Treatment planning for MR-guided SBRT of pancreatic tumors on a 1.5 T MR-Linac: A global consensus protocol
Grimbergen, Guus; Eijkelenkamp, Hidde; Snoeren, Louk M.W.; Bahij, Rana; Bernchou, Uffe; van der Bijl, Erik; Heerkens, Hanne D.; Binda, Shawn; Ng, Sylvia S.W.; Bouchart, Christelle; Paquier, Zelda; Brown, Kerryn; Khor, Richard; Chuter, Robert; Freear, Linnéa; Dunlop, Alex; Mitchell, Robert Adam; Erickson, Beth A.; Hall, William A.; Godoy Scripes, Paola; Tyagi, Neelam; de Leon, Jeremiah; Tran, Charles; Oh, Seungjong; Renz, Paul; Shessel, Andrea; Taylor, Edward; Intven, Martijn P.W.; Meijer, Gert J.
(2024) Clinical and translational radiation oncology, volume 47
(Article)
Abstract
Background and purpose: Treatment planning for MR-guided stereotactic body radiotherapy (SBRT) for pancreatic tumors can be challenging, leading to a wide variation of protocols and practices. This study aimed to harmonize treatment planning by developing a consensus planning protocol for MR-guided pancreas SBRT on a 1.5 T MR-Linac. Materials and
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methods: A consortium was founded of thirteen centers that treat pancreatic tumors on a 1.5 T MR-Linac. A phased planning exercise was conducted in which centers iteratively created treatment plans for two cases of pancreatic cancer. Each phase was followed by a meeting where the instructions for the next phase were determined. After three phases, a consensus protocol was reached. Results: In the benchmarking phase (phase I), substantial variation between the SBRT protocols became apparent (for example, the gross tumor volume (GTV) D99% ranged between 36.8 – 53.7 Gy for case 1, 22.6 – 35.5 Gy for case 2). The next phase involved planning according to the same basic dosimetric objectives, constraints, and planning margins (phase II), which led to a large degree of harmonization (GTV D99% range: 47.9–53.6 Gy for case 1, 33.9–36.6 Gy for case 2). In phase III, the final consensus protocol was formulated in a treatment planning system template and again used for treatment planning. This not only resulted in further dosimetric harmonization (GTV D99% range: 48.2–50.9 Gy for case 1, 33.5–36.0 Gy for case 2) but also in less variation of estimated treatment delivery times. Conclusion: A global consensus protocol has been developed for treatment planning for MR-guided pancreatic SBRT on a 1.5 T MR-Linac. Aside from harmonizing the large variation in the current clinical practice, this protocol can provide a starting point for centers that are planning to treat pancreatic tumors on MR-Linac systems.
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Keywords: Consensus protocol, MR-guided SBRT, Pancreatic cancer, Treatment planning, Oncology, Radiology Nuclear Medicine and imaging
ISSN: 2405-6308
Publisher: Elsevier Ireland Ltd
Note: Publisher Copyright: © 2024 The Author(s)
(Peer reviewed)