Early, painless, inexpensive cancer detection
raditional X-ray mammography creates a breast image by passing
high-energy ionizing radiation through a highly compressed breast to
film on the other side. Though this process has warned thousands of
cancer, it is far from perfect, notes Assistant Professor Susan Hagness (center).
Hagness is working with Associate Professor of Radiology Frederick
Kelcz (right) to develop a low-cost, computer-based microwave
tumor-detection system that could improve early detection and
eliminate the trauma of unnecessary biopsies. The planned microwave
sensor will include a small flat panel containing an array of
miniature antennas placed gently on the surface of the breast. The
devices are inexpensive enough to make them widely accessible in
health care. In addition, microwave imaging carries no danger of
ionizing radiation exposure.
Microwaves interact with human tissues primarily according to water
content. Because malignant tumors have a much higher water content and
more vascularization than normal breast tissue, microwaves can provide
the basis for a highly sensitive detection system. In Hagness's
research, low-power microwave pulses are used to interrogate the
tissue. Cancerous lesions back-scatter the pulses, producing a
microwave echo. The measurements of those echoes enable Hagness to
develop a 3-D image of malignant tumors.
Graduate student Kristen Leininger (left), Hagness and Kelcz collect
data on breast tissue removed through hundreds of excisional biopsies
at UW Hospitals and Clinics. The information will be used to develop a
microwave sensor capable of detecting very small lesions and
discriminating between malignant and benign cases.
HSX plasma device moves into experimental phase
After eight years, more than 100,000 hours of effort, $7.5 million,
and an incredibly complex design and fabrication process, the
14-member team of the Helically Symmetric Experiment (HSX) created the
first plasma in the program's new stellarator. Associate Professor
David Anderson and co-investigators Simon Anderson and Joseph Talmadge
are now measuring the device's attained magnetic field structure
through electron beam mapping techniques.
A stellarator is a "magnetic bottle." Fusion plasma research has the
goal of making a miniature star by heating heavy isotopes of hydrogen
to ignition. Plasmas are achieved by heating matter to intensely high
temperatures, creating a glowing, gas-like state that can conduct
electricity. Magnetic fields constrain the high-temperature plasma. In
the presence of magnetic fields, charged particles orbit around the
magnetic lines. With the proper orientation of the magnetic lines of
force, a "bottle" is formed and the particles can be prevented from
touching material walls and losing energy.
HSX combines the best attributes of tokamaks and
stellarators. Tokamaks require a strong current in the plasma
itself. Stellarators don't need that current, but generally don't
produce the high-quality magnetic field required to confine plasmas at
higher temperatures. HSX solves that problem by achieving symmetry in
the magnetic field through its oddly-shaped magnet coils.
780,000 tiny mirrors shed new light on DNA
The gene chip, which permits scientists to analyze thousands of genes
at once, may soon come within easy reach of researchers. Writing in
the October issue of the journal Nature Biotechnology, UW-Madison
scientists described a new way to inexpensively and simply manufacture
the customized chips capable of deconstructing long segments of
DNA. The technique enables scientists to study human, animal and plant
"The recently announced mapping of the human genome opens incredible
possibilities for this type of chip," says Professor Franco Cerrina . "It's an ideal tool for making use of the genetic map in
discovering gene variations."
The interdisciplinary team includes ECE's Cerrina; visiting scientist
Yongjian Yue; Roland Green, environmental toxicology program, now at
NimbleGen Systems; physicist Sangeet Singh-Gasson, now at Motorola;
Clark Nelson, Biotechnology Center; Professor Fred Blattner, genetics;
and Professor Michael Sussman, horticulture and genetics.
The Wisconsin team capitalizes on display projection technology
involving 780,000 micro-mirrors arranged on a computer chip,
eliminating the need for the complex mask process used in previous
high-density DNA chip technology. In addition, the technology reduces
fabrication time to only a few hours.