Whole Three-Dimensional Dosimetry of Carbon Ion Beams with an MRI-Based Nanocomposite Fricke Gel Dosimeter Using Rapid T1 Mapping Method.

Shinya Mizukami,Takahiro Mizoguchi,Nobuhisa Fukunishi,Kenichi L Ishikawa,Takuya Maeyama,Yusuke Watanabe,Tsutomu Gomi,Hideyuki Takei,Hidetake Hara,Shigekazu Fukuda

doi:10.3390/gels7040233

Shinya Mizukami, Takahiro Mizoguchi + Show 8 more

Open Access

https://doi.org/10.3390/gels7040233

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Abstract

MRI-based gel dosimeters are attractive systems for the evaluation of complex dose distributions in radiotherapy. In particular, the nanocomposite Fricke gel dosimeter is one among a few dosimeters capable of accurately evaluating the dose distribution of heavy ion beams. In contrast, reduction of the scanning time is a challenging issue for the acquisition of three-dimensional volume data. In this study, we investigated a three-dimensional dose distribution measurement method for heavy ion beams using variable flip angle (VFA), which is expected to significantly reduce the MRI scanning time. Our findings clarified that the whole three-dimensional dose distribution could be evaluated within the conventional imaging time (20 min) and quality of one cross-section.

Highlights

In radiotherapy, it is very important to improve the accuracy of the radiation dose based on the three-dimensional (3D) shape and position of the tumor target, maximizing the dose to the target while minimizing damage to the adjacent normal tissue
This map was constructed from 40 images that were taken along the axes of the beams
The volume rendering (VR) images [57] are shown in Figure 1b for better viewing by the user

Summary

Introduction

It is very important to improve the accuracy of the radiation dose based on the three-dimensional (3D) shape and position of the tumor target, maximizing the dose to the target while minimizing damage to the adjacent normal tissue To fulfill this need using linear accelerators in external radiotherapy, irradiation techniques, such as intensity-modulated radiotherapy (IMRT), stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT), are performed in many clinical facilities. While irradiation technology is advancing, dose administration in clinical settings needs to be of high precision and accuracy when performing complex processes such as tumor imaging and treatment planning This is especially true when it comes to heavy ion and proton beams because a slight setup error can highly affect the dose distribution in the patients’ body, and cause significant errors. Dose distribution measurements in carbon beams must be performed carefully because the lateral dose distribution is steep as a result of less multiple scattering

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