MIRD Pamphlet No. 34, Part 1: MIRDct-A Customizable Software Tool for CT Dosimetry

Area of Science:

• Medical Physics
• Radiological Sciences
• Nuclear Medicine

Background:

• Computed tomography (CT) is crucial in diagnostic radiology and hybrid imaging (PET/CT, SPECT/CT).
• CT radiation doses can be significant, necessitating accurate dosimetry for protocol optimization.
• Robust tools are required for patient radiation dose assessment in clinical and research settings.

Purpose of the Study:

• To develop MIRDct, a software tool for organ model-based CT dosimetry and radiation risk assessment.
• To provide accurate dose estimates for radiology and nuclear medicine applications.
• To support CT protocol optimization and regulatory compliance.

Main Methods:

• MIRDct utilizes user-defined patient characteristics, scanner specifications, and technique parameters.
• It employs a library of 24 mesh-type phantoms representing diverse patient populations.
• A precomputed Monte Carlo-based dose-coefficient database enables rapid calculation of various dose metrics.

Main Results:

• MIRDct provides organ-level dose estimates, effective dose, dose-length product, and size-specific dose estimates.
• It calculates risk-related metrics like detriment-weighted dose and lifetime attributable risk.
• Benchmarking showed reasonable agreement with other dosimetry codes (4%-30% differences for effective dose).

Conclusions:

• MIRDct offers a transparent, spreadsheet-based implementation for CT dosimetry and risk assessment.
• The software aids in optimizing CT protocols, enhancing patient safety, and supporting quality assurance.
• MIRDct is a valuable tool for accurate CT dosimetry in clinical practice and research.