Sci-Thur PM: YIS - 05: Tomographic dosimetry using scintillating fibers and its application to 2D and 3D dosimetry

To present the proof of concept and the experimental validation of tomographic dosimetry (tomodosimetry), where a tomographic acquisition of the incident deposited dose is performed using long scintillating fibers.

2D tomodosimetry: 50 long scintillating fibers were aligned on a 20cm diameter disk inside a 30cm diameter masonite phantom. 3D tomodosimetry: 128 long scintillating fibers of various orientation were simulated on the surface of two cylindrical regions of radius 7.5 and 3.75cm inside a 20cm diameter, 20cm long cylindrical phantom. In both case, the dose projections were acquire each 5 degrees over a 180 degrees (2D) or 360 degrees (3D) rotation of the device, and the dose in each scintillating fiber plane was reconstructed using a total variation minimization reconstruction iterative algorithm at a resolution of 1×1mm² . The 3D dose was obtained by interpolating between in each cylindrical plane in the 3D prototype.

3%/3mm gamma tests conducted in the isocentre plane for both configurations achieved a success rate of more than 99% of the dose pixels in the region over 50% of the maximum dose. Absolute dose differences in the high dose low gradient region of each scintillating fiber plane were on average below 1% for the 2D configuration and below 1.3% for the 3D configuration.

This work illustrates the potential and capacity of scintillating fiber based 2D and 3D tomodosimeters. The presented methodology allows for millimeter resolution dosimetry in a whole 2D plane or 3D volumes in real-time using only a limited number of detectors.