Design of a positioning system for soft-docking of an intraoperative electron accelerator

A soft-docking system is one of the features of modern intraoperative radiotherapy(IORT) technology. It delivers a single fraction of radiation to the surgically exposed tissue, whilst the treatment head is not in direct contact with the applicator. The aim of this study is to present the design of the positioning system for soft-docking of mobile linear accelerator that is being developed at the National Centre of Nuclear Research in Otwock-Świerk, Poland. Our proposed design includes four red laser beams installed along with the treatment head, and a specially prepared applicator with a pre-drawn reference circle. When the treatment head is correctly positioned, all four laser dots intersect with the circle. Numerical simulation showed that it is possible to minimize misalignment to around 0.5° angular and 1 mm linear with this model.