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Kanayama N, Ikawa T, Takano K, Arita H, Morimoto M, Hirata T, Ogawa K, Teshima T, Konishi K. Association of increasing gross tumor volume dose with tumor volume reduction and local control in fractionated stereotactic radiosurgery for unresected brain metastases. Radiat Oncol 2024; 19:95. [PMID: 39061079 PMCID: PMC11282845 DOI: 10.1186/s13014-024-02487-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 07/06/2024] [Indexed: 07/28/2024] Open
Abstract
BACKGROUND Fractionated stereotactic radiosurgery (fSRS) is an important treatment strategy for unresected brain metastases. We previously reported that a good volumetric response 6 months after fSRS can be the first step for local control. Few studies have reported the association between gross tumor volume (GTV) dose, volumetric response, and local control in patients treated with the same number of fractions. Therefore, in this study, we aimed to investigate the GTV dose and volumetric response 6 months after fSRS in five daily fractions and identify the predictive GTV dose for local failure (LF) for unresected brain metastasis. METHODS This retrospective study included 115 patients with 241 unresected brain metastases treated using fSRS in five daily fractions at our hospital between January 2013 and April 2022. The median prescription dose was 35 Gy (range, 30-35 Gy) in five fractions. The median follow-up time after fSRS was 16 months (range, 7-66 months). RESULTS GTV D80 > 42 Gy and GTV D98 > 39 Gy were prognostic factors for over 65% volume reduction (odds ratio, 3.68, p < 0.01; odds ratio, 4.68, p < 0.01, respectively). GTV D80 > 42 Gy was also a prognostic factor for LF (hazard ratio, 0.37; p = 0.01). CONCLUSIONS GTV D80 > 42 Gy in five fractions led to better volume reduction and local control. The goal of planning an inhomogeneous dose distribution for fSRS in brain metastases may be to increase the GTV D80 and GTV D98. Further studies on inhomogeneous dose distributions are required.
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Affiliation(s)
- Naoyuki Kanayama
- Department of Radiation Oncology, Osaka International Center Institute, 3-1-69 Otemae, Chuo- ku, Osaka-shi, 541-8567, Osaka, Japan.
| | - Toshiki Ikawa
- Department of Radiation Oncology, Osaka International Center Institute, 3-1-69 Otemae, Chuo- ku, Osaka-shi, 541-8567, Osaka, Japan
| | - Koji Takano
- Department of Neurosurgery, Osaka International Center Institute, 3-1-69 Otemae, Chuo-ku, Osaka-shi, 541-8567, Osaka, Japan
| | - Hideyuki Arita
- Department of Neurosurgery, Osaka International Center Institute, 3-1-69 Otemae, Chuo-ku, Osaka-shi, 541-8567, Osaka, Japan
| | - Masahiro Morimoto
- Department of Radiation Oncology, Osaka International Center Institute, 3-1-69 Otemae, Chuo- ku, Osaka-shi, 541-8567, Osaka, Japan
| | - Takero Hirata
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-shi, 565-0871, Osaka, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-shi, 565-0871, Osaka, Japan
| | - Teruki Teshima
- Osaka Heavy Ion Therapy Center, 3-1-10 Otemae, Chuo-ku, Osaka, Japan
| | - Koji Konishi
- Department of Radiation Oncology, Osaka International Center Institute, 3-1-69 Otemae, Chuo- ku, Osaka-shi, 541-8567, Osaka, Japan
