Berkeley Lab Radiobiology Researchers Transfer Decades of Know-How to New Brookhaven Facility
February 24, 1996
By Jeffery Kahn, JBKahn@LBL.gov
Although other facilities took up some of the slack when funding ended
for the Bevalac, its loss was a severe blow to charged particle
radiation research. Now, thanks in no small part to the efforts of
Engineering and Life Sciences division staff, much of what was
accomplished in turning the Bevalac into one of the world's first and
finest facilities for heavy ion radiation biology has been "recycled"
into a new facility at Brookhaven National Laboratory.
Life Sciences Division researchers, sponsored by DOE and NASA among
others, will be major users of the Brookhaven facility. Berkeley Lab,
in collaboration with Colorado State University, is a NASA Specialized
Center of Research and Training (NSCORT) in radiation biology, with a
mandate to train some of the next generation of radiation
scientists.
According to Life Sciences physicist Jack Miller, in addition to its
value as basic science, research in this field has particular
importance to two groups of people -- cancer patients and astronauts.
Says Miller, "We have a lot to learn about the biological effects of
densely ionizing radiation such as cosmic ray heavy ions. The
knowledge we gain will not only help protect astronauts but will also
improve our understanding of both the basic biology and the therapeutic
uses of these particles."
Brookhaven's Alternating Gradient Synchrotron (AGS), a dedicated
particle and nuclear physics facility, had never before been used for
radiobiology, and to do so presented significant technical challenges,
similar in many respects to those encountered over many years of
development at the Bevalac.
Miller says creating the new Brookhaven research facility -- in a
sense, resurrecting the Bevalac radiobiology facility -- was a
two-year-long labor of love for Bevalac veterans such as Engineering's
R. P. Singh and Mark Nyman and Life Sciences' Bernhard Ludewigt, some
of whom worked nights and weekends on their own time, transferring
knowledge and hardware to Brookhaven.
Computer and electronic systems and monitoring devices for dosimetry
that evolved and were refined over decades at the Bevalac were located,
refurbished or rebuilt as necessary, and moved to Brookhaven. These
systems monitor the radiation dose delivered to experimental targets as
well as the uniformity and composition of the particle beam, and
are critical to the success of accelerator-based biology experiments.
Singh was responsible for the software, while Nyman accounted for much
of the electronics engineering. Ludewigt, as he had at the Bevalac,
acted as the liaison between biologists and accelerator specialists.
Miller and Life Sciences physicists Lawrence Heilbronn, Cary Zeitlin
and Ken Frankel were responsible for installing and running the
dosimetry system at the AGS, and Life Sciences biologists Amy
Kronenberg and Priscilla Cooper helped design the facility for staging
biological samples at the accelerator.
The Bevalac was both a pioneering facility in the treatment of cancer
with heavy ions, and one of a very few accelerators in the world -- and
at the time of its shutdown, the only one in the U.S. --which routinely
accelerated heavy ions to the energies most commonly observed in space.
Up until now, astronauts have not traveled much beyond the Earth. Due
to the protection provided by the Earth's magnetic field, the radiation
environment near the Earth is dramatically different than that
encountered in interplanetary space. Heavy ions are of relatively
little concern near the Earth, but may turn out to be a major hazard on
interplanetary missions. For instance, it has been estimated that
during a three-year mission to Mars, up to one third of an astronaut's
cell nuclei would be traversed by a heavy ion. The very long lead
times for mission planning dictate that research into the consequences
of such traversals be conducted now, in anticipation of a return to the
Moon and voyages to Mars during the first decades of the next century.
Heavy ions can also be harnessed to attack cancerous tissue. Charged
particle radiotherapy -- the targeting of a beam of charged particles
on a tumor -- was pioneered at this Laboratory and at the Harvard
cyclotron, and has now spread to facilities in more than ten
countries. Like x-rays, charged particles are able to pass through
tissue. However, whereas x-rays begin to give up their energy
immediately when they first encounter tissue, charged particles deposit
almost all of their energy or radiation dose where they stop. This
stopping point can be precisely manipulated to coincide with the
location of a tumor through the use of a beam delivery system developed
here.
Miller says that the effort to transfer know-how and hardware to
Brookhaven really made him appreciate the breadth of resources
available here. "In addition to engineers and scientists," he said, "we
needed computer technicians, electronics specialists, riggers,
carpenters and the shipping department, some times on pretty short
notice, and everyone came through."
He also praised the staff at Brookhaven for its efforts. "Just as
pushing an accelerator to its upper energy limit is a challenge, so is
running it at its lower limit. The AGS is optimized for high energy
nuclear physics. For radiobiology, the beam had to be dialed down to
about 1 GeV/nucleon, well below its comfort zone. You can think of
this in terms of getting an internal combustion engine to idle at 20
r.p.m. rather than at 700. The accelerator people called this `running
in the mud', but they made it work very well."
The first AGS radiobiology run took place this past October, with beams
of iron ions. (Iron was chosen because it is the heaviest ion present
in significant numbers in cosmic rays.) Forty-one scientists from 12
institutions took part in the highly successful run. Life Sciences
Division principal investigators participating included Kronenberg
(mutagenesis in human and rodent cells); Cooper and Bjorn Rydberg (DNA
damage and repair in human and rodent cells); Mary Helen Barcellos-Hoff
(epithelial cell transformation); and Miller (heavy ion fragmentation
related to astronaut exposures and shielding).
Decades of study on the biological effects of high-energy heavy charged
particles all but came to a halt in the U.S. three years ago. That's
when this Laboratory, which invented nuclear medicine half a century
ago, shut down its Bevalac accelerator.