A dosimetric comparative analysis of Brainlab elements and Eclipse RapidArc for spine SBRT treatment planning

Abstract

Purpose: This is a dosimetric study comparing stereotactic body radiotherapy (SBRT) plans of spine tumors using Brainlab Elements Spine planning module against Eclipse RapidArc plans. Dose conformity, dose gradient, dose fall-off, and patient-specific quality assurance (QA) metrics were evaluated. Methods: Twenty patients were immobilized in supine position using half Vac‐Lok. A prescription dose of 16 Gy in a single fraction was planned for Varian TrueBeam. Conformal arc plans were generated with Pencil beam (PB), MonteCarlo (MC) in Elements, and RapidArc with Acuros XB algorithm in Eclipse using identical treatment geometry. Results: Eclipse, Elements PB, and Elements MC generated dosimetrically conformal plans having Inverse Paddick Conformity Index (IPCI) <1.3. All plans satisfied the dose constraints to target and OARs. Elements PB had a sharper gradient than Elements MC with average GI of 3.67(95% CI: 3.52-3.82) and 4.06 (95% CI: 3.93-4.20) respectively. Eclipse plans were more homogeneous with mean HI= 1.22 (95% CI: 1.20-1.23) that is lower than others. Average maximum clinical target volume (CTV) doses were higher in Elements MC with 22.31Gy (95% CI: 21.87-22.74), while PB plans have 21.15Gy (95% CI: 20.36-21.96), respectively. Elements MC and PB plans had lower average dose to 0.35 cc of spinal cord (D0.35cc) of 7.60Gy (95% CI: 7.18-8.02) and 8.42Gy (95% CI: 7.83-9.01). All plans had >95% points passing the gamma QA criteria at 3%/2 mm. Conclusion: All treatment plans achieved clinically acceptable target coverage >95% and meet spinal cord dose limits. Smart optimization in Brainlab Elements spine module produced dosimetrically superior plans by better spinal cord sparing.

Evaluation of a dedicated software for semi-automated VMAT planning of spine Stereotactic Body Radiotherapy (SBRT)

“…The authors also noted an improvement of PCI and GI when using Elements Spine SRS, with the same beam geometry in both TPS but with duplication option in Spine SRS. In another study, the same TPS were compared, but using different algorithms for final dose calculation (AcurosXB for Eclipse TPS; Pencil Beam and MC algorithms for Spine SRS) [7]. Similar to us, they found a significant difference on spinal cord sparing, and on the maximum dose to the CTV with on average a maximum dose 1.6 Gy higher in Spine SRS using MC algorithm.…”

“…Several studies have compared E-SRS with other VMAT solutions [6], [7], [8], [9]. In a first study, similar dosimetric results were found on the dose to the spinal cord and to the PTV, when comparing the E-SRS with Eclipse TPS (AAA algorithm) [6].…”

“…Simultaneously, specialized planning solutions are also elaborated. The Elements TPS (Brainlab, Munich) has been developed according to this philosophy, with specific modules dedicated to stereotactic radiosurgery (SRS): Cranial SRS, Multiple Brain Mets SRS or Spine SRS [6], [7]. Elements Spine SRS (E-SRS) allows an automated VMAT planning process, based on the use of templates defining beam geometry and dosimetric objectives on organs at risk (OAR) and target volumes.…”

“…The dosimetric performances of E-SRS TPS compared with other clinical TPS were evaluated in 4 different studies [6], [7], [8], [9]. In two recent studies, the dosimetric superiority of Elements Spine SRS compared with Eclipse TPS (Varian Medical Systems, Palo Alto, USA), in terms of spinal cord sparing [6], [7] and gradient index [9] was observed. In another study comparing the same TPS, Piliero et al [8] concluded to a similar plan quality between both TPS.…”

Commissioning and validation of a Monte Carlo algorithm for spine stereotactic radiosurgery

“…To circumvent the planning optimization difficulty for SBRT spine treatment, Brainlab (Munich, Germany) created a dedicated spine optimization algorithm, that is, built into their Elements Spine SRS v3.0 treatment planning system. The algorithm is tailored for the concave geometry of SBRT spine and has been shown to produce plans with improved conformity and gradient indices while reducing spinal cord dose 12–17 …”