A mask-compatible, radiolucent, 8-channel head and neck receive array for MRI-guided radiotherapy treatments and pre-treatment simulation
Zijlema, Stefan Emiel; Breimer, Wico; Gosselink, Mark W J M; Bruijnen, Tom; Arteaga de Castro, Catalina S; Tijssen, Rob H N; Lagendijk, Jan J W; Philippens, Marielle E P; Van den Berg, Cornelis A T
(2022) Physics in medicine and biology, volume 67, issue 13, pp. 1 - 14
(Article)
Abstract
Immobilization masks are used to prevent patient movement during head and neck (H&N) radiotherapy. Motion restriction is beneficial both during treatment, as well as in the pre-treatment simulation phase, where magnetic resonance imaging (MRI) is often used for target definition. However, the shape and size of the immobilization masks hinder
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the use of regular, close-fitting MRI receive arrays. In this work, we developed a mask-compatible 8-channel H&N array that consists of a single-channel baseplate, on which the mask can be secured, and a flexible 7-channel anterior element that follows the shape of the mask. The latter uses high impedance coils to achieve its flexibility and radiolucency. A fully-functional prototype was manufactured, its radiolucency was characterized, and the gain in imaging performance with respect to current clinical setups was quantified. Dosimetry measurements showed an overall dose change of -0.3%. Small, local deviations were up to -2.7% but had no clinically significant impact on a full treatment plan, as gamma pass rates (3%/3 mm) only slightly reduced from 97.9% to 97.6% (clinical acceptance criterion: ≥95%). The proposed H&N array improved the imaging performance with respect to three clinical setups. The H&N array more than doubled (+123%) and tripled (+246%) the signal-to-noise ratio with respect to the clinical MRI-simulation and MR-linac setups, respectively. G-factors were also lower with the proposed H&N array. The improved imaging performance resulted in a clearly visible signal-to-noise ratio improvement of clinically used TSE and DWI acquisitions. In conclusion, the 8-channel H&N array improves the imaging performance of MRI-simulation and MR-linac acquisitions, while dosimetry suggests that no clinically significant dose changes are induced.
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Keywords: Head, Humans, MR-linac, MRI-guided radiotherapy, MRI-simulation, Magnetic Resonance Imaging, Particle Accelerators, Phantoms, Imaging, Radiotherapy, Image-Guided, Signal-To-Noise Ratio, head and neck, mask-compatible, radiolucent receive array, Radiological and Ultrasound Technology, Radiology Nuclear Medicine and imaging, Research Support, Non-U.S. Gov't, Journal Article
ISSN: 0031-9155
Publisher: IOP Publishing Ltd.
Note: Funding Information: This work is part of the research program HTSM with project number 15354, which is financed by the Netherlands Organization for Scientific Research (NWO) and Philips Healthcare. Publisher Copyright: © 2022 Institute of Physics and Engineering in Medicine.
(Peer reviewed)