7 Summary

During past years, the introduction of VMAT and IGRT has improved radiotherapy’s therapeutic ratio in prostate cancer. Tight dose conformance and normal tissue sparing have resulted in plans of increased complexity. Such highly sophisticated plans may become problematic if their complexity exceeds some critical threshold. There is an abundance of aperture-based complexity metrics for VMAT plans in the literature. PCA and MIA suggest both shared and unique informational content among many complexity metrics. The ability to predict VMAT plan complexity from clinical and dosimetric parameters is feasible in principle. Both linear and logistic regression models showed promising outcomes. However, more work is needed to validate their results in larger datasets before being used in production.