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

Abstract

Background This study evaluates the feasibility of HyperArc (HA) for trigeminal neuralgia (TN) by comparing dose distribution with CyberKnife (CK). Methods Contour sets from twenty patients who had undergone CK for TN were used to generate HA treatment plans for comparison. Two different TN target delineation settings were used: the whole segment of the trigeminal nerve root entry zone (REZ) group and the 5-mm spherical target group. The prescribed dose was 65 Gy in a single fraction, prescribed to the 80% isodose line. The CK and HA treatment plans were compared for target coverage, sparing of organs at risk (OARs), and dose distribution metrics. Results In the whole segment of the REZ group, the HA plans showed statistically significant differences with higher target coverage than the CK plans. The mean brain doses for HA and CK were 0.83 Gy and 1.15 Gy, respectively (P < 0.001). The brain V12 was significantly smaller for HA plans (5.9 cm3) than CK plans (6.9 cm3). Significant achievement in the doses of the ipsilateral/contralateral cranial nerve (CN) VII/VIII were observed in the HA plans than the CK plans. The conformity index was significantly greater in the HA plans compared to the CK plans. The dose gradient radius was similar for the CK and HA plans. In the 5mm-spherical target group, both plans showed good target coverage, with the CK plans exhibiting better brain sparing and higher CN VII/VIII dose. The dose distribution metrics were similar for both plans. Conclusions The HA technique is a feasible alternative for TN treatment, offering excellent organ-at-risk sparing and favorable dosimetric distribution.