Physics Bucharest 2017

Plan quality vs Delivery accuracy - VMAT

Leaf motion constraint

Gamma-analysis

• max distance a MLC leaf can travel between adjacent control points • ensures the deliverability of the optimized plan, but it also impacts the plan quality, delivery accuracy and efficiency • a less restrictive leaf motion constraint ( > 5 mm/deg) results in > plan quality but < accurate dose distribution • g -analysis passing rate from 98% to 80% when the allowable leaf motion increased from 3 to 20 mm/deg.

Chen F et al. Med Phys (38) 2011