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Ohtakara K, Suzuki K. Consideration of Optimal Evaluation Metrics for Internal Gross Tumor Dose Relevant to Tumor Response in Multi-fraction Stereotactic Radiosurgery of Brain Metastasis. Cureus 2024; 16:e65338. [PMID: 39184769 PMCID: PMC11344629 DOI: 10.7759/cureus.65338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2024] [Indexed: 08/27/2024] Open
Abstract
Introduction In stereotactic radiosurgery (SRS) for brain metastasis (BM), the target dose inhomogeneity remains highly variable among modalities, irradiation techniques, and facilities, which can affect tumor response during and after multi-fraction SRS. Volumetric-modulated arcs (VMAs) can provide a concentrically-layered steep dose increase inside a gross tumor volume (GTV) boundary compared to dynamic conformal arcs. This study was conducted to review the optimal evaluation method for the internal GTV doses relevant to maximal response and local control, specifically to examine the significance of the doses 2 mm and 4 mm inside the GTV boundary in VMA-based SRS. Materials and methods This was a planning study for the clinical scenario of a single BM and targeted 25 GTVs of >0.50 cc, including eight spherical models with diameters of 10-45 mm and 17 clinical BMs (GTV: 0.72-44.33 cc). SRS plans were generated for each GTV using VMA with a 5-mm leaf-width multileaf collimator and the optimization that prioritized the steepness of the dose gradient outside the GTV boundary without any internal dose constraints. The dose prescription and evaluation were based on the GTV D V-0.01 cc, a minimum dose of GTV minus 0.01 cc. Two planning systems were compared for the GTV - 2 mm and GTV - 4 mm structures that were generated by equally reducing 2 mm and 4 mm from the GTV surface. The D eIIVs, a minimum dose of the irradiated isodose volume equivalent to the GTV - 2 mm and GTV - 4 mm, were compared to other common metrics. Results The GTV - 2 mm and GTV - 4 mm volumes differed significantly between the systems. In the spherical GTVs, the irradiated isodose surfaces of GTV D 80% and D 50% corresponded to 0.4-1.6 mm (<2 mm) and 1.0-4.6 mm inside the GTV boundary, respectively. In the 25 GTVs, the GTV - 2 mm coverage with the D eIIV varied from 83.7% to 98.2% (95-98% in 68% of the cases), while the GTV coverage with the GTV - 2 mm D eIIV was 20.2-75.9%. In the 23 GTVs of ≥1.26 cc, the GTV coverage with the GTV - 4 mm D eIIV varied from 1.9% to 55.6% (<50% in 87% of the cases). No significant difference was observed between the GTV D 50% and the GTV - 2 mm D eIIV, while the GTV - 4 mm D eIIV was significantly higher than the GTV D 50%. No significant correlations were observed between the GTV D 50% and the D eIIVs of the GTV - 2 mm and GTV - 4 mm. Conclusions The doses 2 mm and 4 mm inside a GTV have low correlations with the GTV D 50% and may be more relevant to maximal response and local control for SRS of BM. The D eIIV instead of the minimum dose of a fixed % coverage (e.g. D 98%) is suitable for reporting the doses 2 mm and 4 mm inside the GTV boundary in terms of avoiding the over- or under-coverage, with consideration to substantial variability in minus margin addition functions among planning systems. In VMA-based SRS with a steep dose gradient, the doses 2-4 mm inside a GTV decrease significantly as the GTV increases, which can attenuate the excessive dose exposure to the surrounding brain in a large BM due to the GTV shrinkage during multi-fraction SRS.
