ORIGINAL RESEARCH article
Front. Oncol.
Sec. Radiation Oncology
Volume 15 - 2025 | doi: 10.3389/fonc.2025.1568959
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 3 articles
Stereotactic core ablative radiation therapy (SCART) for small hypoxic tumors: Impact of dosimetric approaches and consequent optimization strategy on the context of spatially fractionated radiation therapy
Provisionally accepted
Zhengzheng Xu1,2*
Salim Balik1,2Kaley Woods1,2Andrew Lim1,2Jason Ye1,2Eric Chang1,2
Kristopher Lyons3Lijun Ma1,2
Zhilei Shen1,2
Hualin Zhang1,2- 1Keck School of Medicine, University of Southern California, Los Angeles, United States
- 2Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States
- 3University Hospitals Seidman Cancer Center, Cleveland, Georgia, United States
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Purpose: The stereotactic core ablative radiation therapy (SCART) delivers a single ablative dose core to the central hypoxic part while keeping low doses to the periphery of the tumor. This study evaluated the dosimetric impacts of various SCART planning approaches for small targets on the context of spatially fractionated radiation therapy (SFRT).Methods and Materials: Using an anthropomorphic phantom, SCART plans were generated for cases with one spherical target, two spherical targets, one spherical and one irregular-shaped target, and four spherical targets, respectively. All the spherical targets were 3 cm in diameter. One third of the central gross target volume (GTV) volume was contoured as the GTV_central to represent the hypoxic tumor volume, while the rest was contoured as GTV_peripheral for low dose (3Gy) coverage. Within each GTV, a small sphere with diameter ranging from 0.5cm to 1.5cm was contoured at the center to represent the volume of single high dose core (V_SHDC). For the irregular-shaped target, both spherical (V_SHDC) and conformal (V_cSHDC) high dose cores were used for comparisons. A single fraction of 15Gy was prescribed to V_SHDC in all plans.Single and dual isocenter technique was used for case of two targets. Dosimetric parameters which were usually used to describe SFRT plans were compared for all SCART plans. The pros and cons of all planning approaches were elaborated.Results: The mean dose to V_SHDC was 17.0±0.7Gy. For multiple-target SCART plans, the VGTVp<3Gy ranged from 35.1 to 63.6%. No significant difference in dosimetric parameters was found between plans using single isocenter and dual isocenters. For the irregularly shaped target, the cV_SHDC improved the equivalent uniform dose (EUD) while the low dose (3Gy) coverage (VGTVp<3Gy) decreased. The average D10/D90 of all the plans was 8.0±1.7. SCART used 1 cm diameter V_SHDC (volume ratio of V_SHDC/GTV was within 2-5%) demonstrated better dosimetric balance between high dose coverage for GTV_central and low dose coverage for GTV_peripheral.SCART for small targets is feasible, the plans demonstrated a comparable dosimetric quality as seen in the traditional SFRT plans for bulky tumors.
Keywords: Stereotactic core ablative radiation therapy, spatially fractionated radiation therapy, lattice therapy, Small target, VMAT
Received: 31 Jan 2025; Accepted: 01 Sep 2025.
Copyright: © 2025 Xu, Balik, Woods, Lim, Ye, Chang, Lyons, Ma, Shen and Zhang. 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: Zhengzheng Xu, Keck School of Medicine, University of Southern California, Los Angeles, United States
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