Technical Note Technique for stereotactic body radiotherapy for spinal metastases Matthew Foote a , Daniel Letourneau a , Derek Hyde b , Eric Massicotte c , Raja Rampersaud d , Michael Fehlings c , Charles Fisher e , Stephen Lewis d , Nancy La Macchia a , Eugene Yu f , Normand J. Laperriere a , Arjun Sahgal a,b,⇑ a Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada b Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada c Division of Neurosurgery and Spinal Program, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada d Department of Orthopedics and Spinal Program, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada e Department of Orthopedics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada f Department of Radiology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada article info Article history: Received 24 February 2010 Accepted 8 April 2010 Keywords: Metastases Radiosurgery Stereotactic body radiotherapy abstract Stereotactic body radiotherapy (SBRT) is an emerging technique for spinal tumours that is a natural suc- cession to brain radiosurgery. The spine is an ideal site for SBRT due to its relative immobility and the potential clinical benefits of high dose delivery, particularly to optimise local control and avoid disease progression that can result in spinal cord compression. However, the proximity of the tumour to the spinal cord, with the potential for radiation myelopathy if the dose is delivered inaccurately or if the spinal cord dose limit is set too high, demands technical accuracy with radiation myelopathy a feared complication. Spine SBRT has been delivered with either a robotic-based linac system such as the Cyber- knife, or with linac-based systems equipped with a multileaf collimator and image guidance system. Regardless of the technology, spine SBRT demands sophisticated treatment planning and delivery. This case-based technical review outlines the SBRT apparatus, planning and treatment delivery in use at the University of Toronto, Toronto, Canada. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Stereotactic body radiotherapy (SBRT) is an emerging technol- ogy in the multidisciplinary management of benign and malignant spinal and paraspinal tumours. 1–3 SBRT refers to high dose per fraction radiotherapy delivered conformally to a target while spar- ing the organs at risk in a single or up to five fractions. 3 Spinal SBRT for metastases aims to improve on existing rates of clinical re- sponse (such as pain relief), tumour control, and to reduce re-treat- ment rates by delivering high, biologically effective, doses per fraction. 3–5 Tumour doses typically range from 16 to 24 Gy in a sin- gle fraction or 24–35 Gy in 3–5 fractions, 1,3,9 which are signifi- cantly greater than current palliative radiation oncology practice. Spine SBRT for spinal metastases is efficacious in the re-treat- ment setting 1,3 and up-front in patients with no prior radia- tion. 1,3–5 However, the literature is limited to retrospective reviews and a few Phase 1/2 clinical studies. 3 There is emerging evidence that this technique may be particularly useful in selected patients with tumours considered resistant to conventional frac- tionation, such as renal cell carcinoma (RCC). 10,11 This case-based technical review outlines the University of Toronto approach to treating spinal tumours with SBRT, and details our immobilisation, treatment planning, and treatment delivery protocols. 2. Case illustration A 68-year-old man investigated for back pain was found to have a locally advanced left-sided renal mass and a destructive meta- static tumour in the 12th thoracic (T12) vertebral body. There was no neurological deficit. The pre-treatment MRI of the T12 mass is demonstrated in Fig. 1A, and shows a lobulated expansile mass involving the posterior half of the right aspect of the T12 vertebral body with extension into the ipsilateral transverse process, facet, and lamina. There is resulting encroachment upon the right T11/ 12 and T12/L1 neural-foramen with significant right lateral epidu- ral tumour causing moderate mass effect and displacement of the spinal cord and thecal sac. Laparoscopic removal of the left kidney revealed a RCC and systemic staging, including positron emission tomography (PET) scan, confirmed the T12 lesion as the only site of metastatic disease. The treatment aim for this patient with oligometastatic disease was potentially curative. Therefore, aggressive local treatments were discussed in a multidisciplinary fashion with dedicated spine 0967-5868/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jocn.2010.04.033 ⇑ Corresponding author. Tel.: +1 416 946 2131; fax: +1 416 480 6002. E-mail address: arjun.sahgal@rmp.uhn.on.ca (A. Sahgal). Journal of Clinical Neuroscience 18 (2011) 276–279 Contents lists available at ScienceDirect Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn