A robustness check procedure for hypofractionated Gamma Knife radiosurgery

Area of Science:

• Medical Physics
• Radiation Oncology
• Neurosurgery

Background:

• Interfractional patient motion is a challenge in hypofractionated brain radiosurgery.
• Accurate dose delivery is critical for effective treatment and minimizing side effects.

Purpose of the Study:

• To develop and evaluate a robustness treatment planning check procedure.
• To assess the dosimetric impact of residual target shifts in hypofractionated Gamma Knife radiosurgery (GKRS).

Main Methods:

• Residual patient shifts were determined post-immobilization during simulation.
• A quality assurance procedure was created to simulate residual target shifts in treatment plans.
• The procedure was tested on 10 hypofractionated GKRS cases.

Main Results:

• Maximum residual shifts were under 1 mm.
• Target coverage varied by 1.9% ± 2.2% and selectivity by 3.6% ± 2.5% with incorporated shifts.
• Additional 0.5 mm shifts reduced target coverage by up to 7% and caused dose distribution variations.

Conclusions:

• A pretreatment robustness check procedure for hypofractionated GKRS was successfully developed and demonstrated.
• This method can evaluate dosimetric effects of patient shifts.
• Further research will establish maximum tolerance levels for patient-specific assessments.