<abstract xmlns="http://www.w3.org/1999/xhtml"> Background. The aim of the study was to investigate whether biologically effective dose (BED) based on linearquadratic model can be used to estimate spinal cord tolerance dose in spine stereotactic body radiation therapy (SBRT) delivered in 4 or more fractions. Patients and methods. Sixty-three metastatic spinal lesions in 47 patients were retrospectively evaluated. The most frequently prescribed dose was 36 Gy in 4 fractions. In planning, we tried to limit the maximum dose to the spinal cord or cauda equina less than 50% of prescription or 45 Gy2/2. BED was calculated using maximum point dose of spinal cord. Results. Maximum spinal cord dose per fraction ranged from 2.6 to 6.0 Gy (median 4.3 Gy). Except 4 patients with 52.7, 56.4, 62.4, and 67.9 Gy2/2, equivalent total dose in 2-Gy fraction of the patients was not more than 50 Gy2/2 (12.1- 67.9, median 32.0). The ratio of maximum spinal cord dose to prescription dose increased up to 82.2% of prescription dose as epidural spinal cord compression grade increased. No patient developed grade 2 or higher radiationinduced spinal cord toxicity during follow-up period of 0.5 to 53.9 months. Conclusions. In fractionated spine SBRT, BED can be used to estimate spinal cord tolerance dose, provided that the dose per fraction to the spinal cord is moderate, e.g. &lt; 6.0 Gy. It appears that a maximum dose of up to 45-50 Gy2/2 to the spinal cord is tolerable in 4 or more fractionation regimen.</abstract>

Background. The aim of the study was to investigate whether biologically effective dose (BED) based on linearquadratic model can be used to estimate spinal cord tolerance dose in spine stereotactic body radiation therapy (SBRT) delivered in 4 or more fractions. Patients and methods. Sixty-three metastatic spinal lesions in 47 patients were retrospectively evaluated. The most frequently prescribed dose was 36 Gy in 4 fractions. In planning, we tried to limit the maximum dose to the spinal cord or cauda equina less than 50% of prescription or 45 Gy2/2. BED was calculated using maximum point dose of spinal cord. Results. Maximum spinal cord dose per fraction ranged from 2.6 to 6.0 Gy (median 4.3 Gy). Except 4 patients with 52.7, 56.4, 62.4, and 67.9 Gy2/2, equivalent total dose in 2-Gy fraction of the patients was not more than 50 Gy2/2 (12.1- 67.9, median 32.0). The ratio of maximum spinal cord dose to prescription dose increased up to 82.2% of prescription dose as epidural spinal cord compression grade increased. No patient developed grade 2 or higher radiationinduced spinal cord toxicity during follow-up period of 0.5 to 53.9 months. Conclusions. In fractionated spine SBRT, BED can be used to estimate spinal cord tolerance dose, provided that the dose per fraction to the spinal cord is moderate, e.g. < 6.0 Gy. It appears that a maximum dose of up to 45-50 Gy2/2 to the spinal cord is tolerable in 4 or more fractionation regimen.

Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy

Department of Radiation Oncology, Republic of Korea

Gachon Medical Research Institute, Gachon University Gil Medical Center, Republic of Korea

Radiology and Oncology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Background. The aim of the study was to investigate whether biologically effective dose (BED) based on linearquadratic model can be used to estimate spinal...

Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy

Published Online: Mar 25, 2015

Page range: 185 - 191

Received: Nov 07, 2014

Accepted: Jan 05, 2015

DOI: https://doi.org/10.1515/raon-2015-0008

Keywords
biologically effective dose, spine stereotactic body radiation therapy, spinal cord, tolerance dose, linear quadratic model

© by Seung Heon Lee

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy

Published Online: Mar 25, 2015

Page range: 185 - 191

Received: Nov 07, 2014

Accepted: Jan 05, 2015

DOI: https://doi.org/10.1515/raon-2015-0008

Keywordsbiologically effective dose, spine stereotactic body radiation therapy, spinal cord, tolerance dose, linear quadratic model

© by Seung Heon Lee

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
biologically effective dose, spine stereotactic body radiation therapy, spinal cord, tolerance dose, linear quadratic model