The presentation "Distributed X-ray Source Development" by K Frutschy et al. will be at 1:30 p.m. on Monday, July 19 in room 201B of the Philadelphia Convention Center.
This research was funded by the NIH.
10) TESTING PROTON CLUSTERS
The aim of most radiation therapy methods is to kill tumors while doing as little damage as possible to surrounding healthy tissue. Beams of protons are efficient in this regard, but there are several ways of delivering protons. The conventional way is to speed them up using the same kind of electronic devices used at particle accelerators. Another is to smash laser pulses into a target, where protons are liberated not singly but in bunches. Some scientists believe that effectiveness for delivering radiation to a tumor might be superior, at least in some situations, for laser-generated proton clusters.
Eugene Fourkal and his colleagues at the Fox Chase Cancer Center in Philadelphia are performing computer simulation studies (but no clinical trials, yet) with clusters -- varying the concentration and relative spacing of the protons within clusters -- in an effort to see what works best. One practical measure of success is determining the relative biological effectiveness, or RBE, the dimensionless number showing the effectiveness of the given particle beam in killing cancer cells relative to photons (with energy 1.25 MeV) for the same physical dose level in terms of "Grays" (or Gy, the ratio of energy absorbed to the mass).
"Laser-accelerated protons are coming in a cluster," says Fourkal, "and if their concentration is high enough (inter-proton distance is small enough) the interference effects the protons encounter in the tumor may lead to higher cluster stopping power as well as a
|Contact: Jason Socrates Bardi|
American Institute of Physics