VMAT

Name (ID): Brain Mets, 4 mets, CT-MR (VSS 06)
Plan or PlanSum ID: HA10m1rc

HyperArc was utilized for this case which means it used a very simplified workflow for planning and delivery.  First the immobilization device is added as a structure model to the patient.  Then, creating a new HyperArc plan walks the user through the process of placing the isocenter of the predefined HyperArc beam set and identifying the target structures and their desired Rx dose.  At that point the Photon Optimizer can be launched automatically which includes preset lower objectives for each target with 100 priority and the HyperArc exclusive SRS NTO (also with 100 priority) which is tuned specifically to enforce a sharp dose falloff and prevent dose bridging of multiple adjacent disparate targets.

Eclipse 15.5+ also features the Automatic Lower Dose Objective (ALDO) which, when enabled in the Photon Optimizer, in the background automatically adjusts dose/priority to keep dose converge on targets near 98%.  Enabling ALDO thereby balances dose received by each target prescribed to the same dose level during optimization.

The plan presented here was created with minimal user interaction during optimization.  ALDO was enabled which did keep target coverage similar during optimization.  However, after final dose calculation there were minor differences in target coverage between some of the most extreme sized targets.  The offsets between requested and resulting calculated doses were noted and the optimizer was restarted with offsets added to the requested target doses.  The offsets were as follows: GTV1-resection 16.2Gy(from 15Gy), GTV2 19Gy, GTV3 18.5Gy, GTV8 18.5Gy, GTV9 18.5Gy, all other optimization objectives were left at their default values (18Gy) with no change made to any priority (all were 100).

Utilizing the ALDO feature resulted in significant time savings as most targets were equally covered after the first optimization and only a single additional optimization was required to create dose offsets in the optimizer for some of the most extreme large and small targets.  The Photon Optimizer calculation option Convergence Mode was set to Extended.

_{Any reference to a "plan study" are simply what the organizers call each case and may not be a "study" in the FDA sense as they may not have been published in a peer reviewed journal.
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