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Affiliation(s)
- Kazuhiro Ohtakara
- Department of Radiation Oncology, Kainan Hospital Aichi Prefectural Welfare Federation of Agricultural Cooperatives, Yatomi, JPN
- Department of Radiology, Aichi Medical University, Nagakute, JPN
| | - Kojiro Suzuki
- Department of Radiology, Aichi Medical University, Nagakute, JPN
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Sagawa T, Ikawa T, Ohira S, Kanayama N, Ueda Y, Inui S, Miyazaki M, Konishi K. What is the optimal isodose line for stereotactic radiotherapy for single brain metastases using HyperArc? J Appl Clin Med Phys 2024:e14408. [PMID: 38863310 DOI: 10.1002/acm2.14408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 05/04/2024] [Accepted: 05/07/2024] [Indexed: 06/13/2024] Open
Abstract
PURPOSE The study aimed to investigate the optimal isodose line (IDL) in linear accelerator-based stereotactic radiotherapy for single brain metastasis, using HyperArc. We compared the dosimetric parameters for target and normal brain tissue among six plans with different IDLs. METHODS This study included 30 patients with single brain metastasis. We retrospectively generated six plans for each tumor with different IDLs (80%, 70%, 60%, 50%, 40%, and 33%) using HyperArc. All treatment plans were normalized to the prescription dose of 35 Gy in five fractions which was covered by 95% of the planning target volume (PTV), defined by adding a 1.0 mm margin to the gross tumor volume (GTV). The dosimetric parameters were compared among the six plans. RESULTS For GTV > 0.1 cm3, the ratio of brain-GTV volumes receiving 25 Gy to PTV (V25Gy/PTV) was significantly lower at IDL 40%-70% than at IDL 80% and 33% (p < 0.01, retrospectively). For GTV < 0.1 cm3, V25Gy/PTV decreased continuously as IDL decreased. The values of D99% and D80% for GTV increased with decreasing IDL. An IDL of 50% or less was required to achieve D99% of greater than 43 Gy and D80% of greater than 50 Gy. The mean values of D99% and D80% for IDL 50% were 44.3 and 51.9 Gy. CONCLUSION The optimal IDL is 40%-50% for GTV > 0.1 cm3. These lower IDLs could increase D99% and D80% of GTV while lowering V25Gy of normal brain tissue, which may help reduce the risk of radiation necrosis and improve local control.
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Affiliation(s)
- Tomohiro Sagawa
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Toshiki Ikawa
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Shingo Ohira
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Naoyuki Kanayama
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Yoshihiro Ueda
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Shoki Inui
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Masayoshi Miyazaki
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Koji Konishi
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
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Mishra A, Koffler D, Calugaru E, Rowe N, Viswanatha SD, Begley S, Bajaj V, Schulder M, Goenka A. Let's make size not matter: tumor control and toxicity outcomes of hypofractionated Gamma Knife radiosurgery for large brain metastases. J Neurooncol 2023; 163:587-595. [PMID: 37410346 DOI: 10.1007/s11060-023-04365-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/06/2023] [Indexed: 07/07/2023]
Abstract
PURPOSE Management of patients with large brain metastases poses a clinical challenge, with poor local control and high risk of adverse radiation events when treated with single-fraction stereotactic radiosurgery (SF-SRS). Hypofractionated SRS (HF-SRS) may be considered, but clinical data remains limited, particularly with Gamma Knife (GK) radiosurgery. We report our experience with GK to deliver mask-based HF-SRS to brain metastases greater than 10 cc in volume and present our control and toxicity outcomes. METHODS Patients who received hypofractionated GK radiosurgery (HF-GKRS) for the treatment of brain metastases greater than 10 cc between January 2017 and June 2022 were retrospectively identified. Local failure (LF) and adverse radiation events of CTCAE grade 2 or higher (ARE) were identified. Clinical, treatment, and radiological information was collected to identify parameters associated with clinical outcomes. RESULTS Ninety lesions (in 78 patients) greater than 10 cc were identified. The median gross tumor volume was 16.0 cc (range 10.1-56.0 cc). Prior surgical resection was performed on 49 lesions (54.4%). Six- and 12-month LF rates were 7.3% and 17.6%; comparable ARE rates were 1.9% and 6.5%. In multivariate analysis, tumor volume larger than 33.5 cc (p = 0.029) and radioresistant histology (p = 0.047) were associated with increased risk of LF (p = 0.018). Target volume was not associated with increased risk of ARE (p = 0.511). CONCLUSIONS We present our institutional experience treating large brain metastases using mask-based HF-GKRS, representing one of the largest studies implementing this platform and technique. Our LF and ARE compare favorably with the literature, suggesting that target volumes less than 33.5 cc demonstrate excellent control rates with low ARE. Further investigation is needed to optimize treatment technique for larger tumors.
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Affiliation(s)
- Akash Mishra
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
- Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Daniel Koffler
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Emel Calugaru
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Niara Rowe
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Sirisha Devi Viswanatha
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Sabrina Begley
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
- Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Vikram Bajaj
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Michael Schulder
- Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA
| | - Anuj Goenka
- Department of Radiation Oncology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY, USA.
