A preliminary study on a multiresolution-level inverse planning approach for Gamma Knife radiosurgery

Area of Science:

• Medical Physics
• Radiosurgery
• Radiation Oncology

Background:

• Manual forward planning for Gamma Knife (GK) radiosurgery is complex due to numerous plan variables.
• Existing inverse planning methods often predetermine isocenter locations, potentially limiting global plan optimization.
• This limitation necessitates exploring advanced inverse planning strategies for improved GK treatment efficacy.

Purpose of the Study:

• To introduce and evaluate a novel multiresolution-level (MRL) inverse planning approach for Gamma Knife radiosurgery.
• To address the challenge of optimizing isocenter locations and beam parameters for more comprehensive treatment planning.
• To compare the MRL approach against manual forward planning and standard Leksell GammaPlan (LGP) inverse planning.

Main Methods:

• The MRL approach iteratively optimizes isocenter candidates at progressively finer resolutions.
• Beam-on time for each collimator and sector is optimized at each isocenter candidate.
• Isocenters from previous rounds and their neighbors inform candidate selection in subsequent rounds, followed by shot sequencing.

Main Results:

• The MRL approach demonstrated superior plan quality in single-target cases, showing higher selectivity and lower gradient index.
• Significant reductions in brainstem D_0.1cc dose and total beam-on time were observed with the MRL method.
• For a multi-target case, the MRL approach yielded higher selectivity and a lower gradient index, with comparable beam-on time.

Conclusions:

• The multiresolution-level inverse planning approach is effective and feasible for Gamma Knife radiosurgery.
• This method offers a promising alternative to conventional planning techniques, potentially improving treatment outcomes.
• Further validation confirms the MRL approach's superiority over standard methods, even when optimizing existing isocenters.