SU-E-T-533: Evaluating Effective Source Position Corrections during Modeling with Pinnacle Version 9.2 Software for...

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• Advanced radiation therapy techniques like SBRT and VMAT require precise dose calculations, especially for small radiation fields.
• Flattening Filter Free (FFF) beams introduce complexities in dose modeling due to steep dose gradients and non-uniform penumbra.
• Accurate modeling in treatment planning systems (TPS) is crucial for effective and safe radiation delivery.

Purpose of the Study:

• To evaluate the accuracy of the ADAC/Pinnacle TPS in modeling and calculating doses for small field FFF photon beams.
• To compare the performance of Pinnacle v9.0 and v9.2 in small field dosimetry.
• To assess the impact of TPS upgrades on the accuracy of advanced radiotherapy planning.

Main Methods:

• Photon beam data was modeled using Pinnacle v9.0, generating flattened and FFF models for 6MV and 10MV energies.
• Models were fine-tuned using a 5x5 cm² field to prioritize small field accuracy.
• Comparisons were made between Pinnacle v9.0 and the upgraded v9.2, including patient-specific dosimetric calculations.

Main Results:

• Pinnacle v9.0 exhibited difficulties in accurately modeling small fields, particularly showing asymmetry in the penumbra region for both flattened and FFF beams.
• The Pinnacle v9.2 upgrade successfully eliminated small field asymmetries and improved penumbra region calculations.
• Preliminary results indicated that Pinnacle v9.2 can develop accurate beam models when optimized for small fields.

Conclusions:

• Pinnacle v9.2 demonstrates superior accuracy in modeling small field FFF beams compared to Pinnacle v9.0.
• The improvements in Pinnacle v9.2 are reflected in patient-specific dosimetric data, enhancing treatment planning for complex cases.
• The study highlights the importance of TPS version and model optimization for advanced radiotherapy techniques.