Single-Fraction SBRT vs. Fractionated 3DCRT for Spinal Metastases

CT simulation was carried out with custom immobilization using Aquaplast® head masks, vacuum mattresses, and/or Wingstep® arm abduction framework. OARs (including the spinal cord) and the clinical target volume (CTV) were delineated on the planning CT with MRI co-registration. The planning target volume (PTV) was to be covered by the 80% isodose, and 24 Gy in a single fraction was prescribed to this isodose line. OAR tolerance doses were per the RTOG 0631 trial [13 (link)]. SBRT techniques included helical Tomotherapy, step-and-shoot intensity-modulated radiotherapy, or volumetric-modulated arc therapy. Treatment was delivered by an Elekta Versa HD accelerator. Image guidance was performed in all patients by means of megavoltage CT and/or TomoTherapy platforms.
For the 3DCRT arm, treatment was performed as irradiation of the involved vertebral body as well those immediately above and below to a total dose of 30 Gy in 10 fractions, most commonly delivered with 3/4 anteroposterior/posteroanterior beams. Position verification was carried out weekly before radiotherapy by kilovoltage cone-beam CT (kV-CBCT) and before each fraction by orthogonal portal images being compared with digitally reconstructed radiographs (DRR) from the planning CT.