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Updated: Apr 16, 2026

Dosimetry for Cell Irradiation using Orthovoltage 40-300 kV X-Ray Facilities
Published on: February 20, 2021
Model-based versus specific dosimetry in diagnostic context: comparison of three dosimetric approaches
S Marcatili1, D Villoing1, T Mauxion1
1Inserm, UMR1037 CRCT, Toulouse F-31000, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, Toulouse F-31000, France.
Accurate internal dosimetry in nuclear medicine diagnostics is crucial. This study found that patient-specific Monte Carlo simulations provide more precise absorbed dose calculations compared to standard lookup table models, highlighting potential biases in current methods.
Area of Science:
- Nuclear Medicine
- Medical Physics
- Radiological Dosimetry
Background:
- Legal requirements mandate dosimetric assessment of radiotracers.
- Diagnostic dosimetry often relies on approximated models (ICRP, MIRD), potentially impacting accuracy.
- Refined dosimetry approaches are needed for improved patient safety and treatment planning.
Purpose of the Study:
- To evaluate if a more refined dosimetry approach can be implemented in nuclear medicine diagnostics.
- To compare patient-specific Monte Carlo simulations with commercial software for absorbed dose calculations.
- To analyze the impact of different dosimetry algorithms on calculated absorbed doses.
Main Methods:
- Absorbed doses to organs were calculated in six healthy volunteers who received (18)F-flutemetamol.
- Patient-specific 3D PET/CT scans were analyzed using an in-house Monte Carlo (MC) application (GATE).
- GATE-derived doses were compared to those from commercial software (OLINDA/EXM, STRATOS).
Main Results:
- Monte Carlo (GATE) calculations yielded higher absorbed doses than OLINDA/EXM (average ratio 1.38).
- Significant discrepancies were observed for the thyroid (average GATE/OLINDA ratio 1.97).
- Differences between GATE and STRATOS were even larger (average ratio 2.51).
Conclusions:
- The choice of absorbed dose calculation algorithm significantly impacts dosimetry results in nuclear medicine.
- Patient-specific Monte Carlo simulations offer a more refined approach compared to standard models.
- Potential biases in diagnostic dosimetry necessitate the use of advanced calculation methods.
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