This document provides an overview and practical tips for spine stereotactic body radiation therapy (SBRT). It discusses patient selection criteria including good performance status and life expectancy. Required imaging includes MRI and CT to aid targeting of the gross tumor volume (GTV) and clinical target volume (CTV). Treatment planning considerations include dose selection of 24-35Gy in 3-5 fractions and organ at risk constraints. Delivery involves cone beam CT guidance to ensure accurate positioning. Case studies demonstrate targeting of spinal metastases from different primary cancers. The document emphasizes the importance of immobilization, image guidance and multidisciplinary care for safe and effective spine SBRT.

1. Education
Clinical Care
Research
Spine SBRT 101 : practical tips
3rd International SBRT symposium
2016
Dr. Bala Vellayappan
Assoc. Consultant
MBBS (Singapore), GDFM,
FRANZCR

2. Outline
• Background and rationale
• Determining eligibility (Patient selection)
• Required imaging
• Simulation
• Targeting
• Planning, dose selection
• OAR tolerances
• Plan evaluation
• Delivery and IGRT
• Case studies

3. Background
• Exponential rise in the use of SBRT
• Patients are living longer due to more effective
systemic therapy, and therefore durable control
becomes important
• There is a dose-response curve in palliation. Higher
doses  more durable pain relief
• SBRT affords high doses in short schedules (win-
win)

4. Rationale
• Advances in techniques, equipment and positional
verification high doses in tight spaces
• 35Gy/ 5# = BED 60Gy
• 24Gy/2# = BED 53Gy
• Large dose fractions = immune-mediated cell-killing
and endothelial apoptosis 1,2
1. Radiobiological mechanisms of stereotactic body radiation therapy and stereotactic radiation surgery.
Kim et al Radiat Oncol J. 2015 Dec; 33,265
2. Radiation-Induced Vascular Damage in Tumors: Implications of Vascular Damage in Ablative
Hypofractionated Radiotherapy. Park et al. Radiation Research: March 2012, (177),311

5. Patient Selection
• Patient factors
• KPS >50 (preferably 70)
• Life expectancy > 6m
• Able to lie still for treatment
• Not radiosensitive histology
like MM or lymphoma
• Patients with previous EBRT
<45Gy (3 months apart)
• Tumour factors
• <=3 contiguous segments
• Not in cord/cauda
compression (ideal >2mm
gap)
• Spine not unstable (SINS
score)

6. Revised Tokuhashi Score SINS score
Category Options
General Condition
(Performance status)
Poor
Moderate
Good
Number of extraspinal
bone met
>=3
1-2
0
Number of mets in
vertebral body
>=3
2
1
Mets to major internal
organs
Unremovable
Removable
No mets
Primary cancer site
Palsy Complete (Frankel
A,B)
Incomplete (Frankel
C,D)
None (Frankel E)
0-8 : 6m
9-11 : 6 – 12m
12-15 >1 y
Ref : Tokuhashi Y, et al. Spine 2005 2186-91
Component Options
Location Junctional
Mobile Spine
Semi-rigid
Rigid
Pain Yes
Occasional pain but not mechanical
Pain-free lesion
Bone Lesion Lytic
Mixed
Blastic
Radiographic spinal
alignment
Subluxation/translation present
De novo deformity
Normal
Vertebral body
collapse
>50%
<50%
No collapse with >50% body
involved
None
Posterolateral
involvement of spinal
elements
Bilateral
Unilateral
None
0-6 : stable
7 – 12: potentially unstable
13 – 18 : unstable
Ref: Fisher et al Spine 2010 1221

7. Denis’ three column concept
• One column injury is stable
• Two column injury is unstable
• Three column injury is
invariably unstable
Spinal instability as defined by the three-column spine concept in acute spinal trauma. Clin Orthop Relat Res. 1984
Oct;(189):65-76.

