GMctdospp: Description and validation of a CT dose calculation system

Area of Science:

• Medical Physics
• Computational Imaging
• Radiation Dosimetry

Background:

• Accurate dose estimation in computed tomography (CT) is crucial for patient safety and optimizing imaging protocols.
• Existing Monte Carlo (MC) methods for CT dose calculation can be computationally intensive, limiting their practical application.
• A need exists for efficient, user-friendly, and accessible software for CT dose assessment.

Purpose of the Study:

• To develop a free, user-friendly Monte Carlo (MC)-based software (GMctdospp) for computed tomography (CT) dose estimation.
• To achieve fast computation times for arbitrary simulation scenarios, enabling comfortable handling by researchers.
• To validate the developed software against established methods and experimental measurements.

Main Methods:

• Developed the GMctdospp framework using the EGSnrc system for MC-based phantom and patient dose calculations.
• Modeled a CT scanner, incorporating parameters like half-value layer, beam-shaping filter, z-profile, and tube-current modulation (TCM).
• Validated variance reduction techniques by comparing depth-dose and cross-profile calculations with DOSXYZnrc/EGSnrc and performing phantom measurements.

Main Results:

• Accurate CT scanner modeling was achieved, with TCM scheme validated by dose measurements.
• Calculations showed no systematic differences compared to DOSXYZnrc, and phantom measurements were reproduced within 2% average.
• Significant efficiency improvements (six orders of magnitude) were observed, enabling simulations in 25 seconds with ~0.5% uncertainty.

Conclusions:

• A fast, validated, and benchmarked dose calculation system for CT examinations was successfully developed.
• The GMctdospp framework facilitates easy examination of influences from scan protocols and protection methods.
• The free availability of this software supports advancements in radiation safety research within the scientific community.