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Synthetic CT generation using Zero TE MR for head-and-neck radiotherapy

Lookup NU author(s): JJ Wyatt, Dr Hazel McCallum

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2025 The AuthorsBackground and Purpose: MRI-based synthetic CTs (synCTs) show promise to replace planning CT scans in various anatomical regions. However, the head-and-neck region remains challenging because of patient-specific air, bone and soft tissues interfaces and oropharynx cavities. Zero-Echo-Time (ZTE) MRI can be fast and silent, accurately discriminate bone and air, and could potentially lead to high dose calculation accuracy, but is relatively unexplored for the head-and-neck region. Here, we prospectively evaluated the dosimetric accuracy of a novel, fast ZTE sequence for synCT generation. Materials and Methods: The method was developed based on 127 patients and validated in an independent test (n = 17). synCTs were generated using a multi-task 2D U-net from ZTE MRIs (scanning time: 2:33 min (normal scan) or 56 s (accelerated scan)). Clinical treatment plans were recalculated on the synCT. The Hounsfield Units (HU) and dose-volume-histogram metrics were compared between the synCT and CT. Subsequently, synthetic treatment plans were generated to systematically assess dosimetry accuracy in different anatomical regions using dose-volume-histogram metrics. Results: The mean absolute error between the synCT and CT was 94 ± 11 HU inside the patient contour. For the clinical plans, 98.8% of PTV metrics deviated less than 2% between synCT and CT and all OAR metrics deviated less than 1 Gy. The synthetic plans showed larger dose differences depending on the location of the PTV. Conclusions: Excellent dose agreement was found based on clinical plans between the CT and a ZTE-MR-based synCT in the head-and-neck region. Synthetic plans are an important addition to clinical plans to evaluate the dosimetric accuracy of synCT scans.

Publication metadata

Author(s): Lauwers I, Capala M, Kaushik S, Rusko L, Cozzini C, Kleijnen J-P, Wyatt J, McCallum H, Verduijn G, Wiesinger F, Hernandez-Tamames J, Petit S

Publication type: Article

Publication status: Published

Journal: Radiotherapy and Oncology

Year: 2025

Volume: 205

Print publication date: 01/04/2025

Online publication date: 29/01/2025

Acceptance date: 27/01/2025

Date deposited: 17/02/2025

ISSN (print): 0167-8140

ISSN (electronic): 1879-0887

Publisher: Elsevier Ireland Ltd

URL: https://doi.org/10.1016/j.radonc.2025.110762

DOI: 10.1016/j.radonc.2025.110762

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