9 Reporting in Brachytherapy: Dose and Volume Specification

164 Reporting in Brachytherapy

Active source length The active source length is defined as the distance from the most proximal to most distal end of the radioactive material contained in the source line: e.g., (physical) length of wire, seed train, ribbon source. For a moving source, the length is defined as the distance between its extreme positions. • strength (activity) of the sources, specified according to the recommendations of section 4. • distribution of the activity within the source(s) (uniform or differential loading, etc.) (10,22,58). 3.2 Source pattern ● number of sources or source lines; ● separation between source lines and between planes, or separation between the guides, if a single moving source is used; • geometrical pattern formed by the sources (e.g., triangles, squares), for interstitial implants or utero-vaginal source spacing, where relevant; • the surfaces in which the implant lies, i.e., planes or curved surfaces; • whether crossing sources are placed at one or more ends of a group of linear sources. 3.3 Applicator • catheter, material of the inactive vector used to carry the radioactive sources (e.g., flexible or rigid); • dimensions (diameter and length); • whether rigid templates are used at one or both ends; • centering device for the catheter (e.g., for intrabronchial or endovascular applications); • fixation; • shielding (high atomic number material, e.g., for the rectum in cervix treatment, or the mandibula in lip or oral cavity interstitial applications; • for cervix treatment, fully rigid applicator (or not), consequently fixed known geometry (or not) of the complete applicator device; • rigid uterine source with fixed curvature (or not) ; • connection between vaginal and uterine applicators, i.e., fixed, loose (semi-fixed), free ; ● type of vaginal sources: ovoids (size and separation), line sources (number and orientation), special sources (box, ring, mould, etc.). 3.4 Type of afterloading and source movement ● manual afterloading; ● remote afterloading; (sufficient relevant information should be given on the mechanical system of afterloading) (1,36,49,50,110,112,113); ● stepping source; ● oscillating source (an accurate description of the source movements is necessary to derive the time-dose pattern at the different points in the PTV or organs at risk, see section 5, p. 168). NB: Description of the source(s), applicator and technique is facilitated when the types/models have been published. The complete reference of the publication is then often sufficient. When appropriate,