8. All cord compressions are not equal…
Bilsky et al J Neurosurg: Spine V13 2010

9. MSKCC NOMS algorithm
• NEUROLOGICAL ASSESSMENT
• ONCOLOGICAL ASSESSMENT
• MECHANICAL ASSESSMENT
• SYSTEMIC ASSESSMENT
Laufer et al. The Oncologist 2013; 18 : 744

10. Post-operative cases
• For patients in cord compression, or with unstable spines – upfront
surgical stabilization is preferred
• Challenges with post-operative SBRT
– Uncertainties in targeting due to streak artefacts
– Beam attenuation by rods (uncertainties in dose calculation, beam
modelling)
• Potential solutions
– Speak to your radiologist!
– Artefact reduction protocols are available
– CT myelogram delineates cord well, but may still have streak artefacts

12. Which machine should I use?

13. Is there one machine that is better?
ASTRO 2016

14. VMAT

15. Cyberknife

16. Tomotherapy – fixed jaw

17. Tomotherapy – dynamic jaws

18. You have decided to
deliver SBRT..now
what?

19. Patient preparation
• During consult –
discuss goals and
challenges of the
procedure with the
patient
• Assess pain score,
anxiety and
claustrophobia
• MRI whole spine with
contrast
– T1/T2 sag and axial
– Short tau inversion
recovery (STIR)
• Re-staging CT
• Targeted MRI (limited
sequences for RT
planning)
• +- CT myelogram
Required imaging

20. CT-Simulation
• Near-rigid immobilization
• Thick thermoplastic shell for lesions above T4 (5 point)
• BODYFix for other sites (not simple Vaclock)
• IV contrast optional (good to have)
• We don’t use 4DCT or fiducials
• <3mm cuts through region of interest
• Patient must be relaxed and pain-free *
• Recent MRI for fusion
• Good practice point : reposition patient before simulation

21. Rigid immobilisation
• T-shaped bags – more support
under the arms
• Full length bag - more support
for pelvis and legs

22. Targeting
• GTV (tumour alone) – use diagnostic MRI(T1c,T2) and PET to help
• Involve the surgeon for post—op cases
• CTV = extend GTV to cover adjacent normal looking marrow. (refer to
consensus guidelines)
• Organs at risk (at least 5cm above and below PTV)
 Cord or cauda (Defined on T2-MRI) , well above and below target
 If cord not visible, can delineate thecal sac
 Nerve root/plexus
 Esophagus PRV
 Bowel
 Kidney
 Skin (5mm)

23. Anatomy of the spine

24. RTOG 0631 targeting

25. Consensus
Cox et al Red Journal Vol 83 e597

26. What to include as CTV

27. Treatment planning
• Core group
• Dose selection
– 3 to 5 fraction SBRT is more forgiving, and still gives good results
– 24 – 27Gy in 3 fractions, 30 to 35Gy in 4 to 5 fractions
• Dose constraints
– TG 101
– RTOG 0631
– Follow what the experts do
• VMAT 2 arc
– Quicker than 9-13 field IMRT
– Non-coplanar usually doesn’t add much, and runs the risk of couch
collision
• Plan evaluation
– Know where to compromise
– Cord takes priority  there will be dose spillage outside target

28. Treatment delivery
• Equipment
– Commissioning and QA is very important
– Daily machine and indv. patient QA
• Manage the situation
– Setup, imaging, verification and delivery done swiftly
• Setup with lasers and DRO shift initially
• 3D Cone-beam CT
– Estimated to be 2-5minutes
• Tolerances should align with PTV/PRV margins (Desired 1mm/2degree)
• What to match?
• Treatment time
• Mid-CBCT ? Post CBCT?
• Pre-meds
– Dexamethasone 4mg prior to each fraction and few days after
– Adequate analgesia
– Anxiolytics as needed

29. Case study 1 (Patient 001)
• 70 Male, ECOG 0
• Metastatic Cholangioca since 2006
• Progressive C2 lesion causing neck pain
 1) Review the images
 2) Target the lesion

33. Case study 2 (Patient 003)
• 37 F, ECOG 0
• Met cervical Ca
• On PDL1 clinical trial
• Symptomatic L1 met s/p stabilisation
• For post-op SBRT
 1) Review the images
 2) Target the lesion
*Post-op targeting is more subjective. Post-op consensus guidelines likely to
be out in Red Journal soon

38. Case study 3 (Patient 009)
• 44, Female, ECOG 1
• RCC diagnosed 2007. Metastatic recurrence in 2012
• Prior RT to prevascular LN 50Gy/20# (2012)
• Started on Pazopanib, then everolimus
• Recent MRI spine shows met involving T3 and L1 vertebral body, with
involvement of superior endplate (L1)
 1) Review the images
 2) Target the lesion

40. T3 lesion

41. L1 lesion

43. Education
Clinical Care
Research
Thank you for your attention!
Email :
bala_vellayappan@nuhs.edu.sg