Dosimetric impact of baseline shift plan in a magnetic resonance linear accelerator according to target motion and plan characteristics.
- 1Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract
Purpose
In this study, the dosimetric effect of baseline shift (BLS) in a magnetic resonance linear accelerator was investigated and compared with adapt-to-position (ATP), adapt-to-shape (ATS), and an uncorrected plan without adaptation.Methods
In a simulation dataset consisting of 30 patients (10 prostate, 10 liver, 10 pancreatic), all structures were rigidly shifted by 1, 3, 5, and 10 mm separately in the superior-inferior and posterior directions, and four plans (ATS reoptimization, ATP reoptimization, BLS using the segment aperture morphing algorithm, and an uncorrected plan without adaptation) were generated for each shift condition. Planning target volume (PTV) coverage and PTV maximum dose (Dmax) were then compared. The dosimetric effects of BLS on the targets and organs at risk (OARs) under non-rigid anatomic changes were also evaluated using a clinical dataset based on magnetic resonance imaging acquired during treatment.Results
In the simulation analysis of superior-inferior shifts, target coverage using BLS was comparable to that using ATS and ATP across all disease sites and improved compared with that using the uncorrected plan. For posterior shifts, target coverage remained comparable to that using ATS and ATP; however, BLS increased the PTV Dmax at all posterior shift magnitudes (1-10 mm) in prostate and pancreatic cases, with limited increases in liver cases. In the clinical dataset, OAR doses upon left-right or anterior-posterior displacement were greater using BLS than using ATP, ATS, and uncorrected plans in the prostate and pancreatic cases, with limited increases in the liver cases.Conclusions
The dosimetric impact of BLS relies on motion direction and plan characteristics. BLS was stable for superior-inferior shifts, whereas posterior shifts may increase PTV hotspots and OAR doses. Therefore, clinical application of BLS should consider motion direction and plan design rather than applying a uniform strategy.
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BibTeX
@article{tanaka2026dosimetric,
title = {{Dosimetric impact of baseline shift plan in a magnetic resonance linear accelerator according to target motion and plan characteristics.}},
author = {Shohei Tanaka and Noriyuki Kadoya and Yoshiyuki Takahashi and Seiya Koga and Yoshiyuki Katsuta and Kazuhiro Arai and Taichi Hoshino and Yushan Xiao and Wingyi Lee and Noriyoshi Takahashi and Rei Umezawa and Keiichi Jingu},
journal = {Journal of applied clinical medical physics},
year = {2026},
month = oct,
doi = {10.1002/acm2.70861},
url = {https://europepmc.org/article/MED/42900567},
note = {CC BY},
}
RIS
TY - JOUR
TI - Dosimetric impact of baseline shift plan in a magnetic resonance linear accelerator according to target motion and plan characteristics.
AU - Shohei Tanaka
AU - Noriyuki Kadoya
AU - Yoshiyuki Takahashi
AU - Seiya Koga
AU - Yoshiyuki Katsuta
AU - Kazuhiro Arai
AU - Taichi Hoshino
AU - Yushan Xiao
AU - Wingyi Lee
AU - Noriyoshi Takahashi
AU - Rei Umezawa
AU - Keiichi Jingu
PY - 2026
DA - 2026/10/30
JO - Journal of applied clinical medical physics
DO - 10.1002/acm2.70861
UR - https://europepmc.org/article/MED/42900567
AB - Purpose In this study, the dosimetric effect of baseline shift (BLS) in a magnetic resonance linear accelerator was investigated and compared with adapt-to-position (ATP), adapt-to-shape (ATS), and an uncorrected plan without adaptation.Methods In a simulation dataset consisting of 30 patients (10 prostate, 10 liver, 10 pancreatic), all structures were rigidly shifted by 1, 3, 5, and 10 mm separately in the superior-inferior and posterior directions, and four plans (ATS reoptimization, ATP reoptimization, BLS using the segment aperture morphing algorithm, and an uncorrected plan without adaptation) were generated for each shift condition. Planning target volume (PTV) coverage and PTV maximum dose (Dmax) were then compared. The dosimetric effects of BLS on the targets and organs at risk (OARs) under non-rigid anatomic changes were also evaluated using a clinical dataset based on magnetic resonance imaging acquired during treatment.Results In the simulation analysis of superior-inferior shifts, target coverage using BLS was comparable to that using ATS and ATP across all disease sites and improved compared with that using the uncorrected plan. For posterior shifts, target coverage remained comparable to that using ATS and ATP; however, BLS increased the PTV Dmax at all posterior shift magnitudes (1-10 mm) in prostate and pancreatic cases, with limited increases in liver cases. In the clinical dataset, OAR doses upon left-right or anterior-posterior displacement were greater using BLS than using ATP, ATS, and uncorrected plans in the prostate and pancreatic cases, with limited increases in the liver cases.Conclusions The dosimetric impact of BLS relies on motion direction and plan characteristics. BLS was stable for superior-inferior shifts, whereas posterior shifts may increase PTV hotspots and OAR doses. Therefore, clinical application of BLS should consider motion direction and plan design rather than applying a uniform strategy.
SN - 1526-9914
ER -