Beam Profiles of an Epithermal Neutron Beam
The thermal neutron fluence profiles, the gamma-ray dose profiles and the fast neutron dose profiles have been measured free in-air as well as in phantoms irradiated with the clinical epithermal neutron beam for boron neutron capture therapy at the High Flux Reactor in Petten, The Netherlands. For this purpose a set of well characterized detectors has been used: a PN diode detector, a magnesium ionization chamber flushed with argon and a tissue-equivalent ionization chamber flushed with tissue-equivalent gas. The influence of collimator size on the various dose profiles has been determined in cubical water phantoms of different size for 8 cm, 12 cm and 15 cm diameter circular beam collimators. A minor influence of the phantom size on the various beam profiles was observed for the 8-cm and 12-cm field. For the 15-cm field, a profound influence of the phantom size was observed on the thermal neutron fluence profiles. A minor influence on the gamma-ray dose profiles was seen for this field size. A treatment planning system is under development to use the results of these measurements to calculate in a semi-empirical way, the various dose components at all clinically relevant points in patients irradiated with the epithermal neutron beam.
KeywordsThermal Neutron Field Size Beam Profile Boron Neutron Capture Therapy Dose Profile
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- 1.R.L. Moss, Current overview on the approach of clinical trials at Petten, in: “Boron Neutron Capture Therapy; Toward Clinical Trials of Glioma Treatment,” D. Gabel, R. Moss, ed., Plenum Press, New York, 1992, pp. 33–46.Google Scholar
- 3.R.D. Rogus, O.K. Harling and Y.0 Yanch, Mixed field dosimetry of epithermal neutron beams for boron neutron capture therapy at the MITR-Il research reactor, Med. Phys. 21: 161 1–1625, 1994.Google Scholar
- 5.S. Pospisil, E. Havrankova, Z. Janout, J. Konicek, I. Mach and J. Pavlu, Si diode as a small detector of slow neutrons, Radial. Prot. Dosim. 46: 115–118, 1993.Google Scholar
- 6.C.P.J. Raaijmakers, M.W. Konijnenberg and B.J. Mijnheer, Clinical dosimetry of an epithermal neutron beam; field size and phantom size dependence of the dose distribution. To be published.Google Scholar
- 7.C.P.J. Raaijmakers, L. Dewit, M.W. Konijnenberg, B.J. Mijnheer, R.L. Moss and F. Stecher-Rasmussen. A semi-empirical method of treatment planning for boron neutron capture therapy, in: “Boron Neutron Capture Therapy; Toward Clinical Trials of Glioma Treatment,” D. Gabel. R. Moss, ed., Plenum Press, New York, 1992, pp. 93–100.Google Scholar