An image-based skeletal dosimetry model for the ICRP reference newborn--internal electron sources

Area of Science:

• Medical Physics
• Radiological Dosimetry
• Pediatric Nuclear Medicine

Background:

• Accurate radiation dosimetry in newborns is critical for pediatric nuclear medicine and radionuclide therapy.
• Existing models may not fully capture the complex skeletal structure and cellularity of newborns.
• Understanding electron transport in developing bone and marrow is essential for risk assessment.

Purpose of the Study:

• To develop a comprehensive electron dosimetry model for newborn skeletal tissues.
• To calculate specific absorbed fractions for key target tissues in the newborn skeleton.
• To provide detailed dose data for electron emissions from various skeletal sources.

Main Methods:

• Utilized the University of Florida newborn hybrid phantom and Pafundi et al.'s skeletal model.
• Employed the EGSnrc-based Paired Image Radiation Transport code.
• Modeled monoenergetic electron emissions (1 keV–10 MeV) from active marrow, bone, and cartilage.

Main Results:

• Reported skeletal-averaged specific absorbed fractions according to the MIRD schema.
• Provided bone-specific values in tabular and graphic formats as electronic annexes.
• Quantified dose contributions to active marrow, shallow marrow, and cartilage from various electron sources.

Conclusions:

• The developed model offers a unique and detailed approach to newborn skeletal electron dosimetry.
• Explicitly accounts for newborn ossification centers, marrow cellularity changes, and bone structure.
• Provides essential data for improving radiation dose estimations in pediatric applications.