The goal of this work is to develop a technique to measure the x-ray diffraction signals of breast biopsy specimens. A biomedical x-ray diffraction technology capable of measuring such signals may prove to be of diagnostic use to the medical field. Energy dispersive x-ray diffraction measurements coupled with a semianalytical model were used to extract the differential linear scattering coefficients [mus(x)] of breast tissues on absolute scales. The coefficients describe the probabilities of scatter events occuring per unit length of tissue per unit solid angle of detection. They are a function of the momentum transfer argument, x=sin(theta/2)/X, where theta=scatter angle and lambda=incident wavelength. The technique was validated by using a 3 mm diameter 50 kV polychromatic x-ray beam incident on a 5 mm diameter 5 mm thick sample of water. Water was used because good x-ray diffraction data are available in the literature. The scatter profiles from 6 degrees to 15 degrees in increments of 1 degrees were measured with a 3 mm x 3 mm x 2 mm thick cadmium zinc telluride detector. A 2 mm diameter Pb aperture was placed on top of the detector. The target to detector distance was 29 cm and the duration of each measurement was 10 min. Ensemble averages of the results compare well with the gold standard data of A. H. Narten ["X-ray diffraction data on liquid water in the temperature range 4 degrees C-200 degrees C," ORNL Report No. 4578 (1970)]. An average 7.68% difference for which most of the discrepancies can be attributed to the background noise at low angles was obtained. The preliminary measurements of breast tissue are also encouraging.

A CdZnTe detector (CZTD) can be very useful for measuring diagnostic x-ray spectra. The semiconductor detector does, however, exhibit poor hole transport properties and fluorescence generation upon atomic de-excitations. This article describes an analytic model to characterize these two phenomena that occur when a CZTD is exposed to diagnostic x rays. The analytical detector response functions compare well with those obtained via Monte Carlo calculations. The response functions were applied to 50, 80, and 110 kV x-ray spectra. Two 50 kV spectra were measured; one with no filtration and the other with 1.35 mm Al filtration. The unfiltered spectrum was numerically filtered with 1.35 mm of Al in order to see whether the recovered spectrum resembled the filtered spectrum actually measured. A deviation curve was obtained by subtracting one curve from the other on an energy bin by bin basis. The deviation pattern fluctuated around the zero line when corrections were applied to both spectra. Significant deviations from zero towards the lower energies were observed when the uncorrected spectra were used. Beside visual observations, the exposure obtained using the numerically attenuated unfiltered beam was compared to the exposure calculated with the actual filtered beam. The percent differences were 0.8% when corrections were applied and 25% for no corrections. The model can be used to correct diagnostic x-ray spectra measured with a CdZnTe detector.

In our lab, a research program focused on identifying breast cancer by measuring the x‐ray scatter signals is under development. In an attempt to help us determine how the misalignment of the experimental setup and the fluorescence escaping affect our measured results in our particular experimental conditions, we have developed a set of simulation programs written in C++ object‐oriented language. We use a 5 mm diameter 5 mm thick water target as our sample and a cadmium zinc telluride detector. We have simulated the scattering in the sample, incorporated misalignments in our system and studied the effects of K‐fluorescence escape from our detector. We simulate monoenergetic beams with energies of 15 keV, 25 keV, and 35 keV. We also consider a 50 kV x‐ray spectrum. The angles studied range from 5° to 16° . The misalignments are that the beams on either the target or the detector are offset by (0.5mm, 0.5mm) or (−0.5mm, −0.5mm) from the center, or the detector angle has an offset of ±0.2 degrees. We find small percent differences ranging from −1.65% to 4.91% for aligned versus misaligned geometries. We anticipate that we can align our system to obtain good results. The K‐fluorescence escape probability varies as a function of the incoming photon energy and the depth of interaction in the detector. The highest escape probability of 11% occurs for a photon energy of about 33 keV. The escaping is essentially from the top surface of our detector and we may need to take this effect into account.

Our research group is focused on determining the potential applications of using x‐ray diffraction signals to diagnosis breast cancer. We have built a custom made x‐ray diffractometer system. Polyenergetic 50 kV beams collimated down to a 3 mm diameter are incident on 5 mm diameter 5 mm thick samples. A cadmium zinc telluride detector is positioned at an angle θ with respect to the center of the target. We use our semianalytic model coupled with energy dispersive x‐ray diffraction measurements to extract differential linear scattering coefficients in units of m−1 sr−1. We optimize our system with H2normalO as our target since good x‐ray diffraction data is available. A 2‐mm diameter aperture is positioned in front of our detector and the target to detector distance is ≈ 40 cm. We use a root‐mean‐square deviation to measure the overall agreement between our data and the gold standard. We get values of 1.6 and 2.0 m−1 sr−1 for scatter angles of 13° and 16° and values of 3.4, 2.5, 2.1, 2.8, 1.8 m−1 sr−1 for angles 5, 7, 8, 9, and 11. These values are obtained after correcting our data for fluorescence escape and hole tailing. However, the values are nearly the same even if we don't correct the data. At this stage, more optimization is required. Our preliminary results for breast tissue agree well with data measured by Kidane et al., Phys. Med. Biol. 44, 1791–1802 (1999). We intend to correlate the x‐ray diffraction and cellular pathology signals of breast tissue.