MRI is still playing a major part in polymer gel dosimetry and improvements have been realised, notably concerning the optimization in the determination of T_(2) using multi-echo sequences and by the introduction of turbo spin echo sequences adapted to polymer gel dosimeters. Both these imperatives were required to meet the needs in high precision polymer gel dosimetry. As of yet, there is no consensus in the utilization of MRI in polymer gel dosimetry. This is due, in part, in the sequences that are commercially available from different vendors, and the varying level of flexibility that these offer. It appears that turbo spin echo sequences hold great promise for the time-efficient evaluation of gels, but more work is required in order to fully characterize the image integrity and consideration must be given to the efficiency of these methods compared to standard CPMG sequences. Also, it appears that the optimization of turbo spin-echo sequences with respect to the number of echoes, the effective echo time, and the number of images is still needed. A similar conclusion is reached concerning the spatial integrity of these sequences.
展开▼
