1999 年 19 巻 4 号 p. 239-251
The scatter factor (SF) formalism which Bjarngard has developed is so constructed that it can be applied to any high-energy photon beam, containing the in-water attenuation coefficient as a variable. However, it has not been confirmed that the SF formalism can reasonably be applied to small depths where longitudinal electron equilibrium does not exist and to small fields where lateral electron equilibrium does not exist. A method has been proposed to obtain reasonable SF data at such small depths and fields using the characteristics of a scatter dose-spread kernel. A 10-MV x-ray scatter dose-spread kernel is given which is produced based on the SF formalism.