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PHYSICS AND MEDICINE
MEETING IN SAN DIEGO
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For more information please contact
Phillip Schewe, 301-209-3092, pschewe@aip.org,
Martha Heil, 301-209-3088, mheil@aip.org,
Ben Stein, 301-209-3091, bstein@aip.org,
or James Riordon, 301-209-3084, jriordon@aip.org,
at the American Institute of Physics
**FOR IMMEDIATE RELEASE**
College Park, MD, 14 July 2003 -- The American Association of
Physicists in Medicine (AAPM) will hold its 45th annual meeting
on August 10-14 at the San Diego Convention Center. Almost 1000
abstracts will be presented on a variety of subjects at the intersection
of physics and medicine. Many of these topics deal with the development
of state-of-the-art imaging and therapeutic devices, and the
methodologies that go along with them.
The AAPM meeting webpage (http://www.aapm.org/meetings/03AM/)
contains links to the full program. In early August, the site
will link to a Virtual Pressroom with additional information.
INTRODUCTION
Physics and medicine are close allies. Ever since the discovery
of X-rays and their potential for medical imaging, physicists
have been vital to the advancement of medicine. Fundamental
research in optics, acoustics, electromagnetism, and particle
and nuclear physics has led to an array of indispensable medical
tools. Magnetic resonance images (using microwaves), CAT scans
(using X-rays), PET scans (using gamma rays), ultrasound scans
(using sound waves) and various types of radiotherapy are among
the physics-based devices that help doctors diagnose and treat
ailments ranging from broken bones to cancer.
The AAPM includes more than 4800 members dedicated to advancing
medical technology. Medical physicists contribute to the effectiveness
of radiological imaging procedures by developing new imaging
procedures, improving existing techniques, and assuring radiation
safety of imaging procedures. Physicists working in medical imaging
inspect and model equipment to ensure that images are acquired
at the highest possible quality for effective diagnosis of possible
abnormalities. Medical physicists working in radiation therapy
commission and develop new therapeutic techniques; collaborate
with radiation oncologists to design improved treatment plans;
and calibrate and model therapeutic equipment to ensure that
every patient receives precisely the prescribed dose of radiation
at the correct location.
HIGHLIGHTS OF THE SCIENTIFIC PROGRAM
The following is a sampling of some of the intriguing talks that
medical physicists will present at the meeting.
CT SCREENING FOR BREAST CANCER
Screening for and treating breast cancer is a major concern in
medicine. Screening involves diagnostic tests applied to those
who are not known to have cancer, and breast cancer screening
is typically performed with mammography, a relatively quick
process in which two x-ray views of the breasts are recorded
on film. Only about three out of 1,000 mammograms locates breast
cancer. Patients suspected of having cancer based upon screening
mammography are usually then studied with other methodologies,
such as MRI or ultrasound, which provide different types of
images that can supplement the diagnosis. Now, John Boone at
the University of California, Davis, is building a CT (X-ray
computed tomography) machine specifically for breast cancer
screening purposes. Dr. Boone hopes that the more detailed
information provided by the breast CT scan will result in earlier
detection of breast cancer, which means saving lives. Boone
(john.boone@ucdmc.ucdavis.edu) expects that the X-ray dose
for his CT process should not exceed the dose used in routine
mammography. He expects the breast CT scanner to undergo phase-2
clinical trials sometime next year. To repeat: this device
would be for cancer screening, not for cancer therapy. (Paper
Tu-C24A-1, Tuesday, 10 AM)
TERRORISM AND THE MEDICAL PHYSICIST
With their unique knowledge of radiation, medical physicists
are playing an important role in preparing for the threat of
a terrorism-related radiological attack. A session titled "Terrorism
and the Medical Physicist" will feature three speakers
representing academia, the clinical community, and government.
