Dosimetry of swallowed non absorbed 99mTc radiopharmaceuticals in pediatric patients

Area of Science:

• Medical Physics
• Pediatric Nuclear Medicine
• Radiopharmaceutical Dosimetry

Background:

• Accurate absorbed dose calculation is crucial for pediatric patients undergoing radiopharmaceutical procedures.
• Existing models for gastrointestinal (GI) tract dosimetry often simplify radionuclide transit.
• Technetium-99m (99mTc) labeled non-absorbable compounds are frequently used in pediatric diagnostics.

Purpose of the Study:

• To develop and present a novel computational model for deriving absorbed radiation dose in pediatric patients.
• To specifically address the dosimetry of non-absorbable 99mTc compounds within the pediatric GI tract.
• To compare the results of the novel model with existing dosimetry models.

Main Methods:

• A new computational model was developed to simulate continuous distal motion of radionuclides through the GI tract.
• The model incorporates published S values for dose calculation.
• Absorbed doses were calculated for pediatric patients across various age groups.

Main Results:

• The novel model provides calculated absorbed doses comparable to or lower than previously published values.
• Significant differences in calculated absorbed doses were observed in the large gut compared to older models.
• The large gut was identified as the critical organ for absorbed dose in this scenario.

Conclusions:

• The developed model offers a more physiologically accurate representation of radionuclide transit in the pediatric GI tract.
• The refined dosimetry calculations may impact radiation safety assessments for pediatric patients.
• The large intestine remains a critical organ for absorbed dose from non-absorbable 99mTc compounds in children.