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

  • Seung Heon Lee Gachon University Gil Medical Center
  • Kyu Chan Lee Gachon University Gil Medical Center
  • Jinho Choi Gachon University Gil Medical Center
  • So Hyun Ahn Gachon University Gil Medical Center
  • Seok Ho Lee Gachon University Gil Medical Center
  • KiHoon Sung Gachon University Gil Medical Center
  • Se Hee Kil Gachon University Gil Medical Center

Abstract

Purpose

To investigate whether biologically effective dose (BED) based on linear-quadratic model can be used to estimate spinal cord tolerance dose in spine stereotactic body radiation therapy (SBRT) delivered in 4 or more fractions.

Material 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 radiation-induced spinal cord toxicity during follow-up period of 0.5 to 53.9 months.

Conclusion

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.

Author Biographies

Seung Heon Lee, Gachon University Gil Medical Center
Department of Radiation Oncology
Kyu Chan Lee, Gachon University Gil Medical Center

Department of Radiation Oncology

Chair of the Department of Radiation Oncology

Jinho Choi, Gachon University Gil Medical Center
Department of Radiation Oncology
So Hyun Ahn, Gachon University Gil Medical Center
Department of Radiation Oncology
Seok Ho Lee, Gachon University Gil Medical Center
Department of Radiation Oncology
KiHoon Sung, Gachon University Gil Medical Center
Department of Radiation Oncology
Se Hee Kil, Gachon University Gil Medical Center
Gachon Medical Research Institute
Published
2015-04-24
How to Cite
Lee, S. H., Lee, K. C., Choi, J., Ahn, S. H., Lee, S. H., Sung, K., & Kil, S. H. (2015). Clinical applicability of biologically effective dose calculation for spinal cord in fractionated spine stereotactic body radiation therapy. Radiology and Oncology, 49(2). Retrieved from https://radioloncol.com/index.php/ro/article/view/2278
Section
Medical Physics