ABSTRACT
Radiation-induced myelopathy is one of the most feared complications associated with SBRT given that patients can be rendered permanently paralyzed and fatal if it occurs within the cervical spinal cord (Sahgal et al., 2012, 2013; Wong et al., 2015). Speci‚c to SBRT, the issue of spinal cord tolerance was of paramount signi‚cance as there was little experience in exposing the spinal cord to short-course high-dose-per-fraction radiation. Furthermore, radiobiology would support greater sensitivity to normal tissue late e‰ects as the dose per fraction increases. Early adopters either believed that the spinal cord tolerance was no greater than what would be traditionally expected and applied conservative limits to small volumes, such as the point maximum, of spinal cord. However, others believed in selective volume-based dose escalation, allowing higher than expected point maximum cord doses arguing that the point maximum volume is clinically insigni‚cant as long as larger volumes such as 0.1 or 1 cc volumes are exposed to subthreshold doses.
