# In the pursuit of perfect planning: comparison between Lightning Inverse Planning and GammaPlan Wizard for gamma knife radiosurgery

## TL;DR

This paper compares two Gamma Knife radiosurgery planning tools, Lightning and Wizard, finding that Lightning offers faster planning and better coverage but with trade-offs in selectivity.

## Contribution

The study provides a direct comparison of treatment planning performance between Lightning and Wizard for Gamma Knife radiosurgery.

## Key findings

- Lightning improved coverage by 8% and gradient index by 15% compared to Wizard.
- Lightning reduced planning time by 57% despite using three times more shots.
- Only Lightning with OAR protection met all dose constraints across all plans.

## Abstract

The Lightning® software, was added to the Gamma Knife’s Leksell GammaPlan® as a fully automated inverse planner, differently from the prior software, Wizard®. In this paper we compare their treatment planning capacity and quality.

Thirty-eight cases were compared under four different planning techniques. First, manual forward planning aided by the Wizard® optimization tool. Second, inverse planning with Wizard®. The third and fourth plans used Lightning® with and without consideration for organs at risk (OAR). They were analysed for: planning time, number of shots, coverage, selectivity, gradient index, bean-on time, and OAR dose. Comparison based on pathology was added due to their idiosyncrasies. For quality comparison, dose-volume histograms (DVH) were compared to plans developed under our treatment standards. Tumor’s volume and time to plan were correlated with Pearson’s coefficient.

Lightning® had better coverage (8%) and gradient index (15%) but had 12% decrease in selectivity. Planning and delivery times had a reduction of 57% and 5% respectively, despite having three times the number of shots. Only Lightning® with protection of OAR met the dose constrains in all plans. DVH showed similar plan qualities.

Lightning® allowed the planner to explore different optimization parameters to achieve a plan that suits the clinical problem at hand. It took less time to calculate shots placement, OAR protection and the ideal isodose line than the Wizard®. This can be useful to plan multiple and complex targets at a faster time, increase the patient’s tolerance and, may have a radiobiological advantage by impacting intra-fraction repair.