A prospective study evaluating prone and supine positioning for radiation planning of spine Cyberknife radiotherapy treatment. Patients with tumours in which PTV coverage is compromised due to tumour geography, including posteriorly based lesions in the vertebral column and close proximity to organ at risk (other than the spinal cord).

This is a prospective, non-randomised radiotherapy planning study.

Subsets of patients with specific tumour and anatomical characteristics will benefit from improved PTV prescription isodose coverage, reduced spinal cord dose, and organs at risk dose by undergoing either prone or supine setup, planning and treatment. Both prone and supine CT radiotherapy planning scans for patients undergoing spine SBRT treatment will undergo comparison of radiotherapy plans to guide recommendation of prone treatment for future patients.

Patients continue to receive treatment in the proposed position as recommended y their treating physician.

Inclusion Criteria:

• • Patients undergoing Cyberknife treatment to spinal metastasis

  • >18 years of age
  • Thoracic, lumbar and sacral spinal metastasis
  • Patients suitable to undergo radiotherapy planning CT scans in the prone position (treating physician assessed as having spinal stability).
  • All solid tumour types will be eligible

Exclusion Criteria:

• • Primary spinal tumours

  • Vertebral disease resulting in unstable spinal vertebrae
  • Cervical tumours (patients will be unable to have a thermoplastic shell made for the prone position).
  • Patients with significant pain on prone lying (to be assessed by physician prior to consent)
  • Bilsky epidural score of 2 or greater (see appendix 1)
  • Pre-existing musculoskeletal chronic back medical diagnoses that would preclude CT scanning in the prone position.