Document Detail

Boron self-shielding effects on dose delivery of neutron capture therapy using epithermal beam and boronophenylalanine.
MedLine Citation:
PMID:  10587238     Owner:  NLM     Status:  MEDLINE    
Previous dosimetry studies for boron neutron capture therapy have often neglected the thermal neutron self-shielding effects caused by the 10B accumulation in the brain and the tumor. The neglect of thermal neutron flux depression, therefore, results in an overestimation of the actual dose delivery. The relevant errors are expected to be more pronounced when boronophenylalanine is used in conjunction with an epithermal neutron beam. In this paper, the boron self-shielding effects are calculated in terms of the thermal neutron flux depression across the brain and the dose delivered to the tumors. The degree of boron self-shielding is indicated by the difference between the thermal neutron fluxes calculated with and without considering a 10B concentration as part of the head phantom composition. The boron self-shielding effect is found to increase with increasing 10B concentrations and penetration depths from the skin. The calculated differences for 10B concentrations of 7.5-30 ppm are 2.3%-8.3% at 2.3 cm depth (depth of the maximum brain dose) and 4.6%-17% at 7.3 cm depth (the center of the brain). The additional self-shielding effects by the 10B concentration in a bulky tumor are investigated for a 3-cm-diam spherical tumor located either near the surface (3.3 cm depth) or at the center of the brain (7.3 cm depth) along the beam centerline. For 45 ppm of 10B in the tumor and 15 ppm of 10B in the brain, the dose delivered to the tumors is approximately 10% lower at 3.3 cm depth and 20% lower at the center of the brain, compared to the dose neglecting the boron self-shielding in transport calculations.
S J Ye
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medical physics     Volume:  26     ISSN:  0094-2405     ISO Abbreviation:  Med Phys     Publication Date:  1999 Nov 
Date Detail:
Created Date:  1999-12-17     Completed Date:  1999-12-17     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0425746     Medline TA:  Med Phys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2488-93     Citation Subset:  IM    
Department of Medical Physics, Rush University Medical Center, Chicago, Illinois 60612, USA.
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MeSH Terms
Boron Compounds / administration & dosage*
Boron Neutron Capture Therapy / methods*
Brain Neoplasms / radiotherapy
Models, Statistical
Monte Carlo Method
Phantoms, Imaging
Phenylalanine / administration & dosage,  analogs & derivatives*
Radiation Protection / methods*
Radiation-Sensitizing Agents / administration & dosage*
Radiotherapy Dosage / standards*
Reg. No./Substance:
0/Boron Compounds; 0/Radiation-Sensitizing Agents; 63-91-2/Phenylalanine; 76410-58-7/4-boronophenylalanine
Erratum In:
Med Phys 2000 Feb;27(2):424

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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