@article{3115312,
    title = "Fast, three-dimensional, MR Imaging for polymer gel dosimetric
applications involving high dose and steep dose gradients",
    author = "Sandilos, Panagiotis and Baras, Panagiotis and Georgiou, Evangelos and and Dardoufas, Konstantinos and Karaiskos, Pantelis and Papagiannis, and Panagiotis and Paschalis, Theodoros and Tatsis, Elias and Torrens, and Michael and Vlahos, Lampros",
    journal = "NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION
A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT",
    year = "2006",
    volume = "569",
    number = "2, SI",
    pages = "572-576",
    publisher = "ELSEVIER SCIENCE BV",
    doi = "10.1016/j.nima.2006.08.148",
    keywords = "polymer gel dosimetry; multiple spin echo (CPMG); turbo spin echo (TSE)",
    abstract = "Polymer gels constitute water equivalent integrating detectors, which,
combined with magnetic resonance imaging (MRI), can provide accurate
three dimensional (3D) dose distributions in contemporary radiotherapy
applications where the small field dimensions and steep dose gradients
induce limitations to conventional dosimeters. One of the main obstacles
for adapting the method for routine use in the clinical setting is the
cost effectiveness of the MRI readout method. Currently, optimized
Carr-Purcell-Meiboom-Gill (CPMG) multiple spin echo imaging pulse
sequences are commonly used which however result in long imaging times.
This work evaluates the efficiency of 3D, dual-echo, k-space segmented
turbo spin echo (TSE) scanning sequences for accurate dosimetry with
sub-millimetre spatial resolution in strenuous radiation therapy
applications. PABIG polymer gel dosimeters were irradiated with an
Ir-192 High Dose Rate brachytherapy source, the 4 mm and 8 mm collimator
helmets of a gamma knife unit and a custom made x-knife collimator of 1
cm diameter. Profile and dose distribution measurements using TSE are
benchmarked against corresponding findings obtained by the commonly
used, but time consuming, CPMG sequence as well as treatment planning
calculations, Monte Carlo (MC) simulations and film measurements. The
implementation of a high Turbo factor was found to provide comparable
accuracy, allowing a 64-fold MRI scan acceleration compared to
conventional multi-echo sequences. The availability of TSE sequences in
typical MRI installations greatly facilitates the introduction of
polymer gel dosimetry in the clinical environment as a practicable tool
for the determination of full 3D dose distributions in contemporary
radiotherapy applications. (c) 2006 Elsevier B.V. All rights reserved."
}