Inverse planning in Gamma Knife radiosurgery: A comparative planning study

Area of Science:

• Neurosurgery
• Radiation Oncology
• Medical Physics

Background:

• Stereotactic radiosurgery (SRS) is a key treatment for various brain pathologies.
• Manual forward planning for SRS can be time-consuming and may not always achieve optimal dosimetry.
• Advancements in planning software aim to improve treatment efficacy and safety.

Purpose of the Study:

• To evaluate the benefits of inverse planning using Leksell Gamma Knife® (LGK) Lightning software.
• To compare LGK Lightning's inverse planning against traditional manual forward planning.
• To assess dosimetry and efficiency improvements for different brain tumor types.

Main Methods:

• Retrospective analysis of 38 patients with metastases, vestibular schwannomas, and meningiomas treated with LGK Icon™.
• Generation of inverse (inv) and inverse full coverage (fc) plans using LGK Lightning.
• Comparison of treatment plans based on dosimetry and beam on time (BOT).
• Statistical analysis using paired-sample Wilcoxon test and inter-operator variability assessment.

Main Results:

• Inverse and full coverage plans demonstrated improved target coverage (up to 3.6%).
• Enhanced selectivity and significant reductions in organ-at-risk doses were observed (e.g., up to 17.5% for meningiomas).
• Beam on time was reduced (up to 49.5% for benign tumors), and inter-operator variability was minimal.

Conclusions:

• LGK Lightning software facilitates superior LGK treatment plan quality compared to manual forward planning.
• The software leads to reduced beam on time and improved organ-at-risk sparing.
• LGK Lightning ensures consistent treatment plan quality across different users.