A new Gamma Knife radiosurgery paradigm: tomosurgery

Area of Science:

• Medical Physics
• Radiation Oncology
• Neurosurgery

Background:

• Leksell Gamma Knife (LGK) is a stereotactic radiosurgery tool for treating intracranial lesions.
• Current LGK treatment planning is manual and time-consuming.
• Optimizing dose delivery for complex brain tumors remains a challenge.

Purpose of the Study:

• To propose and simulate an automated inverse treatment planning and continuous dose delivery approach for LGK, termed Tomosurgery.
• To evaluate the efficacy of Tomosurgery in improving treatment plan quality and reducing planning time compared to manual LGK planning.
• To assess the impact of Tomosurgery on dose distribution within tumors and critical structures.

Main Methods:

• Developed a two-stage inverse treatment planning algorithm for Tomosurgery.
• Simulated Tomosurgery plans for 11 patients with brain tumors previously treated with manual LGK.
• Compared Tomosurgery plans against manually generated LGK plans, analyzing dose standard deviation, conformality, and critical structure sparing (V20, V30).

Main Results:

• Tomosurgery demonstrated significant improvements in dose standard deviation and conformality for lesions without critical structures.
• For cases with critical structures, overall dose-volume histograms improved, though direct sparing metrics showed borderline significance.
• Treatment planning time was substantially reduced, from 1-3 hours for manual planning to 5-35 minutes for Tomosurgery.

Conclusions:

• LGK Tomosurgery offers a promising approach to accelerate treatment planning and enhance treatment quality for brain tumors.
• The method shows particular benefit for large or geometrically complex lesions.
• Further investigation is needed to optimize delivery time, especially when using smaller collimators for extensive lesions.