Dr. Robert Leclair

Office: F-509
Lab: F-439A

Mailing Address:
Dr. R. Leclair
Department of Physics and Astronomy
Laurentian University
Sudbury, ON
P3E 2C6

Telephone:
Voice: (705) 675-1151, ext 4355, 2192
FAX: (705) 675-4868

Internet:
rleclair@laurentian.ca

Detection of the x-ray diffraction signals of breast tissue could provide a new means to diagnosis breast cancer.

Although breast tissues do not have long range-order like crystals, they do exhibit short-range order. A few studies have shown differences between the low-angle x-ray scatter signatures of healthy and malignant breast tissues. It is the differences in the molecular and intermolecular structures of breast tissues that are responsible for the distinct scatter signals. In our work we intend to systematically investigate the potential of using the low-angle x-ray scatter in the field of breast cancer diagnosis. We have built a custom made x-ray diffractometer for tissue characterization measurements. The system consists of a Faxitron X-Ray Corporation Model 43855C x-ray cabinet system configured to house an ionization chamber, a system of collimators, a tissue sample holder, a cadmium zinc telluride detector (CZTD) and positioning devices. In this work we are extracting the differential scattering cross section Us [per m per sr] by using our semianalytic x-ray diffraction model in conjunction with energy dispersive x-ray diffraction measurements. We validated our technique by using water as our sample since good x-ray diffraction data exists in the literature. Measurements with breast tissue specimens are currently under way. We also intend to duplicate our measurements at a synchrotron facility. The high flux of photons of the synchrotron beam will reduce measurement times and allow us to look at ultra low angles of scattered x rays. One of our goals will be to determine whether we can identify suspicious lesions within breast specimens by detecting scattered x rays. To help us with this task we have in our x-ray lab a state-of-the-art digital specimen radiography system.

Selected publications:

R.J. Leclair and P.C. Johns, "Optimum momentum transfer arguments for x-ray forward scatter imaging", Med. Phys., 29, 2881-2890 (2002)

R.J. Leclair and P.C. Johns, "X-ray forward-scatter imaging: Experimental validation of model", Med. Phys., 28, 210-219 (2001)

V.K.B. Kota, D. Majumdar, R. Haq, and R.J. Leclair, "Shell Model Tests of the Bimodal Partial State Densities in a 2x2 Partitioned Embedded Random Matrix Ensemble," Canadian Journal of Physics 77, 893-901 (1999)

R.J. Leclair and P.C. Johns, "Analysis of spectral blur effects in x-ray scatter imaging", Med. Phys., 26, 1811-1816 (1999)

R.J. Leclair and P.C. Johns, "A semianalytic model to investigate the potential applications of x-ray scatter imaging", Med. Phys., 25, 1008-1020 (1998)