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Accelerator‐based neutron brachytherapy
Author(s) -
Song Haijun,
Yanch Jacquelyn C.,
Klinkowstein Robert E.
Publication year - 2002
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1427308
Subject(s) - brachytherapy , neutron , neutron source , collimated light , materials science , linear particle accelerator , neutron temperature , dosimetry , beam (structure) , nuclear engineering , nuclear medicine , physics , nuclear physics , optics , radiation therapy , medicine , radiology , laser , engineering
The development and evaluation of a new approach to neutron brachytherapy is described. This approach, accelerator‐based fast neutron brachytherapy, involves the interstitial or intracavity insertion of a narrow, evacuated accelerator beam tube such that its tip, containing the neutron‐producing target, is placed in or near the tumor. Tumor irradiation via brachytherapy should result in a reduction in the healthy tissue complication rate observed when poorly collimated and/or low energy external neutron beam are used for treatment. Use of a variable energy accelerator provides an advantage over isotope sources for neutron brachytherapy in that the neutron beam can be turned on and off and the neutron energy spectrum varied for different treatment applications. A prototype accelerator‐based fast neutron brachytherapy device, 10 cm long and 6 mm outer diameter, has been constructed and evaluated in terms of its dosimetric output, treatment time, and practical feasibility. The prototype device is a tube‐in‐tube design with cooling water running between the inner and outer tubes to cool a beryllium target located at the tip of the inner tube. Cooling experiments were performed and coupled with Monte Carlo simulations to determine treatment times as a function of heat load for various neutron‐producing reactions. Using the9 Be ( d , n ) 10 B reaction at E d= 1.5 MeV, 66 RBE‐Gy (12 Gy physical dose) can be delivered to the boundary of a 4.5‐cm‐diam treatment volume in 8 min at a heat load of 130 W. Other reactions offer similar treatment times at somewhat higher bombarding energies and also show higher potential for dose enhancement with the boron‐10 neutron capture reaction due to their softer neutron spectra. Dose distributions in a water phantom were measured with the prototype brachytherapy tube using the dual‐ion chamber technique for the9 Be ( d , n ) 10 B reaction at E d= 1.5 MeV. The measurements and simulations agree within uncertainties and demonstrate that fast neutrons contribute more than 90% of the dose to the target volume.