TY - JOUR
T1 - Initial Feasibility and Clinical Implementation of Daily MR-Guided Adaptive Head and Neck Cancer Radiation Therapy on a 1.5T MR-Linac System
T2 - Prospective R-IDEAL 2a/2b Systematic Clinical Evaluation of Technical Innovation
AU - MR-Linac Consortium Head and Neck Tumor Site Group
AU - McDonald, Brigid A.
AU - Vedam, Sastry
AU - Yang, Jinzhong
AU - Wang, Jihong
AU - Castillo, Pamela
AU - Lee, Belinda
AU - Sobremonte, Angela
AU - Ahmed, Sara
AU - Ding, Yao
AU - Mohamed, Abdallah S.R.
AU - Balter, Peter
AU - Hughes, Neil
AU - Thorwarth, Daniela
AU - Nachbar, Marcel
AU - Philippens, Marielle E.P.
AU - Terhaard, Chris H.J.
AU - Zips, Daniel
AU - Böke, Simon
AU - Awan, Musaddiq J.
AU - Christodouleas, John
AU - Fuller, Clifton D.
N1 - Publisher Copyright:
© 2020 The Authors
PY - 2021/4/1
Y1 - 2021/4/1
N2 - Purpose: This prospective study is, to our knowledge, the first report of daily adaptive radiation therapy (ART) for head and neck cancer (HNC) using a 1.5T magnetic resonance imaging-linear accelerator (MR-linac) with particular focus on safety and feasibility and dosimetric results of an online rigid registration-based adapt to position (ATP) workflow. Methods and Materials: Ten patients with HNC received daily ART on a 1.5T/7MV MR-linac, 6 using ATP only and 4 using ATP with 1 offline adapt-to-shape replan. Setup variability with custom immobilization masks was assessed by calculating the mean systematic error (M), standard deviation of the systematic error (Σ), and standard deviation of the random error (σ) of the isocenter shifts. Quality assurance was performed with a cylindrical diode array using 3%/3 mm γ criteria. Adaptive treatment plans were summed for each patient to compare the delivered dose with the planned dose from the reference plan. The impact of dosimetric variability between adaptive fractions on the summation plan doses was assessed by tracking the number of optimization constraint violations at each individual fraction. Results: The random errors (mm) for the x, y, and z isocenter shifts, respectively, were M = –0.3, 0.7, 0.1; Σ = 3.3, 2.6, 1.4; and σ = 1.7, 2.9, 1.0. The median (range) γ pass rate was 99.9% (90.9%-100%). The differences between the reference and summation plan doses were –0.61% to 1.78% for the clinical target volume and –11.74% to 8.11% for organs at risk (OARs), although an increase greater than 2% in OAR dose only occurred in 3 cases, each for a single OAR. All cases had at least 2 fractions with 1 or more constraint violations. However, in nearly all instances, constraints were still met in the summation plan despite multiple single-fraction violations. Conclusions: Daily ART on a 1.5T MR-linac using an online ATP workflow is safe and clinically feasible for HNC and results in delivered doses consistent with planned doses.
AB - Purpose: This prospective study is, to our knowledge, the first report of daily adaptive radiation therapy (ART) for head and neck cancer (HNC) using a 1.5T magnetic resonance imaging-linear accelerator (MR-linac) with particular focus on safety and feasibility and dosimetric results of an online rigid registration-based adapt to position (ATP) workflow. Methods and Materials: Ten patients with HNC received daily ART on a 1.5T/7MV MR-linac, 6 using ATP only and 4 using ATP with 1 offline adapt-to-shape replan. Setup variability with custom immobilization masks was assessed by calculating the mean systematic error (M), standard deviation of the systematic error (Σ), and standard deviation of the random error (σ) of the isocenter shifts. Quality assurance was performed with a cylindrical diode array using 3%/3 mm γ criteria. Adaptive treatment plans were summed for each patient to compare the delivered dose with the planned dose from the reference plan. The impact of dosimetric variability between adaptive fractions on the summation plan doses was assessed by tracking the number of optimization constraint violations at each individual fraction. Results: The random errors (mm) for the x, y, and z isocenter shifts, respectively, were M = –0.3, 0.7, 0.1; Σ = 3.3, 2.6, 1.4; and σ = 1.7, 2.9, 1.0. The median (range) γ pass rate was 99.9% (90.9%-100%). The differences between the reference and summation plan doses were –0.61% to 1.78% for the clinical target volume and –11.74% to 8.11% for organs at risk (OARs), although an increase greater than 2% in OAR dose only occurred in 3 cases, each for a single OAR. All cases had at least 2 fractions with 1 or more constraint violations. However, in nearly all instances, constraints were still met in the summation plan despite multiple single-fraction violations. Conclusions: Daily ART on a 1.5T MR-linac using an online ATP workflow is safe and clinically feasible for HNC and results in delivered doses consistent with planned doses.
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U2 - 10.1016/j.ijrobp.2020.12.015
DO - 10.1016/j.ijrobp.2020.12.015
M3 - Article
C2 - 33340604
AN - SCOPUS:85100063236
SN - 0360-3016
VL - 109
SP - 1606
EP - 1618
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 5
ER -