Technological quality requirements for stereotactic radiotherapy: expert review group consensus from the DGMP Working Group for Physics and Technology in Stereotactic Radiotherapy - Schmitt, Daniela; Blanck, Oliver; Gauer, Tobias; Fix, Michael K.; Brunner, Thomas B.; Fleckenstein, Jens; Loutfi-Krauss, Britta; Manser, Peter; Werner, René; Wilhelm, Maria-Lisa; Baus, Wolfgang W.; Moustakis, Christos (Strahlentherapie und Onkologie, 2020)