  The question of whether or not neutron therapy works has been answered. It is
a qualified yes, as is the case with all of radiation therapy. But, neutron
therapy has not kept pace with the rest of radiation therapy in terms of beam
delivery techniques. Modern photon and proton based external beam radiotherapy
routinely implements image-guidance, beam intensity-modulation and
3-dimensional treatment planning. The current iteration of fast neutron
radiotherapy does not. Addressing these deficiencies, however, is not a matter
of technology or understanding, but resources. The future of neutron therapy
lies in better understanding the interaction processes of radiation with living
tissue. A combination of radiobiology and computer simulations is required in
order to optimize the use of neutron therapy. The questions that need to be
answered are: Can we connect the macroscopic with the microscopic? What is the
optimum energy? What is the optimum energy spectrum? Can we map the sensitivity
of the various tissues of the human body and use that knowledge to our
advantage? And once we gain a better understanding of the above radiobiological
issues will we be able to capitalize on this understanding by precisely and
accurately delivering fast neutrons in a manner comparable to what is now
possible with photons and protons? This presentation will review the
accomplishments to date. It will then lay out the questions that need to be
answered for neutron therapy to truly be a 21st Century therapy.
