. Prior to widespread clinical use, some areas require further study. Firstly, the performance of three different antennas was carried out, to assess their suitability for a BMI system. Secondly, the sampling constraint of a circular scan geometry was studied and tested using experimental phantoms and these antennas. For accurate breast BMI reconstruction, the transmission speed of the radio waves inside the breast must be determined. The tissue composition of each patient is different, making this task challenging. This work presents an algorithm for wave speed estimation in different mediums. / February 2017