Specification of radiation quality in fast neutron therapy: microdosimetric and radiobiological approach.
Specification of radiation quality is an important issue in fast neutron therapy since the biological effectiveness of the beams varies to a large extent with neutron energy. It must meet specific criteria, mainly derived from the accuracy requirement for absorbed dose delivery. A first approach to this problem consists in identifying physical parameters that can be related to Relative Biological Effectiveness (RBE) and which describe the beam production technique (e.g. neutron-producing reaction, p + Be or d + Be, energy of the incident particle). A second is based on microdosimetry, which provides a description of the secondary radiation components to which the biological consequences of irradiations are more directly correlated. A third approach consists in experimental RBE determinations in reference conditions: intestinal crypt regeneration in mice after irradiation to the whole body with single doses is proposed as a standard biological system for radiobiological calibrations of clinical fast neutron beams. Dosimetric, microdosimetric and radiobiological intercomparisons are encouraged since they provide a homogeneous set of data which facilitate the exchange of clinical information. They also constitute a basis for the clinical RBE approach and an overall check of the irradiation procedure. Therefore they should be recommended in every non-conventional radiation therapy facility.
Catholic University of Louvain, Radiobiology and Radioprotection Laboratory, Brussels, Belgium.
J
J
Gueulette
H G
HG
Menzel
P
P
Pihet
A
A
Wambersie
D000818:Animals; D005214:Fast Neutrons / Q000627:therapeutic use*; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012062:Relative Biological Effectiveness