Design and Performance Of A Thermal Neutron Beam for Boron Neutron Capture Therapy At The University Of Missouri Research Reactor J.D. Brockman J.C. McKibben
In situ activation reaction, 10 B(n, a) 7 Li; releases ionizing energy within volume of single cancer cell: Targets of traditional and current interest: High-grade Glioma Primary and Metastatic Melanoma Neutron 5 mm 10 mm 7Li(+3) (0.85 MeV) 10 B Gamma (0.48 MeV) Current FDA approved boron delivery agents: BSH: Sodium Borocaptate BPA: Boronophenylalanine GB-10: Na 2 B 10 H 10 Head and Neck Tumors Metastatic Liver Tumors a (+2) (1.49 MeV)
Thermal neutron beam Au cadmium ratio >100 Th flux ~1X10 9 n/cm 2 /s Minimize gamma dose Irradiation facility accessible during reactor operation Irradiate small animals up to large dogs
Key Design Feature: Single Crystal Silicon and Single Crystal Bismuth Neutron Filters Silicon Bismuth
Silicon and Bismuth Total Cross Sections (Amorphous) Si (Natural) 209Bi 1 ev 1 ev Source: OECD-NEA (Janis)
Thermal Cross Sections for Silicon and Bismuth Source: Kim et al. Phys. Med. Bio (2007) Lee, Byung-Chul, 2007 KAERI, Private communication. Freund (1983)
KAERI Data for S.C. Si and Bi ENDF/B Nuclear Data ENDF/B Nuclear Data MCNP5 Monte Carlo Angular Neutron Flux at Silicon Filter Entrance Neutron Flux at Irradiation location COMBINE 7.1 (W.Yoon, INL) 59-Group ENDF/B VII Custom Library DORT 2D S n S. R. Slattery, D. W. Nigg, J. D. Brockman, M. F. Hawthrone, PHYSOR, May 9 2010, Pittsburg, Pa
59 group Source from DORT calculation
1e+10 1e+9 1e+8 Flux/lethargy 1e+7 1e+6 1e+5 Empty Beam Tube 50 cm Silicon Crystal 50 cm Si + 8 cm Bi 1e+4 1e-9 1e-8 1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 Energy, MeV
1. Voided Beam 2. 50 cm Silicon crystal 3. 8 cm Bismuth Crystal 4. 50 cm Silicon + 8 cm Bismuth Crystal
Measured Thermal Flux (n/cm 2 -s) Calculated Thermal Flux DORT + MCNP5 (n/cm 2 -s) Cadmium Ratio Wire saturation activity ratio (Au/Cu) Voided Beamline 9.8 x 10 9 (11%) 9.4 x 10 9 (10%) 3.18 (7%) 8 cm Bi Crystal 3.4 x 10 9 (8%) 3.8 x 10 9 (10%) 5.10 (7%) 50 cm Si Crystal 2.6 x 10 9 (8%) 2.2 x 10 9 (10%) 65.3 (7%) 50 cm Si + 8 cm Bi 9.4 x 10 8 (8%) 9.6 x 10 8 (10%) 105.5 (7%) 36.4 28.4 22.4 22.4
Neutron Interaction 197 Au (n, γ) Bare Foil 55 Mn (n, γ) Bare Foil Thermal Thermal Energy Range of Primary Response 411 847 Activation Gamma Energy (kev) 115 In (n, γ) Cd Cover 1 ev Resonance 1293 2 6 Group spectrum 1 197 Au (n, γ) Cd Cover 5 ev Resonance 411 3 186 W (n, γ) Cd Cover 18 ev Resonance 686 4 55 Mn (n, γ) Cd Cover 340 ev Resonance 847 5 63 Cu (n, γ) Cd Cover 1 kev Resonance 511 (Positron) 5 115 In (n,n') Boron Sphere 300 kev Threshold 336 6
Flux/Lethargy 1.E+09 6 Group spectrum 2012 1.E+08 Bare Au, Mn 1.E+07 Cd W group 1 group 2 group 3 group 4 1.E+06 Cd In Cd Au Cd Cu, Mn B In group 5 group 6 A-Priori 1.E+05 1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 Energy, ev Nigg, et al, Med Phys. 27 359-367
Measured Φ th 2012 = 7.65 x 10 8 n/cm2-s (±8.6%) Measured Φ th 2009 = 8.85 x 10 8 n/cm2-s (±8.3%) Measured Φ th 2008 = 8.18 x 10 8 n/cm2-s (±6.0%) Calculated Φ = 9.6 x 10 8 n/cm2-s (±5%) Cadmium Ratio (Au) = 108 Calculated D γ = 2.12 cgy/min Measured D γ = 3.4 cgy/min (paired ion chamber technique)
1e+8 1e+9 n/cm 2 /s 1e+7 1e+6 Group 6 n/cm 2 /s 1e+5 2008 2009 2012 0 1 2 3 4 5 6 Energy Group 1e+8
Cu/Au wires Mean Au activity: 9.73X10 14 dps/n ± 4% Mean Au/Cu ratio: 22.1 ± 1.7%
Profile flux wire Profile flux wire Phantom A Phantom B Start of Shielding Center, index wire Phantom D Phantom C
Au Activity Relative to center wire 180 Start of Li Carbonate neutron shielding Edge of animal holder 160 140 120 100 80 60 Inside Shielding Phantom inside beam Center of Beam Phantom A Phantom B 40 20 0-4.0-3.0-2.0-1.0 0.0 1.0 2.0 Distance in cm from top edge of black cap
Cu activity, relative to center wire 250 200 150 100 50 Phantom D Front Back Li Shielding Start Cap Start 0 0 2 4 6 8 Length, cm
Tumor Flank downstream thorax in beam thorax down stream Thermal Flux, n/cm^2/s 1.3X10 9 1.9X10 8 1.3X10 8 7.1EX10 7 Thermal Flux Relative to tumor 100% 14% 10% 5% Thorax upstream 6 Li shield Tumor Thorax Down Stream Flank Downstream
Neutron spectrum has not changed since 2008 Radial profile measurements Phantom measurements and animal experiments are underway Acknowledgements Dr. David Nigg INL Dr. Frederick Hawthorne IINMM MURR Staff Operations Health Physics Machine Shop Electrical Shop
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