Spinal Cord Tolerance for Stereotactic Body Radiotherapy

Journal Article · Tue Jun 01 04:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.05.023· OSTI ID:21372307

Sahgal, Arjun ^[1]; Lijun, Ma ^[2]; Gibbs, Iris ^[3]; Gerszten, Peter C ^[4]; Ryu, Sam ^[5]; Soltys, Scott ^[3]; Weinberg, Vivian ^[6]; Shun, Wong ^[7]; Chang, Eric ^[8]; Fowler, Jack ^[9]; Larson, David A ^[2]

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1. Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Princess Margaret Hospital, University of Toronto, Toronto, Ontario (Canada)
2. Department of Radiation Oncology, University of California San Francisco, San Francisco, California (United States)
3. Department of Radiation Oncology, Stanford University, Stanford, California (United States)
4. Departments of Neurological Surgery and Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (United States)
5. Department of Radiation Oncology, Henry Ford Hospital, Detroit, Michigan (United States)
6. University of California San Francisco Helen Diller Family Comprehensive Cancer Center Biostatistics Core, San Francisco, California (United States)
7. Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada)
8. Department of Radiation Oncology, M.D. Anderson Cancer Center, University of Texas, Houston, Texas (United States)
9. Departments of Human Oncology and Medical Physics, University of Wisconsin, Madison, Wisconsin (United States)

Purpose: Dosimetric data are reported for five cases of radiation-induced myelopathy after stereotactic body radiotherapy (SBRT) to spinal tumors. Analysis per the biologically effective dose (BED) model was performed. Methods and Materials: Five patients with radiation myelopathy were compared to a subset of 19 patients with no radiation myelopathy post-SBRT. In all patients, the thecal sac was contoured to represent the spinal cord, and doses to the maximum point, 0.1-, 1-, 2-, and 5-cc volumes, were analyzed. The mean normalized 2-Gy-equivalent BEDs (nBEDs), calculated using an alpha/beta value of 2 for late toxicity with units Gy 2/2, were compared using the t test and analysis of variance test. Results: Radiation myelopathy was observed at the maximum point with doses of 25.6 Gy in two fractions, 30.9 Gy in three fractions, and 14.8, 13.1, and 10.6 Gy in one fraction. Overall, there was a significant interaction between patient subsets and volume based on the nBED (p = 0.0003). Given individual volumes, a significant difference was observed for the mean maximum point nBED (p = 0.01). Conclusions: The maximum point dose should be respected for spine SBRT. For single-fraction SBRT 10 Gy to a maximum point is safe, and up to five fractions an nBED of 30 to 35 Gy 2/2 to the thecal sac also poses a low risk of radiation myelopathy.

• OSTI ID: 21372307
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 77; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CENTRAL NERVOUS SYSTEM
DISEASES
DOSES
FRACTIONATED IRRADIATION
INJURIES
IRRADIATION
MEDICINE
NEOPLASMS
NERVOUS SYSTEM
NUCLEAR MEDICINE
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
RADIOLOGY
RADIOTHERAPY
SPINAL CORD
THERAPY