A MLC-based inversely optimized 3D spatially fractionated grid radiotherapy technique

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• 3D-conformal-radiotherapy and grid-therapy are established radiation techniques.
• Delivering ablative doses to large tumors presents challenges in sparing surrounding tissues.
• Brachytherapy offers precise dose distribution but has limitations for certain tumor types.

Purpose of the Study:

• To present a novel Multi-Leaf Collimator (MLC)-based, 3D grid-therapy technique.
• To evaluate its dose distribution characteristics and potential for treating large tumors.
• To compare its dose fall-off to traditional radiotherapy methods.

Main Methods:

• Development of an MLC-based 3D grid-therapy technique.
• Simulation and analysis of dose distributions.
• Calculation of dose metrics (D50%) for the target and surrounding regions.

Main Results:

• The technique generates a brachytherapy-like dose distribution.
• Achieved D50% values were 20 Gy for spheres, 9.8 Gy for the target, 5.4 Gy for a 1 cm outer shell, and 2.9 Gy for a 2 cm outer shell.
• Demonstrated a rapid dose fall-off beyond the target volume.

Conclusions:

• The MLC-based 3D grid-therapy is a promising technique for ablative dose delivery.
• It offers a potential strategy for safely treating large tumors with steep dose gradients.
• This approach may enhance therapeutic ratio in radiation oncology.