Rthp-26. evaluating a single isocenter radiation approach to treat multiple brain metastases (bm) with stereotactic radiosurgery (srs): impact of lesion number, location and volume on treatment plan results

In an attempt to diminution the sequelae of whole brain irradiation, multiple BM are more frequently approached with SRS rather than whole brain irradiation. However, the individual treatment of each lesion with a multi-isocenter, serial approach is cumbersome and time consuming. We elected to investigate a single-isocenter volumetric modulated arc therapy (VMAT) planning and treatment technique for radiosurgical treatment of multiple BM. The emphasize was placed on tumor number, size, volume and location and its impact on the treatment plan. Treatment plan data of 10 patients with multiple BM were selected for a prospective comparative study investigating single-isocenter arc-based VMAT or multiple static beam approach, treating in parallel, using manual weighting to compensate for different dose and target volume. Arcs or static beams were planned for simultaneous irradiation of multiple targets to maximize beam on-time efficiency. To accommodate varying dose prescriptions, selected arcs were re-irradiated for dose escalation. Beam weights were adjusted until all prescription constraints were encountered. For comparative purposes, VMAT plans were generated utilizing an established single-isocenter, 3-5 arc planning template. All plans were compared by means of Paddick conformity index, Radiation Therapy Oncology Group Conformity Index, gradient index, and the normal brain volume receiving 12Gy. Monitor units and delivery time (evaluation with Mobius3d) were charted for each...
Source: Neuro-Oncology - Category: Cancer & Oncology Authors: Tags: RADIATION THERAPY Source Type: research