# Multicenter evaluation of planning quality in intracranial stereotactic radiotherapy for brain metastases

## TL;DR

This study evaluated the quality of brain metastases radiotherapy plans across 24 centers, finding high target coverage and adherence to safety limits.

## Contribution

The study provides a multicenter evaluation of SRT planning quality, highlighting consistent adherence to dose constraints despite varied planning strategies.

## Key findings

- Target coverage exceeded 95% across all centers.
- 74% of plans achieved high conformity with a CI < 1.1.
- Non-coplanar plans reduced low-dose brain exposure.

## Abstract

•Target coverage in brain stereotactic planning is more than 95% across 24 centers.•Seventy four percent of plans showing high conformity with conformity index < 1.1.•All plans met brainstem dose limits, and non-coplanar plans reduced low-dose brain.

Target coverage in brain stereotactic planning is more than 95% across 24 centers.

Seventy four percent of plans showing high conformity with conformity index < 1.1.

All plans met brainstem dose limits, and non-coplanar plans reduced low-dose brain.

Stereotactic radiotherapy (SRT) is a standard approach for treating multiple brain metastases. However, variation in planning practices may impact treatment quality. This study assessed planning consistency and dose–volume–based outcomes across radiation oncology centers.

A Computed Tomography (CT) scan of an anthropomorphic phantom with structure set was distributed to participating centers. Each center created SRT plans as for a clinical case. Dose distributions were evaluated based on Planning Target Volume (PTV) coverage (V100% (PTV)), dose to 95% of Gross Target Volume (GTV) volume (D95% (GTV)), maximal PTV dose (Dmax), conformity index (CI), gradient index (GI), brain volume receiving different percentages of the prescribed dose, and doses delivered to 0.035 cm3 and 0.5 cm3 of the brainstem.

Twenty-four centers, using 30 treatment units, submitted plans. The V100% (PTV) ranged from 95% to 100%, with Dmax between 110% and 150% of the prescribed dose. Mean GTV dose ranged from 110% to 135%, and 81% of GTVs had D95% between 110% and 120%. High conformity was achieved in 74% of plans (CI < 1.1), while 67% had a GI between 3.4 and 5. All plans met clinical dose constraints for the brainstem and uninvolved brain.

This interinstitutional comparison demonstrated high plan quality and adherence to critical organ constraints, despite variability in planning strategies. These findings support nationwide planning and quality assurance standards to ensure consistently high-quality SRT.