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TU‐A‐BRB‐01: Groundbreaking 2D and 3D Dosimetry Techniques Using Scintillating Fibers and Tomographic Reconstruction
Author(s) -
Goulet M,
Archambault L,
Beaulieu L,
Gingras L
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4735858
Subject(s) - imaging phantom , isocenter , dosimetry , optics , physics , rotation (mathematics) , radius , materials science , nuclear medicine , geometry , mathematics , medicine , computer science , computer security
Purpose : To present the novel concept of tomodosimetry, i.e. the tomographic reconstruction of the dose projections obtained using long scintillating fibers, and its application to 2D and 3D dosimetry. Methods : 2D configuration: 50 scintillating fibers were aligned on a 20cm diameter disk inside a 30cm diameter rotating masonite phantom. 18 dose projections (8 MU each) were measured for each radiation field over a 180 degrees rotation of the phantom. 3D configuration: 128 long scintillating fibers were simulated inside a 20cm diameter, 20cm long cylindrical water‐equivalent phantom. The fibers were placed at various angles on the surface of two cylindrical regions of radius 7.5 and 3.75cm. Using the predicted dose from Pinnacle3, we simulated a 360 degrees rotation of the phantom along its principal axis, collecting the scintillation light from the fibers at each 5 degrees. Both prototypes: the dose in each scintillating fiber plane was reconstructed using a total variation minimization reconstruction iterative algorithm at a resolution of 1×1mm 2 , and was interpolated in the 3D volume between in each cylindrical plane in the 3D prototype. Results : Absolute measured dose differences in the 2D configuration were on average below 1% in the high dose low gradient region of each field. Absolute doses differences calculated inside the inner cylindrical region were on average of 0.5% and 1.3% of the isocenter dose for a 10×10cm 2 field and an IMRT segment, respectively. 3%/3mm gamma tests conducted in both configurations in the isocenter plane achieved a success rate of more than 99% of the dose pixels for the region over 50% of the maximum dose. Conclusions : This work demonstrates the potential of scintillating fiber based tomographic 2D and 3D dosimeters. This methodology allows for millimeter resolution dosimetry in a whole 2D plane or 3D volumes in realtime using only a limited number of detectors.