City Research Online

Abstract

This project utilised two radiation scatter interactions in order to characterise breast tissue. These two interactions were Compton scatter, used to measure the electron density of the tissues, and coherent scatter, with the analysis of coherent scatter diffraction patterns. Measurements of these parameters were made both in a laboratory and at a synchrotron source. The tissue samples investigated comprise of five different tissue classifications: adipose, malignancy, fibroadenoma, normal fibrous tissue and fibrocystic change (FCC).

This first part of this study describes a technique for measuring the electron density of breast tissue using Compton scattered photons. In the laboratory, the KU2 line from a tungsten target industrial x-ray tube (57.97 keV) was used and the scattered x-rays collected at an angle of 30°. At this angle the Compton and coherent photon peaks can be resolved using an energy dispersive detector and a peak fitting software program. Measurements made at the European Synchrotron Radiation Facility were performed at 13keV with the detector at 112°. The system was calibrated using solutions of known electron density. The results obtained have shown that there is a difference between adipose and malignant tissue, to a value of 7.3%, and between adipose and FCC, to a value of 10.7%. These figures are found to be significant by statistical analysis. The differences between adipose and fibroadenoma tissues (0.5%) and between malignancy and FCC (3.2%) are not significant.

The second part of this study measures the coherent scatter profiles of each tissue type, using an energy dispersive method in the laboratory and an angular dispersive method at two synchrotrons. A novel normalisation technique was developed, which uses the electron density values for each sample that were measured during the first part of this study. The results of these measurements were analysed using a method of fitting peaks to the scatter profiles. The peaks obtained for each tissue type were compared using a Kruskal-Wallis analysis of variance test. Adipose and FCC tissues were easily differentiated from the other tissues. No substantial differences were found between the normal fibrous, malignant and fibroadenoma tissues, which are all fibrous tissue types.

Finally a technique of multivariate analysis was used to combine the scatter profile spectra and the electron density values into a tissue classification model. The number of parameters used in the model was refined, by grading the success of each subsequent model. The best model that was formulated was able to classify seven out of ten test samples correctly. This technique was efficient at detecting differences in the coherent scatter spectra that were not evident when the individual peaks were compared separately.

A description of the new measurement system that has been installed at City University in order to continue this work has been included, with reference to how this study aided the final experimental design.

Publication Type:	Thesis (Doctoral)
Subjects:	R Medicine > RZ Other systems of medicine
Departments:	School of Health & Psychological Sciences > Midwifery & Radiography School of Health & Psychological Sciences > School of Health & Psychological Sciences Doctoral Theses Doctoral Theses

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