Retrospective Comparative Study on Dose Gradients and Peripheral Dose Management in Advanced Radiotherapy Systems.

Area of Science:

• Radiation Oncology
• Medical Physics
• Neurosurgery

Background:

• Advanced radiotherapy techniques are crucial for treating complex brain tumors.
• Minimizing dose spillage and achieving steep dose gradients are key to reducing toxicity.
• Comparing different linear accelerator (linac) technologies is essential for optimizing treatment delivery.

Purpose of the Study:

• To compare dose gradients and peripheral dose spillage among C-Arm Linac, Ring Gantry, and Robotic Arm Linac.
• To evaluate the performance of these modalities in delivering precise radiation doses to brain tumors.
• To inform clinical decisions regarding the selection of radiotherapy technology.

Main Methods:

• Retrospective analysis of 110 patients with multi-lesion brain tumors treated with stereotactic radiotherapy.
• Treatment planning and dosimetric analysis across C-Arm Linac (TrueBeam STx), Ring Gantry (Radixact®), and Robotic Arm Linac (CyberKnife®).
• Analysis of gradient index (GI5-GI50) and conformity following ICRU 91 guidelines, with phantom verification.

Main Results:

• Robotic Arm Linac demonstrated the steepest dose gradients and lowest GI values, indicating superior precision and minimal low-dose spillage (P < 0.05).
• C-Arm Linac and Ring Gantry showed comparable performance at higher GI values, with the Ring Gantry offering broader coverage for larger targets.
• Phantom validation confirmed modality-specific advantages in dose distribution.

Conclusions:

• Robotic Arm Linac is optimal for precise treatments requiring stringent organ-at-risk sparing.
• C-Arm Linac and Ring Gantry are suitable for broader dose coverage in complex cases.
• Findings guide modality selection based on tumor characteristics and clinical needs for improved patient outcomes.