The first speaker, John Poston of Texas A&M, College Station,
TX, chaired the National Council on Radiation Protection and
Measurements committee that wrote a report called "Management
of Terrorist Events Involving Radioactive Material." He
will focus on several findings of the report, such as the problem
of the "worried well" -- panicked members of the
general public. In such a radiological emergency, experts estimate
that the worried well may outnumber those truly needing medical
attention by as much as 1000 to one. The second speaker, Richard
Morin of the Mayo Clinic, served on the American College of
Radiology committee that wrote a primer titled "Disaster
Preparedness for Radiology Professionals: Response to Radiological
Terrorism," which, for example, urges hospitals to understand
how to set up an area for treating radiation-incident victims
in their emergency rooms. The final speaker, Orhan Suleiman
of the Food and Drug Administration, has been involved with
federal counter-terrorism initiatives. He will focus on medical
countermeasures for radiological hazards, including newly emerging
areas of research, National Institute of Health funding, and
novel strategies to get medical products rapidly developed
and approved for use by the FDA. (MO-E20A-1, Monday, 4:00;
for more information on the session contact Orhan Suleiman
at SuleimanO@cder.fda.gov)
DIGITAL 3-D MAMMOGRAMS
Digital 3-D images for diagnostic mammograms work better than
the traditional film images, reports Mari Lehtimaki (mari.lehtimaki@fi.instrumentarium.com)
and her colleagues in a study from the Instrumentarium Corporation
Imaging Division, in Tuusula, Finland and Helsinki University
Central Hospital Mammography Department, in Helsinki, Finland.
The researchers re-examined breast tissue of 60 patients showing
no external signs of cancer but whose traditional diagnostic
work-ups showed potential problem spots. Intrumentarium's Tuned
Aperture Computed Tomography device was used to image the suspect
breast tissue from seven angles, all rotated from a main reference
point, where digital spot imaging is also done. The images
are then combined to form a 3-D image. The ability to look
at various slices of tissue makes it possible for doctors to
spot tiny changes in breast tissue that might go undetected
in a film mammogram and to distinguish whether the suspect
tissue is benign or cancerous. The researchers also envision
that this technique could pinpoint more precisely where a biopsy
should be performed. The team of medical physicists plans to
run studies of this technology in the US, and to measure TACT's
performance against ultrasound's. (Paper TH-C24A-6, Thursday
11:15 AM)
BETTER PICTURES FOR TREATING BAD BLOOD VESSELS
Arteriovenous malformation (AVM) is a congenital disorder affecting
an estimated one in every 1,000 people. It involves a tangled
web of blood vessels, typically in the brain or spinal cord.
Abnormally high blood flow can occur in AVMs, causing seizures,
paralysis, and other problems. Improving prospects for successfully
treating AVMs, the researchers of the medical physics department
in San Bortolo Hospital, Vicenza, Italy, led by Dr. Paolo Francescon,
have adapted a new imaging technology, called 3-D rotational
angiography (3DRA), so that the data could be used to plan
AVM treatments with the Cyberknife, a novel device produced
by a Stanford, California company called Accuray. Firing X-rays
from numerous angles to reach a precisely defined 3D region
where an AVM resides, the Cyberknife destroys the AVM while
avoiding healthy tissue surrounding it. 3DRA provides a more
accurate, three-dimensional picture of the AVM than previously
possible. In the method, a patient is injected with a substance
(called contrast enhancement medium) into the affected area
to produce 3-D pictures of the AVM. These high-quality pictures
then allow Cyberknife to target the AVM more completely and
precisely than before. To date, the researchers have successfully
treated 20 patients by combining 3DRA with Cyberknife (Paper
MO-D20A-1, Monday, 1:30 PM; reporters seeking more information
should contact fisica@fisica-vicenza.it).
BARIUM SHIELD TO PROTECT THE FETUS DURING CT SCANS
Computed tomography (CT) on a pregnant woman's chest puts the
fetus at risk due to the adverse effects of radiation. However,
researchers from the University of Chicago propose that it
may be possible to protect the fetus if the mother ingests
barium sulfate before CT radiation exposure. Because the fetal
dose during chest scans is mainly due to internal scatter of
incident radiation, the barium compound acts as an internal
shield that absorbs errant radiation. A study that simulated
a CT scan of a pregnant woman showed that ingesting a 40 percent
solution of barium sulfate would decrease the fetal dose to
a negligible level, so that even high-quality CT imaging could
be performed with minimal risk. Chester Reft will present data
from the study and discuss the potential for barium sulfate
internal shields at 11:00 AM on Wednesday. (Paper WE-C23A-4)
MAKING X-RAY CANCER DETECTION SAFER
Millions of women are screened for breast cancer each year using
X-ray techniques, but the radiation dose needed for detailed
investigation of early stages of breast cancer is also a level
that can cause cancer to develop. A new X-ray detector, developed
by medical physicist Dr. Polad Shikhaliev at the Department
of Radiological Sciences, University of California, Irvine,
and his colleagues, lowers the radiation dose enough to prevent
the test from hastening the disease. The device turns microchannel
plate detectors on their sides in order to trap more photons
coming in, making the X-ray more efficient and using less radiation.
