A dosimetric study comparing Cyberknife and LINAC-based stereotactic radiotherapy or radiosurgery treatments

Abstract

BackgroundWhile Gamma Knife and CyberKnife are commonly used for Stereotactic radiosurgery (SRS), their availability is limited. In contrast, linac-based SRS using linear accelerators (linacs) is more accessible and widely used. PurposeOur study aims to evaluate Linac-based SRS with the Varian RapidArc technique for treating brain metastases. The primary objective is to compare the quality of treatment plans between RapidArc and CyberKnife modalities. Materials & methodsTen patients with a single brain metastasis were treated using the CyberKnife machine with prescribed doses ranging from 18 to 25 Gy. Treatment plans utilized Multiplan software for CyberKnife and Eclipse for RapidArc plans. The plans were evaluated based on dose metrics for the target and critical structures, treatment time, and brain tissue volume. ResultsBoth techniques provided acceptable Gross tumor volume coverage and organs at risk sparing. CyberKnife delivered a higher integral dose to the Gross tumor volume and brain tissues compared to RapidArc (p < 0.05). The conformity index was slightly better in RapidArc (1.14 ± 0.25) compared to CyberKnife (1.22 ± 0.12), but the difference was not statistically significant (p > 0.05). However, CyberKnife exhibited a better dose gradient index (4.52 ± 0.99) compared to RapidArc (8.6 ± 7.28). The treatment time in RapidArc was significantly lower compared to CyberKnife, p < 0.05. RapidArc demonstrated lower minimum and maximum doses to some organs at risk, although some differences were not statistically significant. For normal brain tissues, V12Gy was significantly lower with RapidArc (3.27 ± 2.92) compared to CyberKnife (4.09 cc ± 3.27). ConclusionThe RapidArc technique is capable of achieving similar treatment quality as CyberKnife systems for SRS treatments. It offers improved target coverage, higher conformity, and homogeneous dose distribution within the Planning target volume if homogeneity is desirable in some intuitions or cases. In addition, it can also achieve low integral doses to organs at risk and brain tissues.