The new SRS/FSRT technique HyperArc for benign brain lesions: a dosimetric analysis

Abstract

To evaluate the potential benefit of HyperArc (HA) fractionated stereotactic radiotherapy (FSRT) for the benign brain lesion. Sixteen patients with a single deep-seated, centrally located benign brain lesion treated by CyberKnife (CK, G4 cone-based model) were enrolled. Treatment plans for HA with two different optimization algorithms (SRS NTO and ALDO) and coplanar RapidArc (RA) were generated for each patient to meet the corresponding treatment plan criteria. These four FSRT treatment plans were divided into two groups—the homogeneous delivery group (HA-SRS NTO and coplanar RA) and the inhomogeneous delivery group (HA-ALDO and cone-based CK)—to compare for dosimetric outcomes. For homogeneous delivery, the brain V5, V12, and V24 and the mean brainstem dose were significantly lower with the HA-SRS NTO plans than with the coplanar RA plans. The conformity index, high and intermediate dose spillage, and gradient radius were significantly better with the HA-SRS NTO plans than with the coplanar RA plans. For inhomogeneous delivery, the HA-ALDO exhibited superior PTV coverage levels to the cone-based CK plans. Almost all the doses delivered to organs at risk and dose distribution metrics were significantly better with the HA-ALDO plans than with the cone-based CK plans. Good dosimetric distribution makes HA an attractive FSRT technique for the treatment of benign brain lesions.

Dosimetric Comparison between CyberKnife and HyperArc Treatment Plans for Trigeminal Neuralgia: Cone-Based Robotic System versus High- Definition MLC-Based Linac System

“…Overall, HA demonstrated e cient delivery, rapid dose falloff, and high-quality treatment plans with coplanar and up to 3 noncoplanar arcs. Additionally, the automated HA treatment plan delivery in the SRS work ow increased physicians' con dence in managing small target lesions [12].…”

“…HyperArc (HA, Varian Medical System Inc., Palo Alto, CA, USA) is a novel isocentric-volumetric modulated arc radiotherapy (VMAT) technique explicitly developed for noncoplanar MLC-based stereotactic radiotherapy with automated optimization and delivery [10,11]. Good dosimetric distribution has made HA an attractive SRS technique for treating benign brain lesions [12]. This study aims to evaluate the feasibility of HA for TN by comparing it with the dose distribution of CyberKnife.…”

Single isocenter HyperArc treatment of multiple intracranial metastases: Targeting accuracy

“…Calvo et al 6,7 . showed that dosimetrically comparable plans could be created regardless of whether the isocenter was in the target.…”

“…The introduction of HyperArc (HA) (Varian Medical System, Palo Alto, CA), an automated noncoplanar volumetric modulated arc therapy (VMAT) approach, has generated widespread discussion in the literature 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 on the topic of single‐isocenter stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) of multiple brain metastases. Treatments conducted with a single isocenter have the obvious advantage of reducing treatment time.…”

“…Calvo et al. 6 , 7 showed that dosimetrically comparable plans could be created regardless of whether the isocenter was in the target. When an IMRS plan with a single‐isocenter is designed, off‐isocenter targets within 6 cm of the linac isocenter can be targeted within 1 mm.…”