X-ray scattering for the characterization of lyophilized breast tissue samples

Target-filter combination effects on breast tissue characterization using mammographic X-rays: A Monte Carlo simulation study

BACKGROUND

Characterization of normal and malignant breast tissues using X-ray scattering techniques has shown promising results and applications.

OBJECTIVE

To examine possibility of characterizing normal and malignant breast tissues using the scattered photon distribution of polyenergetic beams of 30 kV X-rays.

METHODS

A Monte Carlo simulation is upgraded so that it is capable of simulating input mammographic X-ray spectra from different target-filter combinations, tracing photon transport, and producing the distribution of scattered photons. The target-filter combinations include Mo-Mo, Mo-Al, Mo-Rh, Rh-Rh, Rh-Al, W-Rh, and W-Al. Analysis of obtained scattered photon distribution is carried out by comparing the ratio of count under the peak in the momentum transfer region from 0 to 1.55 nm-1, to that in the region from 1.6 to 9.1 nm-1 (covering the regions of scattering from fat and soft tissue, respectively) for breast samples with different percentages of normal tissue (0-100%).

RESULTS

Mo-Mo target-filter combination shows a high linear dependence of the count under peak ratio on the percentage of normal tissue in breast samples (R2 = 0.9513). Despite slightly less linear than Mo-Mo, target-filter combinations other than Rh-Rh, W-Rh, and W-Al produce high linear responses (R2 > 0.9)CONCLUSION:Mo-Mo target-filter combination would probably be the most relevant in characterizing normal and malignant breast tissues from their scattered photon distribution.

Novel Zeff imaging method for deep internal areas using back-scattered X-rays

Elemental kinds, composition ratios, effective atomic number (Z_eff), and spatial distributions are the most basic information on materials and determine the physical and chemical properties of materials. X-ray fluorescence analysis have conventionally been used for elemental mapping, however maps on deep internal areas cannot be obtained because the escape depth of fluorescence X-rays is limited to a few mm from the surface of samples. Herein, we present a novel Z_eff imaging method that uses back-scattered X-rays. The intensity ratio of elastic and inelastic back-scattered X-rays depends on the atomic number (Z) of a single-element sample (Z_eff for a plural-element sample), and so Z_eff maps in deep areas can be obtained by spectrum analysis of the scattered high-energy incident X-rays. We demonstrated the feasibility of observing a phantom covered by an aluminum plate by using synchrotron radiation X-ray. A fine Z_eff map that can be used to identify materials was obtained from only front-side observation. The novel method opens up a new way for Z_eff mapping of deep areas of thick samples from front-side observation.

Plasma membrane proteins: A new probe for the characterization of breast cancer

This work aimed to characterize normal, benign and malignant excised breast tissues through the analysis of the FTIR spectra of their plasma membrane proteins. Tissue characterization parameters such as peak position, peak intensity, area under the peak, relative peak intensity and relative area under peak were evaluated mainly for protein spectral peaks; 1150 cm^-1, Amide I, Amide II, Amide III, and Amide A. The sensitivity, specificity and diagnostic accuracy for each parameter were obtained and Receiver Operating Characteristic (ROC) Curves were plotted. Results showed significant spectral differences between normal and benign tissues compared to malignant tissues at 1536 and 1645 cm^-1. The three tissues could be distinguished at 2900 cm^-1, where the malignant peak uniquely split into two separate peaks. ROC curves showed that the Amide A peak position yielded a higher accuracy compared to all other investigated characterization parameters. The deconvolution of Amide I revealed the conformational changes in plasma proteins characterizing the transformation to malignancy (a decrease in the percentage of alpha helix accompanied by an increase in the percentage of beta sheets). The use of the present structure-based analysis in conjunction with histopathological examination of excised breast tissues would offer an enhanced characterization that might reduce possible personal diagnostic mistakes.