Microdosimetry modeling with auger emitters in generalized cell geometry

Area of Science:

• Medical physics
• Radiological sciences
• Computational biology

Background:

• Auger electron-emitting radionuclides are used in targeted radionuclide therapy.
• Accurate prediction of cell viability requires detailed microdosimetry, especially for irregular cell shapes.
• Understanding the impact of electron range on cellular dose is crucial for treatment efficacy.

Purpose of the Study:

• To develop and validate a microdosimetry model for predicting cell viability in non-spherical cells irradiated by low-energy auger electrons.
• To compare the therapeutic potential of lutetium-177 (Lu-177) and terbium-161 (Tb-161) for prostate cancer treatment using this model.
• To evaluate the role of short-range auger electrons in determining the relative efficacy of different radionuclides.

Main Methods:

• Developed a microdosimetry model using image-derived cell geometries and distance probability distribution functions (PDFs).
• Calculated radiation dose distributions using Monte Carlo simulations for electron energies below 50 eV.
• Compared computational predictions with experimental cell survival data for LNCaP prostate cancer cells treated with Lu-177 and Tb-161 conjugated to PSMA.

Main Results:

• The microdosimetry model accurately predicted cell viability for irregular cell geometries.
• Terbium-161 (Tb-161) demonstrated higher therapeutic efficiency than lutetium-177 (Lu-177).
• The enhanced efficacy of Tb-161 was attributed to its short-range auger electrons.

Conclusions:

• Imaging-based microdosimetry is a viable approach for predicting cell viability and therapeutic effects.
• Short-range auger electrons play a significant role in the efficacy of targeted radionuclide therapy.
• The developed model can aid in selecting optimal radionuclides for cancer treatment.