Dosimetry for in vitro assessment of targeted alpha therapy

by Tibaux Jacquet

Abstract: Targeted alpha therapy (TAT) is a method of cancer treatment based on the action of a specific radiolabeled molecule, i.e. an alpha emitter linked with a molecule that will target the desired area. The choice of using alpha particles is based on the fact that their LET is higher than the one of beta particles, and therefore their range is about a few tens of micrometers in the body. This allows to limit the dose received by the healthy cells in the vicinity. However, this extreme locality can become a disadvantage during in-vitro studies. Indeed, the spatial distribution of radionuclides in the culture medium must be known precisely to know the dose received by these cells. Measuring the dose with accuracy allows to compare the different treatment methods and thus affirm their efficiency.

The main goal of this internship was to study a device allowing the dosimetric calculation of irradiated cells in culture wells. The experimental device is based on the use of a silicon semiconductor diode underneath a cell culture well in which are placed radioelements. The diode records the energy spectrum emitted through the well. The first part of the work was the characterization of the measurement chain (repeatability, reproductibility etc…). Then to characterize the spatial distribution of ²²³Ra in culture wells, the energy spectra were acquired and deconvoluted using Monte-Carlo simulations. The first results about the inhomogeneity of radioelements in the wells tend to show the adequacy with a previous study.