3D tomodosimetry using scintillating fibers: proof-of-concept

We present a novel, high-resolution 3D dosimeter based on the tomographic acquisition of the dose using long scintillating fibers. This study aims to demonstrate the concept of the dosimeter with simulated acquisitions using the input dose from Pinnacle3. The dosimeter is composed of concentric, cylindrical planes in which scintillating fibers are placed at different angles between the fiber and the cylindrical plane. Upon a complete rotation of the device around its central axis, the incident dose distribution on the cylindrical planes can be reconstructed using tomographic reconstruction algorithm. The 3D dose in the dosimeter can then be interpolated from the cylindrical 2D dose distributions. Using a simulated acquisition composed of two concentric cylindrical planes of 36 and 32 fibers each, we achieve below 1% local dose difference between the reconstructed 3D dose and the expected dose from Pinnacle3 in the high dose, low gradient region of the volume encompassed inside the innermost cylindrical plane. The results show the potential of the method to perform high-resolution 3D dose measurements of both square and IMRT fields.