TOPAS

TOPAS simulates proton transport using Monte Carlo methods to enable accurate dose calculation and modeling of proton therapy treatment heads and CT-based patient geometries.

Key Features:

• Comprehensive modeling capabilities: Models passive scattering and scanning beam treatment heads and supports CT-based patient geometries for simulation.
• Dose scoring and fluence calculations: Performs dose scoring and fluence calculation for treatment head and patient geometry simulations.
• Four-dimensional simulation: Supports 4D simulations that accommodate temporal variations in beam delivery and patient geometry.
• Phase-space management: Supports saving and restarting phase spaces for particle transport analysis and workflow continuity.

Scientific Applications:

• UCSF eye treatment head modeling: Has been used to model the UCSF eye treatment head for proton therapy simulations.
• MGH stereotactic radiosurgery treatment head: Has been applied to model MGH stereotactic alignment in a radiosurgery treatment head.
• MGH gantry treatment heads: Has been used to model MGH gantry treatment heads in both passive scattering and scanning modes.
• Validation against measurements: Initial validation demonstrated excellent agreement with measured data for beam delivery in 3D and 4D simulations.

Methodology:

TOPAS wraps and extends an established general-purpose Monte Carlo code to implement proton transport, CT-based geometry modeling, dose scoring, fluence calculation, phase-space handling, and four-dimensional simulation.