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Proceedings Paper

Radiotherapy dosimetry assessment with optical projection tomography
Author(s): Giannis Zacharakis; Antonios Papadakis; Fotini Zacharopoulou; Anikitos Garofalakis; Thomas Maris; Jorge Ripoll
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Paper Abstract

Recent advances in radiotherapy have created the need to develop novel methods for the accurate, three-dimensional assessment of the applied radiation dose during specific radiotherapy plans. Here we present a study based on the use of polymer gel dosimeters in combination with a novel Optical Projection Tomography system, which allows the association of optical properties, namely the attenuation coefficient, to the irradiation dose. Polymer gel dosimeters are polymerized after X-ray irradiation via free radical production during water radiolysis resulting to increased optical opacity as well as change of the nuclear magnetic resonance relaxation times, thus making it possible to study them with both optical and MRI techniques. The optical tomographic system employs a sensitive CCD camera, a rotation stage allowing full 360 degrees rotation and a homogeneous white light source transilluminating the samples. This setup allows the calculation of the optical attenuation coefficient which can then be directly related to the applied radiotherapy dose, as well as the definition of the surface of the sample in space. The experimental procedure involves the recording of transillumination images of the polymer samples in steps of 1 degree to get the desired resolution. Data analysis is performed by back propagating the photons using an inverse Radon transform resulting to the reconstruction of three dimensional images of the attenuation coefficient or equivalently the dose distribution. The sensitivity and dynamic range offered by the technique covers the range of radiotherapy doses in modern clinical practice and are compared with the corresponding achieved with MRI.

Paper Details

Date Published: 12 July 2007
PDF: 7 pages
Proc. SPIE 6629, Diffuse Optical Imaging of Tissue, 66291C (12 July 2007); doi: 10.1117/12.728296
Show Author Affiliations
Giannis Zacharakis, Foundation for Research and Technology Hellas (Greece)
Antonios Papadakis, Univ. Hospital of Heraklion, Univ. of Crete (Greece)
Fotini Zacharopoulou, Univ. Hospital of Heraklion, Univ. of Crete (Greece)
Anikitos Garofalakis, Foundation for Research and Technology Hellas (Greece)
Thomas Maris, Univ. Hospital of Heraklion, Univ. of Crete (Greece)
Jorge Ripoll, Foundation for Research and Technology Hellas (Greece)

Published in SPIE Proceedings Vol. 6629:
Diffuse Optical Imaging of Tissue
Brian W. Pogue; Rinaldo Cubeddu, Editor(s)

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