Dosimetry in Thermal Neutron Irradiation Facility at BMRR
- Brookhaven National Lab. (BNL), Upton, NY (United States)
Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4 - 7 % lower than the statistical mean derived from the Monte-Carlo modeling (5% uncertainty). The dose rate measured by ion chambers was 6 - 10 % lower than the output tallies (7% uncertainty). The detailed dosimetry that was performed at the TNIF for the NCT will be described.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States), National Nuclear Data Center
- Sponsoring Organization:
- USDOE Office of Science (SC)
- OSTI ID:
- 1183272
- Report Number(s):
- BNL--107705-2014-IR; KB0301041
- Country of Publication:
- United States
- Language:
- English
Similar Records
Epithermal beam development at the BMRR (Brookhaven Medical Research Reactor): Dosimetric evaluation
An Optimized Epithermal Neutron Beam for Neutron Capture Therapy (NCT) at the Brookhaven Medical Research Reactor (BMRR)
Technical aspects of boron neutron capture therapy at the BNL Medical Research Reactor
Conference
·
Thu Aug 24 00:00:00 EDT 1989
·
OSTI ID:5473833
An Optimized Epithermal Neutron Beam for Neutron Capture Therapy (NCT) at the Brookhaven Medical Research Reactor (BMRR)
Conference
·
Sun May 31 00:00:00 EDT 1992
· Progress in Neutron Capture Therapy for Cancer
·
OSTI ID:6007950
Technical aspects of boron neutron capture therapy at the BNL Medical Research Reactor
Conference
·
Tue Jul 01 00:00:00 EDT 1997
·
OSTI ID:495766