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Novel, full 3D scintillation dosimetry using a static plenoptic camera
Author(s) -
Goulet Mathieu,
Rilling Madison,
Gingras Luc,
Beddar Sam,
Beaulieu Luc,
Archambault Louis
Publication year - 2014
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 - 10.1118/1.4884036
Subject(s) - dosimetry , scintillation , medical imaging , optics , medical physics , computer graphics (images) , nuclear medicine , computer science , physics , artificial intelligence , medicine , detector
Purpose: Patient‐specific quality assurance (QA) of dynamic radiotherapy delivery would gain from being performed using a 3D dosimeter. However, 3D dosimeters, such as gels, have many disadvantages limiting to quality assurance, such as tedious read‐out procedures and poor reproducibility. The purpose of this work is to develop and validate a novel type of high resolution 3D dosimeter based on the real‐time light acquisition of a plastic scintillator volume using a plenoptic camera. This dosimeter would allow for the QA of dynamic radiation therapy techniques such as intensity‐modulated radiation therapy (IMRT) or volumetric‐modulated arc therapy (VMAT). Methods: A Raytrix R5 plenoptic camera was used to image a 10 × 10 × 10 cm 3 EJ‐260 plastic scintillator embedded inside an acrylic phantom at a rate of one acquisition per second. The scintillator volume was irradiated with both an IMRT and VMAT treatment plan on a Clinac iX linear accelerator. The 3D light distribution emitted by the scintillator volume was reconstructed at a 2 mm resolution in all dimensions by back‐projecting the light collected by each pixel of the light‐field camera using an iterative reconstruction algorithm. The latter was constrained by a beam's eye view projection of the incident dose acquired using the portal imager integrated with the linac and by physical consideration of the dose behavior as a function of depth in the phantom. Results: The absolute dose difference between the reconstructed 3D dose and the expected dose calculated using the treatment planning software Pinnacle 3 was on average below 1.5% of the maximum dose for both integrated IMRT and VMAT deliveries, and below 3% for each individual IMRT incidences. Dose agreement between the reconstructed 3D dose and a radiochromic film acquisition in the same experimental phantom was on average within 2.1% and 1.2% of the maximum recorded dose for the IMRT and VMAT delivery, respectively. Conclusions: Using plenoptic camera technology, the authors were able to perform millimeter resolution, water‐equivalent dosimetry of an IMRT and VMAT plan over a whole 3D volume. Since no moving parts are required in the dosimeter, the incident dose distribution can be acquired as a function of time, thus enabling the validation of static and dynamic radiation delivery with photons, electrons, and heavier ions.