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A Treatment Planning Strategy of Single Isocenter Multiple Target Stereotactic Radiosurgery for Multiple Brain Metastases Using Dynamic Conformal Arc Technique

S Kim1*, (1) Baylor Scott & White Health, Temple, TX


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: To establish a treatment planning method in creating Single Isocenter Multiple Target (SIMT) Stereotactic Radiosurgery (SRS) treatment plans for multiple brain metastases patients using a dynamic conformal arc (DCA) technique in order to improve the robustness of the treatment delivery and to compare it with volumetric-modulated arc planning (VMAT) technique.

Methods: We employed two treatment planning systems (TPS) to perform the SIMT SRS treatment planning with DCA. Eclipse TPS (v 13.6, Varian Medical Systems) was mainly used to set the isocenter location, groups of multiple targets and to define the optimal arc angles. iPlan TPS was used to get the optimal arc weight of each individual arc per each target. Once all the optimal arc weights were determined for all the targets from iPlan, the process of defining optimal arc ranges including beam aperture modification which was manually performed in Eclipse in order to synchronize an individual target dose to other targets. We assumed that there is no significant dose effect from out-of-field beams. Five non-coplanar arcs were employed in both DCA and VMAT treatment plans. Dose distribution was calculated with AAA algorithm in Eclipse. For three multiple brain metastases patients, the DCA plans were compared in dosimetry as well as the robustness of treatment delivery with VMAT treatment plans using RapidArc which were used for treatments.

Results: It was found that this study’s DCA treatment planning method was able to provide dosimetrically equivalent SIMT treatment plan qualities compared to VMAT plans with less monitor units (MU) and more robust treatment delivery for multiple brain metastases due to the removal of intensity modulation which is unnecessary for small targets.

Conclusion: Proposed treatment planning strategy produces SIMT SRS treatment plans dosimetrically equivalent to VMAT plans with more efficient and robust treatment delivery in multiple brain metastases SRS cases.


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