Comparison of measured parameters from a 24--keV and a broad spectrum epithermal neutron beam for neutron capture therapy: An identification of consequential parameters

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Medical Physics; (USA)

DOI:https://doi.org/10.1118/1.596455· OSTI ID:5984205

Fairchild, R G; Saraf, S K; Kalef-Ezra, J; Laster, B H ^[1]

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1. Medical Department, Brookhaven National Laboratory, Upton, NY (USA)

Epithermal neutron beams are under development in a number of locations in the U.S. and abroad. The increased penetration in tissue provided by these neutrons should circumvent problems associated with the rapid attenuation of thermal neutron beams encountered in previous clinical trials of neutron capture therapy (NCT). Physical and radiobiological experiments with two intermediate energy'' or epithermal'' beams have been reported. A comparison is made here between the 24-keV iron-filtered beam at Harwell, England, and the broad-spectrum Al{sub 2} O{sub 3} moderated beam at the Brookhaven Medical Research Reactor (BMRR). In addition, parameters which are relevant for NCT, and which are best suited for evaluation and comparison of beams, are discussed. Particular attention is paid to the mean neutron energy which can be tolerated without significant reduction of therapeutic gain (TG), where TG is the ratio of tumor dose to maximum normal tissue dose. It is suggested that the simplest and most meaningful parameters for comparison of beam intensity and purity are the epithermal neutron fluence rate, and the fast neutron dose per epithermal neutron (4.2{times}10{sup {minus}11} rad/neutron for the broad-spectrum beam and 29{times}10{sup {minus}11} rad/neutron for the 24-keV beam). While the Al{sub 2} O{sub 3} beam is close to optimal, the 24-keV beam produces a significant fast neutron dose which results in a lower TG. It is argued that if sufficient intensity is available, TG is the parameter which determines the potential usefulness of a beam for NCT. Data are presented to illustrate that with an epithermal fluence rate of {approximately}1.8{times}10{sup 9} {ital n}/cm{sup 2} s, the Al{sub 2} O{sub 3} filtered beam at the BMRR is optimized and suitable for clinical application.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5984205
• Journal Information: Medical Physics; (USA), Journal Name: Medical Physics; (USA) Vol. 17:6; ISSN MPHYA; ISSN 0094-2405
• Country of Publication: United States
• Language: English

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ALUMINIUM OXIDES
BARYONS
BEAMS
BORON 10
BORON ISOTOPES
CHALCOGENIDES
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY TRANSFER
EPITHERMAL NEUTRONS
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ISOTOPES
KEV RANGE
KEV RANGE 10-100
LET
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NEUTRON BEAMS
NEUTRON CAPTURE THERAPY
NEUTRON FLUENCE
NEUTRON FLUX
NEUTRON THERAPY
NEUTRONS
NUCLEAR MEDICINE
NUCLEI
NUCLEON BEAMS
NUCLEONS
ODD-ODD NUCLEI
OPTIMIZATION
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
RADIATION FLUX
RADIOACTIVATION
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RADIOTHERAPY
STABLE ISOTOPES
THERAPY