title: Timely stereotactic body radiotherapy (SBRT) for spine metastases using a rapidly deployable automated planning algorithm.
abstract: OBJECTIVE
  The complex planning and quality assurance required for spine SBRT are a barrier to implementation in time-sensitive or limited resource clinical situations. We developed and validated an automated inverse planning algorithm designed to streamline planning and allow rapid delivery of conformal single fraction spine SBRT using widely available technology.
  
  
  METHODS
  The Rapid Spine (RaSp) automated script successfully generated single fraction SBRT plans for fourteen complex spinal lesions previously treated at a single high-volume institution. Automated RaSp plans were limited to 5 beams with a total of 15 segments (allowing calculation-based verification) and optimized based on RTOG 0631 objectives. Standard single fraction (16 Gy) stereotactic IMRT plans were generated for the same set of complex spinal lesions and used for comparison. A conservative 2 mm posterior isocenter shift was used to simulate minor set-up error.
  
  
  RESULTS
  Automated plans were generated in under 5 min from target definition and had a mean dose to the PTV of 1663 cGy (SD 131.5), a dose to 90 % of PTV (D90) of 1358 cGy (SD 111.0), and a maximum point dose (Dmax) to the PTV of 2055 cGy (SD 195.2) on average. IMRT plans took longer to generate but yielded more favorable dose escalation with a mean dose to the PTV of 1891 cGy (SD 117.6), D90 of 1731 cGy (SD 126.5), and Dmax of 2218 cGy (SD 195.7). A 2 mm posterior shift resulted in a 20 % (SD 10.5 %) increase in cord dose for IMRT plans and a 10 % (SD 5.3 %) increase for RaSp plans. The 2 mm perturbation caused 3 cord dose violations for the IMRT plans and 1 violation for corresponding RaSp plans.
  
  
  CONCLUSIONS
  The Rapid Spine plan method yields timely and dosimetrically reasonable SBRT plans which meet RTOG 0631 objectives and are suitable for rapid yet robust pretreatment quality assurance followed by expedited treatment delivery. RaSp plans reduce the tradeoff between rapid treatment and optimal dosimetry in urgent cases and limited resource situations.
authors: Department of Radiation Oncology, Cleveland Clinic, Taussig Cancer Institute, Cleveland, OH USA.
authors: Omar Y
authors: OY
authors: Mian
authors: Delmarva Radiation Services, Tunnell Cancer Center, Rehoboth Beach, DE USA.
authors: Owen
authors: O
authors: Thomas
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Joy J Y
authors: JJ
authors: Lee
authors: Department of Radiation Oncology, Indiana University, Indianapolis, IN USA.
authors: Yi
authors: Y
authors: Le
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Todd
authors: T
authors: McNutt
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Michael
authors: M
authors: Lim
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Daniele
authors: D
authors: Rigamonti
authors: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Jean-Paul
authors: JP
authors: Wolinsky
authors: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Daniel M
authors: DM
authors: Sciubba
authors: Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Ziya L
authors: ZL
authors: Gokaslan
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Kristin
authors: K
authors: Redmond
authors: Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors: Lawrence
authors: L
authors: Kleinberg
keywords: Automated planning; Radiation therapy; SBRT; Spinal lesions