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Ohtakara K, Suzuki K. Modified Dynamic Conformal Arcs With Forward Planning for Radiosurgery of Small Brain Metastasis: Each Double Arc and Different To-and-Fro Leaf Margins to Optimize Dose Gradient Inside and Outside the Gross Tumor Boundary. Cureus 2023; 15:e34831. [PMID: 36919061 PMCID: PMC10008411 DOI: 10.7759/cureus.34831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2023] [Indexed: 02/12/2023] Open
Abstract
Dynamic conformal arcs (DCA) are a widely used technique for stereotactic radiosurgery (SRS) of brain metastases (BM) using a micro-multileaf collimator (mMLC), while the planning design and method considerably vary among institutions. In the usual forward planning of DCA, the steepness of the dose gradient outside and inside the gross tumor volume (GTV) boundary is simply defined by the leaf margin (LM) setting to the target volume edge. The dose fall-off outside the small GTV tends to be excessively precipitous, especially with an MLC of 2.5-mm leaf width, which is predisposed to the insufficient coverage of microscopic brain invasion and other inherent inaccuracies. Meanwhile, insufficient dose increase inside the GTV boundary, i.e., less inhomogeneous GTV dose, likely leads to inferior and less sustainable tumor response. The more inhomogeneous GTV dose is prone to the steeper dose gradient outside the GTV and vice versa. Herein, we describe an alternative simply modified DCA (mDCA) planning that was uniquely devised to optimize the dose gradient outside and inside the GTV boundary for further enhancing and consolidating local control of small BM. For a succinct exemplification, a 10-mm spherical target was assumed as a GTV for DCA planning using a 2.5-mm mMLC. The benchmark plan was generated by adding a 0-mm LM to the GTV edge by assigning a single fraction of 30 Gy to the isocenter, in which the GTV coverage by 24 Gy with 80% isodose surface (IDS) was 96%, i.e., D96%, while the coverage of GTV + isotropic 2 mm volume by 18 Gy with 60% IDS was 70%, with the D98% being 12 Gy with 40% IDS, viz., too steep dose fall-off outside the GTV boundary. Alternatively, the increase of LM with or without decreasing the isocenter dose enables the increase of the GTV + 2 mm coverage by 18 Gy while resulting in an inadequate GTV dose with either a less inhomogeneous dose or an excessive marginal dose. Meanwhile, in the newly devised mDCA planning, every single arc was converted to a double to-and-fro arc with different LM settings under the same spatial arrangement, which enabled GTV + 2 mm volume coverage with 18 Gy while preserving the GTV marginal dose and inhomogeneity similar to those for the benchmark plan. Additionally, the different collimator angle (CA) setting for the to-and-fro arcs led to further trimming of the dose conformity. The limitations of general forward planning with only adjusting the LM for every single arc were demonstrated, which can be a contributing factor for local tumor progression of small BM. Alternatively, the mDCA with each double to-and-fro arc and different LM and CA settings enables optimization of the dose gradient both outside and inside the GTV boundary according to the planners' intent, e.g., moderate dose spillage margin outside the GTV and steep dose increase inside the GTV boundary.
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Affiliation(s)
- Kazuhiro Ohtakara
- Department of Radiation Oncology, Kainan Hospital Aichi Prefectural Welfare Federation of Agricultural Cooperatives, Yatomi, JPN.,Department of Radiology, Aichi Medical University, Nagakute, JPN
| | - Kojiro Suzuki
- Department of Radiology, Aichi Medical University, Nagakute, JPN
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Yan M, Holden L, Wang M, Soliman H, Myrehaug S, Tseng CL, Detsky J, Ruschin M, Tjong M, Atenafu EG, Das S, Lipsman N, Heyn C, Sahgal A, Husain Z. Gamma knife icon based hypofractionated stereotactic radiosurgery (GKI-HSRS) for brain metastases: impact of dose and volume. J Neurooncol 2022; 159:705-712. [PMID: 35999435 DOI: 10.1007/s11060-022-04115-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/09/2022] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases. METHODS Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors. RESULTS Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7 months (range 0.5-47.6). The median total dose and prescription isodose was 27.5 Gy (range, 20-27.5) in 5 daily fractions and 52% (range, 45-93), respectively. The median overall survival (OS) was 12.7 months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5 Gy vs. ≤ 25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5 cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE. CONCLUSION Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE.