A microchannnel plate detector contains an array of tiny holes
that organize X-rays into a coherent image and includes fewer
shadows on its high-resolution images. (Paper TH-C24A-3; Thursday,
10:30 AM)
SIX-DEGREES-OF-FREEDOM POSITIONER
Correctly positioning a patient is an important part of radiotherapy
with externally incident radiation beams. Accuracy and flexibility
are important considerations. Currently, commercial positioners
are mostly attached to the ground and provide only one or two
rotations around a vertical axis and three mutually perpendicular
translational motions. The accuracy is about 1-2 millimeters.
Now, medical physicists at the Loma Linda University Medical
Center in California have developed a positioner with full
translational and rotational freedom under computer control.
The accuracy of positioning is 0.1 millimeters and past positioning
can be retrieved to hasten subsequent patient setup. According
to Michael Moyers (moyers@proton.llumc.edu , 909-558-0552),
the new patient positioner should cost only marginally more
than conventional positioners, cost much less than other high-precision
positioners, and should be able to reduce treatment time along
with better alignment of radiation treatment beams. (Paper
Tu-D20D-7, Tuesday, 1:30 PM)
WHITE-MATTER ATLAS OF THE BRAIN
The functions of the human body such as movement, thought and
vision involve different parts of the brain in the outer layer
called the cortex, where electrical signals are generated.
These signals travel across to the inner part of the brain,
known as the white matter, and onto other parts of the body.
The white matter consists of many pathways and can be thought
of as a complicated network of electrical cables, just like
those you might find in your home. A break in one of the cables
might result in the lights to one part of your house not working,
while the others continue to work normally. The brain works
in a similar way; damage to the white-matter pathway that connects
the motor cortex to the rest of the body will result in a loss
of movement, whereas damage to a different pathway will result
in a different problem. Until now it has been very difficult
to obtain pictures of these white-matter pathways. However,
a new magnetic resonance imaging technique called diffusion
tensor tractography allows medical physicists to obtain for
the first time images of these pathways by studying the way
in which water moves in the brain. The white-matter pathways
of the brain can be highlighted because water can move more
freely along them. Neuroscientists and neurologists are concerned
with how the brain works and how its functions are affected
by disease. By producing detailed pictures of the white matter
pathways in the brain we now have the opportunity to examine
more closely how damage to different parts of the white matter
can lead to a loss of function and disability. The development
of an atlas of the brain showing the white matter connections
in any individual will help neurologists to better understand
diseases such as multiple sclerosis, stroke, Alzheimer's disease
and other diseases of the brain. Chris Clark (cclark@sghms.ac.uk)
of St. George's Hospital Medical School in London will describe
progress toward a white-matter atlas on Wednesday at 2:00 PM
(Paper WE-D23A-3, Wednesday, 1:30 PM).
NATIONWIDE EVALUATION OF X-RAY TRENDS (NEXT)
Each year, the U.S. Food and Drug Administration conducts a study,
called NEXT, that explores trends in technology and clinical
methods, including X-ray doses administered to patients. Past
NEXT surveys have concentrated on the adult chest, abdomen,
upper gastrointestinal fluorosocopy, CT for the head, and dental
radiography. The 2002 NEXT survey was devoted to the abdomen
and lumbosacral spine, and preliminary results will be summarized
by Albert E. Moyal of the FDA (aem@cdrh.fda.gov). Compared
to the last abdomen/spine NEXT survey, conducted in 1995, the
2002 report will feature a reduction in exposure values, an
increase in film optical densities, and an improvement in film
processing. (Paper Tu-C25A-1, Tuesday, 10 AM)
COVERING THE MEETING
The AAPM meeting webpage (http://www.aapm.org/meetings/03AM/)
contains links to the full program and hotel information for
the meeting. With proper credentials, journalists covering
the meeting for specific publications can receive complimentary
registration to all the sessions and exhibits. While the meeting
will not have a newsroom, AIP and AAPM staff will be on hand
to facilitate any of your needs, including contacting researchers,
during the meeting.
In early August, the site will link to a Virtual Pressroom with
additional information on selected papers. In case you cannot
make it to San Diego for the meeting, the email contacts at the
top of this release can help you cover the conference from your
desk.
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REPORTER'S REPLY FORM
AAPM Meeting 2003
Please return this form to Phil Schewe at pschewe@aip.org or
by fax to 301-209-0846
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