Measurement techniques, modeling strategies and pitfalls to avoid when implementing a mini MLC in a non dedicated...

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Investigating the Pinnacle treatment planning system for intracranial stereotactic radiotherapy.
• Assessing the feasibility of precise dose computation using the collapsed cone engine.

Purpose of the Study:

• To evaluate the accuracy of dose calculation for stereotactic treatments with the Moduleaf mini-MLC on an Elekta accelerator.
• To compare automatic and manual modeling in the Pinnacle system.

Main Methods:

• Commissioning the Moduleaf using a diamond detector and cylindrical chambers for dose rate corrected data.
• Implementing both automatic and manual modeling techniques within the Pinnacle system.

Main Results:

• Automatic modeling led to dose errors up to 10%, deemed clinically relevant.
• Manual modeling in Pinnacle achieved a 2%/2 mm agreement between modeled data and measurements for clinical fields.

Conclusions:

• The collapsed cone algorithm demonstrates acceptable accuracy for single-fraction stereotactic treatments.
• Manual modeling is crucial for achieving precise dose computation in these clinical scenarios.