Hypofractionated Brain Radiosurgery Utilizing Quasi Dynamic Dose Painting

The idea of dynamic dose painting for stereotactic radiotherapy was first proposed by us in 2009 via developing a 3D lawn-mowing algorithm (https://pubmed.ncbi.nlm.nih.gov/19229095/). With the recent advancements in image-guided hypofractionated beam delivery platforms, a high number of isocenters on the order of 500 may be automatically administered. Such a technical advancement potetially enables a quasi dynamic dose painting (QDDP) approach where a continuous beam trajectory may be mimicked with connected segments of stop-and-shot beam nodes. In this paper, the first-time clinical implementation of QDDP for hypofractionated radiosurgery of large lesions is presented. When compared to conventional treatments via a limited isocenters, QDDP drastically improved the dosing quality of a treatment in terms of target coverage, dose conformality and peripheral dose gradient (which was noted to approach the theoretical optimum for some clinical cases). Technical caveats are plenty for QDDP and will be discussed during the presentation. In conclusion, the concept of dynamic dose painting was demonstratd to be feasible for the first time in clinics. QDDP can be espcially advantageous for treating brain tumors large in size, in the eloquent brain or with diffusive characteristics.