ORIGINAL RESEARCH article
Front. Oncol.
Sec. Radiation Oncology
Volume 15 - 2025 | doi: 10.3389/fonc.2025.1680342
This article is part of the Research TopicRadiation Spatial Fractionation—A novel approach to integrate Physics, Biology, and Immunology for high therapeutic index radiotherapyView all 5 articles
Novel Volumetric Modulated Arc Therapy Approach for Lattice Radiation Therapy for Bulky Liver Tumors
Provisionally accepted
Christine V Chung*
Saurabh S Nair
Meena S KhanCallistus I Nguyen
Rachael Marianne Martin-PaulpeterEthan Bernard Ludmir
Laurence Edward Court
Joshua Scott Niedzielski*- University of Texas MD Anderson Cancer Center, Houston, United States
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Purpose: Lattice radiation therapy (LRT) is a type of spatially fractionated radiation therapy that has emerged as an effective treatment approach for bulky solid tumors. RapidArc Dynamic (RAD) is a novel beam delivery approach that may be advantageous for LRT. The purpose of this in silico study was to evaluate and compare a novel RAD-based LRT approach (RAD-LRT) with conventional volumetric modulated arc therapy (VMAT)-based LRT (VMAT-LRT). Methods: Twenty patients with bulky liver tumors treated with RT were retrospectively identified. VMAT-LRT and RAD-LRT plans were generated for all patients. Lattice spheres were placed in a standardized hexagonal pattern with alternating high-dose spheres (vertex tumor volume high [VTVH], analogous to the peak dose) and low-dose control spheres (vertex tumor volume low [VTVL], analogous to the valley dose). Gross tumor volumes (GTVs) <1,000 cm3 and GTVs ≥1,000 cm3 were planned with 1.0-cm-diameter spheres (n=10) and 1.5-cm-diameter sphere (n=10), respectively. A prescription dose of 20 Gy to 80% of the VTVH was utilized. LRT dose metrics (e.g., peak-to-valley dose ratios, VTVH D80, VTVL Dmean) were calculated and were compared using paired Wilcoxon sign-ranked test. Planning efficiency was assessed by evaluating planning structures, planning time, and number of treatment fields. Results: For all 20 cases, RAD-LRT achieved superior plan quality than VMAT-LRT, indicated by similar prescription dose coverage (group mean, VTVH D80: 20.40 Gy for VMAT-LRT, 20.50 Gy for RAD-LRT) but significantly lower valley dose (group mean, VTVL mean dose: 3.40 Gy for VMAT-LRT, 2.20 Gy for RAD-LRT, p<0.0001). Compared to VMAT-LRT, RAD-LRT required fewer planning structures (mean±SD, 9±1 for VMAT-LRT, 4±1 for RAD-LRT), less planning time (26±8 min for VMAT-LRT, 18±11 min for RAD-LRT), and fewer treatment beams (5±1 arcs for VMAT-LRT, 1 arc with 4±1 static ports for RAD-LRT). RAD-LRT also had significantly higher peak-to-valley dose ratios (group mean, VTVH/VTVL D90 ratio: 8.92 for VMAT-LRT, 18.20 for RAD-LRT, p<0.0001). Conclusion: RAD may offer a unique approach to Lattice RT. RAD-LRT generated high quality plans with notable treatment planning efficiency, allowing for creation of quality plans without extensive planning time and LRT expertise.
Keywords: spatially fractionated radiation therapy, lattice radiation therapy, VMAT, RapidArc Dynamic, liver cancer, Hepatic cancer, bulky tumors, Peak-to-Valley Dose Ratio
Received: 05 Aug 2025; Accepted: 30 Sep 2025.
Copyright: © 2025 Chung, Nair, Khan, Nguyen, Martin-Paulpeter, Ludmir, Court and Niedzielski. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Christine V Chung, cchung2@mdanderson.org
Joshua Scott Niedzielski, jsniedzielski@mdanderson.org
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