9 Reporting in Brachytherapy: Dose and Volume Specification

170 Reporting in Brachytherapy

6.1.3 The Paris System

Fig 6.3 : Iridium-192 wire implant according to the Paris system (single-plane implant). The wires are of equal linear activity, parallel, and arranged in such a way that their centres are in the same plane perpendicular to the direction of the wires (i.e. the central plane, see Fig 6.4). (From Wambersie and Battermann [115])

Fig 6.4: The central plane. In an implant where the source lines are rectilineal, parallel, and of equal length, the central plane is perpendicular to the direction of the source lines and passes throughout their centres. The Mean Central Dose (D m ) is the mean of the local minimum doses D i (I = A, B …) in the plateau region. (A) A single plane implant; (B) a two-plane implant; (C) an actual single-plane implant where sources are not rectilinear: the central plane can be defined as in (A). (From ICRU Report 58 (45).