Anyone whos ever had a mammogram knows the
understatement in the words You may feel a little discomfort. Anyone whos
had a false positive result from a mammogram knows the panic that quickly
displaces the discomfort. But most women also know that adding mammograms
to clinical exams is the best detection system there is for breast cancera
life-threatening disease diagnosed in 192,000 American women each year.
What most people dont know is that todays mammograms miss
15 to 20% of breast tumors.
There may soon be an alternative to conventional mammograms, providing
much sharper, more detailed imaging, thanks to a team of researchers
by NC State professor of physics Dr. Dale Sayers. The new approach would
require significantly less compression of the breast during imaging,
womens biggest deterrent to regular screening.
The new process, called Diffraction Enhanced Imaging (DEI), shows 8 to
14 times more contrast than conventional radiographs (see figure). It
uses a single-energy fan beam of x-rays instead of the broad-energy beam
of conventional radiography. An analyzer crystal is placed in the x-ray
beam between the film and the object being studied, diffracting a particular
wavelength of x-ray through the physics principle known as Braggs
law. The resulting image shows changes in x-ray refraction as the beam
passes through the target, and highlights the edges of tissue structures.
Sayers started working on the project eight years ago with Drs. William
Thomlinson and Zhong Zhong (scientists at the Brookhaven National Synchrotron
Light Source), Dr. Dean Chapman (formerly at Brookhaven and now at Illinois
Institute of Technology), and Dr. Etta Pisano (Chief of Breast Imaging
at the UNC School of Medicine). At UNC, Pisano and NC State alum Dr. Chris
Parham are clinically validating the technology for breast imaging, comparing
conventional digital x-ray images of biopsy tissue samples with DEI images
of the same samples, and designing future in vivo studies.
Thomlinson, Zhong, and Chapman invented the concept using the $100 million
Brookhaven synchrotron light source, but a portable version must be developed
for clinical use if DEI is
to replace conventional mammograms. Assisted by students, Sayers and NC
State nuclear engineers Kuruvilla Verghese and Mohamed Bourham are using
computer models to understand the science of DEI, develop a clinical prototype,
and work on other possible applications. Sayers contends that if the prototype
works, it would work for many applications, especially in contrasting
lung tumors from foam-like lung tissue.
Its not often that an atomic physicist gets to apply results
directly to patients, says Sayers. But if DEI can be applied
at the clinical level, it has the potential of replacing mammograms as
a clinical tool, finding tumors earlier, reducing false positives and
negatives, and saving many lives.
Sayers recently received the International X-ray Society (IXS) Outstanding
Achievement Award for his career achievements in developing the field
of XAFS (X-ray Absorption Fine Source), a major imaging tool used around
the world for the past 20 years. The XAFS technology and process, which
led to Sayers work with DEI, helps to better understand atomic
level structure of complicated materials.