Multicomponent mathematical model for tumor volume calculation with setup error using single-isocenter stereotactic...

Area of Science:

• Radiation Oncology
• Medical Physics
• Mathematical Modeling

Background:

• Stereotactic radiotherapy (SRT) is a crucial treatment for brain metastases.
• Patient setup errors, particularly six degrees-of-freedom (6DoF), can impact treatment efficacy.
• Understanding tumor residual volume is key to optimizing SRT outcomes.

Purpose of the Study:

• To evaluate tumor residual volumes in SRT considering 6DoF patient setup errors.
• To analyze the impact of tumor size, isocenter distance, and setup errors on residual volumes.
• To determine distances satisfying specific residual volume tolerance rates.

Main Methods:

• Utilized a multicomponent mathematical model for single-isocenter SRT simulations.
• Simulated spherical gross tumor volumes (GTVs) of 1.0, 2.0, and 3.0 cm diameters.
• Incorporated 6DoF patient setup errors (translation and rotation) and varied GTV-isocenter distances (d).

Main Results:

• Optimized tumor growth model parameters using non-small cell lung cancer cell line data (A549, NCI-H460).
• Calculated GTV residual volumes based on physical dose, GTV size, d, and 6DoF setup errors.
• Determined that larger tolerance values for residual volume allowed for longer distances (d).

Conclusions:

• Smaller GTV size, larger distance (d), and greater 6DoF setup errors require shorter distances to satisfy tolerance values.
• The findings are crucial for optimizing single-isocenter SRT planning for brain metastases.
• Mathematical modeling provides valuable insights into managing setup uncertainties in radiotherapy.