The AAPM/RSNA physics tutorial for residents: internal radiation dosimetry: principles and applications

Area of Science:

• Nuclear Medicine
• Medical Physics
• Radiation Dosimetry

Background:

• Internal dose calculations are crucial in nuclear medicine for assessing radiation exposure.
• The Medical Internal Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine provides established methodologies.
• Accurate dose calculations are essential for patient safety and effective treatment planning.

Purpose of the Study:

• To outline the standard MIRD schema for internal dose calculations.
• To describe the key components and parameters involved in MIRD calculations.
• To highlight the availability of tools like MIRDose and emerging personalized dosimetry methods.

Main Methods:

• Utilizing the MIRD schema, which employs specific symbols and quantities.
• Incorporating data on emitted energy per decay, absorbed energy fractions, organ masses, and biokinetics.
• Employing standardized human body models (phantoms) and biokinetic models.
• Using the MIRDose computer program for dose calculations.

Main Results:

• The MIRD schema provides a framework for calculating absorbed radiation dose in target organs per radioactive decay in source organs.
• Calculations integrate physical decay, biologic clearance, and energy absorption characteristics.
• MIRDose generates dose tables based on administered activity of radiopharmaceuticals.

Conclusions:

• The MIRD schema is the standard for internal dose calculations in nuclear medicine.
• Standardized models and computational tools facilitate dose estimation.
• Advancements are leading to more individualized patient dose calculations, especially critical for vulnerable populations like pregnant or lactating patients.