Effect of Multi-Leaf Collimator Angle Optimization on the Planning Parameters in Intensity-Modulated Radiotherapy for...

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Intensity-modulated radiotherapy (IMRT) is a standard treatment for thoracic tumors.
• Automatic field splitting in IMRT planning can increase treatment time and complexity.
• Multi-leaf collimator (MLC) angle optimization is a potential strategy to mitigate these issues.

Purpose of the Study:

• To evaluate the impact of MLC angle optimization on IMRT planning parameters for thoracic tumors.
• To compare treatment efficiency and safety between standard and optimized MLC angle plans.

Main Methods:

• Retrospective analysis of 42 thoracic tumor patients (esophageal and lung cancer).
• Two IMRT plans were created: one with MLC angle at 0° (automatic field splitting) and another with adjusted MLC angle to avoid field splitting.
• Comparison of homogeneity index (HI), conformity index (CI), organ at risk (OAR) doses, monitor units (MUs), and treatment time; dose verification was performed.

Main Results:

• Both planning methods achieved clinical requirements and similar target dose distributions.
• Adjusting MLC angle significantly reduced MUs and treatment time for both patient groups.
• Significant reductions in lung dose metrics (Dmean, V5Gy, V10Gy, V20Gy) were observed with the optimized MLC angle (P < 0.05).

Conclusions:

• Adjusting MLC angle to prevent automatic field splitting is an effective strategy for thoracic tumors.
• This method significantly reduces MUs and treatment time without compromising target coverage or OAR safety.
• Optimized MLC angle planning enhances efficiency in IMRT for thoracic malignancies.