Targeted alpha therapy with Pb or Ac: Change in RBE from daughter migration.

Targeted α-therapy (TAT) could be delivered early to patients who are at a high-risk for developing brain metastases, targeting the areas of the vasculature where tumor cells are penetrating into the brain. We have utilized a Monte Carlo model representing brain vasculature to calculate physical dose and DNA damage from the α-emitters Ac and Pb. The micron-scale dose distributions from all radioactive decay products were modeled in Geant4, including the eV-scale interactions using the Geant4-DNA models.

Dosimetric evaluation of radionuclides for VCAM-1-targeted radionuclide therapy of early brain metastases.

Unlabelled: Brain metastases develop frequently in patients with breast cancer, and present a pressing therapeutic challenge. Expression of vascular cell adhesion molecule 1 (VCAM-1) is upregulated on brain endothelial cells during the early stages of metastasis and provides a target for the detection and treatment of early brain metastases. The aim of this study was to use a model of early brain metastasis to evaluate the efficacy of α-emitting radionuclides, Tb, At, Pb, Bi and Ac; β-emitting radionuclides, Y, Tb and Lu; and Auger electron (AE)-emitters Ga, Zr, In and I, for targeted radionuclide therapy (TRT).

Radioluminescence from Tc-99m in glass predicts local dose.

The widely-used gamma-emitter Tc-99m has been shown to lead to optical emissions in mice and glass. We investigated the possibility that these emissions are due to the Cerenkov effect and whether the light emitted is proportional to local dose. By using a Geant4 Monte Carlo model matched to an experimental measurement, we show that the light detected by a small animal optical imaging system provides a 2D map of the dose throughout a glass sample.

Monte Carlo simulations support non-Cerenkov radioluminescence production in tissue.

There is experimental evidence for the production of non-Cerenkov radioluminescence in a variety of materials, including tissue. We constructed a Geant4 Monte Carlo simulation of the radiation from P32 and Tc99m interacting in chicken breast and used experimental imaging data to model a scintillation-like emission. The same radioluminescence spectrum is visible from both isotopes and cannot otherwise be explained through fluorescence or filter miscalibration.