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Affiliation(s)
- Michael Yan
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Lori Holden
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Michael Wang
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Hany Soliman
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Sten Myrehaug
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Chia-Lin Tseng
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Jay Detsky
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Mark Ruschin
- Department of Medical Physics, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Michael Tjong
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Eshetu G Atenafu
- Department of Biostatistics, Princess Margaret Cancer Center, University of Toronto, Toronto, Canada
| | - Sunit Das
- Department of Neurosurgery, St. Michael's Hospital, University of Toronto, Toronto, Canada
| | - Nir Lipsman
- Department of Neurosurgery, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Canada
| | - Chinthaka Heyn
- Department of Radiology, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Canada
| | - Arjun Sahgal
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada
| | - Zain Husain
- Department of Radiation Oncology, Odette Cancer Center, University of Toronto, Toronto, Canada. .,Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
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Kanayama N, Ikawa T, Ohira S, Hirata T, Morimoto M, Ogawa K, Teshima T, Konishi K. Volumetric reduction of brain metastases after stereotactic radiotherapy: Prognostic factors and effect on local control. Cancer Med 2022; 11:4806-4815. [PMID: 35535485 PMCID: PMC9761087 DOI: 10.1002/cam4.4809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/11/2022] [Accepted: 04/25/2022] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND AND PURPOSE Few reports include volumetric measurements as endpoints after stereotactic radiotherapy (SRT) despite the importance of such measurements. This study aimed to (1) investigate the impact of the volumetric response (specifically, an over 65% and over 90% volume reduction in brain metastases) at 6 months post-SRT on local control and (2) identify the predictive factors for a volumetric response of over 65% and over 90%. MATERIALS AND METHODS This study included 250 unresected brain metastases (>0.3 cc) treated with SRT. Doses were stratified according to the biological effective dose (BED). The BED was calculated using four models: linear-quadratic (LQ): α/β = 10; LQ: α/β = 20; LQ cubic: α/β = 12; and LQ linear: α/β = 10. The median prescription dose was 30 Gy/3 fractions (BED20, 45). The median follow-up time after SRT was 18.6 months (range, 6.4-81.8 months). RESULTS In the multivariate analysis, over 65% volume reduction and over 90% volume reduction were prognostic factors for local control (hazard ratio: 2.370, p = 0.011 and hazard ratio: 3.161, p = 0.014, respectively). A dose of 80% of the gross tumor volume (GTV) D80 > BED20 58 was a predictive factor for over 65% and over 90% volume reductions (odds ratio: 1.975, p = 0.023; odds ratio: 3.204, p < 0.001, respectively). CONCLUSION Robust volume reduction of brain metastases at 6 months post-SRT can predict local control. GTV D80 in the LQ model: α/β = 20 may be warranted for good volume reduction.
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Affiliation(s)
- Naoyuki Kanayama
- Department of Radiation Oncology, Osaka International Center InstituteOsakaJapan
| | - Toshiki Ikawa
- Department of Radiation Oncology, Osaka International Center InstituteOsakaJapan
| | - Shingo Ohira
- Department of Radiation Oncology, Osaka International Center InstituteOsakaJapan
| | - Takero Hirata
- Department of Radiation OncologyOsaka University Graduate School of MedicineOsakaJapan
| | - Masahiro Morimoto
- Department of Radiation Oncology, Osaka International Center InstituteOsakaJapan
| | - Kazuhiko Ogawa
- Department of Radiation OncologyOsaka University Graduate School of MedicineOsakaJapan
| | | | - Koji Konishi
- Department of Radiation Oncology, Osaka International Center InstituteOsakaJapan
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