Designing accelerator-based epithermal neutron beams for boron neutron capture therapy.
The 7Li(p,n)7Be reaction has been investigated as an accelerator-driven neutron source for proton energies between 2.1 and 2.6 MeV. Epithermal neutron beams shaped by three moderator materials, Al/AlF3, 7LiF, and D2O, have been analyzed and their usefulness for boron neutron capture therapy (BNCT) treatments evaluated. Radiation transport through the moderator assembly has been simulated with the Monte Carlo N-particle code (MCNP). Fluence and dose distributions in a head phantom were calculated using BNCT treatment planning software. Depth-dose distributions and treatment times were studied as a function of proton beam energy and moderator thickness. It was found that an accelerator-based neutron source with Al/AlF3 or 7LiF as moderator material can produce depth-dose distributions superior to those calculated for a previously published neutron beam design for the Brookhaven Medical Research Reactor, achieving up to approximately 50% higher doses near the midline of the brain. For a single beam treatment, a proton beam current of 20 mA, and a 7LiF moderator, the treatment time was estimated to be about 40 min. The tumor dose deposited at a depth of 8 cm was calculated to be about 21 Gy-Eq.
E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. DLBleuel@lbl.gov
D L
DL
Bleuel
R J
RJ
Donahue
B A
BA
Ludewigt
J
J
Vujic
D000535:Aluminum; D055592:Biophysical Phenomena; D001703:Biophysics; D016754:Boron Neutron Capture Therapy / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005214:Fast Neutrons / Q000627:therapeutic use*; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy; D012542:Scattering, Radiation; D013679:Technology, Radiologic; D014057:Tomography, X-Ray Computed
D000535:Aluminum