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Table 4 Target and organs-at-risk definition

From: Clinical practice of image-guided spine radiosurgery - results from an international research consortium

  UHW UPMC UofT UVAMC RSMC
Imaging modality, which is used for GTV definition MRI and CT MRI and CT, FDG-PET if available MRI and CT CT and MRI CT, MRI and FDG-PET
Use of an anatomical target volume concept Anatomical two dose-level target volume concept Anatomical target volume concept Anatomical target volume concept Anatomical target volume concept Anatomical target volume concept
GTV to PTV safety margin 3 mm 2 mm; 3 mm in the sacrum. 2 mm 2 mm None
Protocol if PTV overlaps with the. spinal cord Two dose-level approach;
The OAR spinal cord is always in the PTV-elective and is always excluded from the higher dose PTV-macroscopic
PTV within 1 mm to the spinal cord is excluded from the PTV PTV is limited by the cord or thecal sac for cauda equina If this occurs, we either operate to resect part of the tumor or fractionate the radiation. GTV drawn to edge of OAR
Treatment of the vertebra superior and inferior to the metastatic vertebra No No No No No
Imaging modality for definition of the spinal cord Spinal cord in MRI Spinal cord in MRI Spinal cord in MRI Spinal cord in MRI Spinal canal in CT
Delineation of the spinal cord in cranio-caudal direction At least 1 level above and below PTV 1 level above and below PTV At least 1 level above and below PTV 1 level above and below PTV 1 level above and below PTV
Safety margins around the spinal cord in axial directions 1 mm 1 mm 1.5 mm No 2 mm anterior and 1 mm lateral
Delineation of the cauda equina Thecal sac Thecal sac Thecal sac Thecal sac Thecal sac
Delineation other OARs (e.g. kidney) No application of safety margins No application of safety margins No application of safety margins No application of safety margins No application of safety margins