Treatment planning optimization for multiple arcs stereotactic radiosurgery using a linear accelerator

Area of Science:

• Medical Physics
• Radiation Oncology
• Neurosurgery

Background:

• Multiarc stereotactic radiosurgery (SRS) is a precise technique for intracranial tumor irradiation.
• Conventional SRS treatment planning relies on time-consuming, suboptimal trial-and-error methods.
• Nonconformal dose distributions arise from using uniform collimator sizes across all treatment arcs.

Purpose of the Study:

• To introduce an optimized method for three-dimensional (3D) treatment dose planning in multiarc SRS.
• To evaluate the efficacy of optimizing collimator size and isocenter coordinates for improved dose conformity.

Main Methods:

• A derivative-free optimization algorithm was employed to determine optimal collimator sizes for individual arcs.
• The optimization process also determined the ideal 3D coordinates for radiation isocenters.
• This approach contrasts with traditional methods using fixed collimator sizes and manual adjustments.

Main Results:

• Optimized treatment plans demonstrated superior conformity of the 90% isodose curve to tumor volumes.
• Conventional methods resulted in either incomplete tumor coverage or excessive irradiation of normal tissues.
• Evaluations included artificial spherical and ellipsoidal tumors, as well as one actual clinical tumor case.

Conclusions:

• Optimizing individual arc collimator sizes and isocenter locations significantly enhances dose conformity in multiarc SRS.
• The proposed optimization method yields superior treatment plans compared to conventional approaches.
• Improved conformity leads to better tumor targeting and reduced exposure of healthy brain tissue.