title: [The dosage calculation of very small irregular electron irradiation fields. 2. The dosage distribution at the edge of the field].
abstract: Cross beam dose distributions of the small square electron fields (1 x 1 to 6 x 6 cm2), used in the first part of this paper, have been measured at a linac equipped with metal diaphragms attached to a closed cone. They have been used for calculation of the mean square radial displacements sigma 2 of the corresponding pencil beams. Due to complicate electron scattering at the cone and the diaphragm, the pencil beam method could not be used with the simplicity and accuracy desired in practice. Therefore, the therapeutical sufficient field widths, field areas and integral doses have been determined directly from the measured dose distributions, and are represented in dependence from the geometric field size. For small fields we found considerable reductions of these values, which, in practice have to be compensated by enlargement of the geometric field size.
authors.affiliation: Abteilung Strahlentherapie, Universitätsklinikum Freiburg.
authors.forename: V F
authors.initials: VF
authors.lastname: Gutt
authors.forename: K
authors.initials: K
authors.lastname: Kuphal
mesh_terms: D004583:Electrons; D006283:Health Physics; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D011879:Radiotherapy Dosage
vernacular_title: Dosisberechnung sehr kleiner irregulärer Elektronen-Bestrahlungsfelder. Teil 2: Dosisverteilung am Feldrand.