When the heavily ionizing alpha particle traverses the crystal the ionization causes local charge-trapping defects. These defects are “frozen” in and act like fossilized markers of alpha particle track.
An irradiated crystal is subsequently scanned (in three dimensions) with a laser of appropriate wavelength. When the laser strikes a defect, the laser light is scattered and detected. In this way, a 3D picture of the alpha track is obtained and the position and angle can be reconstructed. Moreover, the laser restores the crystal defect and the crystal is ready to go again for future detections.
This technique can be used to determine the microdosimetry of sectioned tissue since the reconstructed alpha track can be extrapolated back to the tissue to determine the exact origin. Simulations of Am241 uniformly distributed in the cytoplasm of a 3D cell culture were used to determine the error in survival resulting from ignoring the microdosimetry. In some sense, the resolution is “too good” since the error in survival is far below the biological uncertainties of cell cycle RBE, OER and the targeting efficiency unknowns of alpha radionuclide carriers.
Presented By: Jasper J. M. Kouwenberg from Radioisotopes for Health, Delft University of Technology, Delft, the Netherlands.
Written By: William Carithers, Lawrence Berkeley National Laboratory
at the 10th International Symposium on Targeted Alpha Therapy (TAT-10) May 31 - June 1, 2017 - Kanazawa, Japan.