GammaTile® Brachytherapy as Spatially Fractionated Radiation Therapy for Postoperative Brain Cancer: A Paradigm for Precision Intracranial Radiotherapy
- 1Department of Radiation Oncology, University of Southern California, Los Angeles, CA 90033, USA
- 2Department of Medical Affairs, GT Medical Technologies, Inc., Tempe, AZ 85281, USA
- 3Department of Neurological Surgery, University of Southern California, Los Angeles, CA 90033, USA
Abstract
Purpose: Tile-based radiation therapy (TBRT) delivers adjuvant radiation to brain tumor beds using evenly spaced cesium-131 (Cs-131) sources in collagen tiles. This study evaluated TBRT as spatially fractionated radiation therapy (SFRT) across tumor sizes and source counts. Methods and Materials: Dose distributions were generated from postoperative CT scans for 18 patients treated with TBRT, using 10–32 implanted Cs-131 sources per case (median, 20). The resection cavity (RC) was contoured on CT with registered postoperative T1-weighted MRI guidance. CTV_5mm was defined as the RC plus a 5 mm expansion excluding skull and surgical tract, and CTV_5mm_Eval as CTV_5mm minus the RC. Both volumes were analyzed using SFRT dose metrics from the Radiosurgery Society SFRT/Flash working group white paper, and planar high-dose core number density (HCND_A) was used to characterize TBRT spatial fractionation. Results: The mean dose indices of D5 (dose covering 5% of the target volume), D10, D50, D90, D95 and D100 were 175.8 ± 43.3, 148.8 ± 35.1, 86.7 ± 18.5, 56.1 ± 10.5, 50.2 ± 9.0 and 33.4 ± 7.2 Gy for the CTV_5mm_Eval, respectively. The heterogeneity indices, represented by the ratio of D5/D95 and D10/D90, were 3.5 ± 0.6 and 2.7 ± 0.4, respectively, which were in the range of the linac-based Lattice therapy. HCND_A was a constant, TBRT delivered one high dose core for every 1 cm2 of tumor bed. All dose metrics in both the CTV_5mm and CTV_5mm_Eval were largely consistent across all plans. Conclusions: TBRT produced heterogeneous dose distributions comparable to conventional SFRT. A 60 Gy TBRT nominal prescription dose approximated the SFRT D90, or valley dose of the 5 mm expansion target volume, suggesting TBRT may provide an SFRT platform for tile-accessible cancers.
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BibTeX
@article{zhang2026gammatile,
title = {{GammaTile® Brachytherapy as Spatially Fractionated Radiation Therapy for Postoperative Brain Cancer: A Paradigm for Precision Intracranial Radiotherapy}},
author = {Hualin Zhang and Nguyen Phuong Dang and Jason C. Ye and Adam Garsa and Aram S. Modrek and Zhilei Liu Shen and Salim Balik and Zhengzheng Xu and Kaley Woods and Adam C. Turner and David G. Brachman and Thomas Chen and Gabriel Zada and Eric L. Chang},
journal = {Cancers},
year = {2026},
month = oct,
doi = {10.3390/cancers18193201},
url = {https://europepmc.org/article/PMC/PMC13663927},
note = {CC BY},
}
RIS
TY - JOUR
TI - GammaTile® Brachytherapy as Spatially Fractionated Radiation Therapy for Postoperative Brain Cancer: A Paradigm for Precision Intracranial Radiotherapy
AU - Hualin Zhang
AU - Nguyen Phuong Dang
AU - Jason C. Ye
AU - Adam Garsa
AU - Aram S. Modrek
AU - Zhilei Liu Shen
AU - Salim Balik
AU - Zhengzheng Xu
AU - Kaley Woods
AU - Adam C. Turner
AU - David G. Brachman
AU - Thomas Chen
AU - Gabriel Zada
AU - Eric L. Chang
PY - 2026
DA - 2026/10/01
JO - Cancers
DO - 10.3390/cancers18193201
UR - https://europepmc.org/article/PMC/PMC13663927
AB - Purpose: Tile-based radiation therapy (TBRT) delivers adjuvant radiation to brain tumor beds using evenly spaced cesium-131 (Cs-131) sources in collagen tiles. This study evaluated TBRT as spatially fractionated radiation therapy (SFRT) across tumor sizes and source counts. Methods and Materials: Dose distributions were generated from postoperative CT scans for 18 patients treated with TBRT, using 10–32 implanted Cs-131 sources per case (median, 20). The resection cavity (RC) was contoured on CT with registered postoperative T1-weighted MRI guidance. CTV_5mm was defined as the RC plus a 5 mm expansion excluding skull and surgical tract, and CTV_5mm_Eval as CTV_5mm minus the RC. Both volumes were analyzed using SFRT dose metrics from the Radiosurgery Society SFRT/Flash working group white paper, and planar high-dose core number density (HCND_A) was used to characterize TBRT spatial fractionation. Results: The mean dose indices of D5 (dose covering 5% of the target volume), D10, D50, D90, D95 and D100 were 175.8 ± 43.3, 148.8 ± 35.1, 86.7 ± 18.5, 56.1 ± 10.5, 50.2 ± 9.0 and 33.4 ± 7.2 Gy for the CTV_5mm_Eval, respectively. The heterogeneity indices, represented by the ratio of D5/D95 and D10/D90, were 3.5 ± 0.6 and 2.7 ± 0.4, respectively, which were in the range of the linac-based Lattice therapy. HCND_A was a constant, TBRT delivered one high dose core for every 1 cm2 of tumor bed. All dose metrics in both the CTV_5mm and CTV_5mm_Eval were largely consistent across all plans. Conclusions: TBRT produced heterogeneous dose distributions comparable to conventional SFRT. A 60 Gy TBRT nominal prescription dose approximated the SFRT D90, or valley dose of the 5 mm expansion target volume, suggesting TBRT may provide an SFRT platform for tile-accessible cancers.
SN - 2072-6694
ER -