Dosimetric Comparison of Functional Radiosurgery Treatments for Trigeminal Neuralgia, Essential Tremor, and Obsessive-compulsive Disorder Using Gamma Knife, CyberKnife, and Linear Accelerators
Carlos Daniel Venencia, Crystian Wilian Chagas Saraiva, Gabriela Reis dos Santos de JesusAbstract
Purpose:
This study aims to evaluate and compare dose distribution for a trigeminal neuralgia (TN), essential tremor (ET), and obsessive-compulsive disorder (OCD) plan, using Gamma Knife (GK) Perfexion, CyberKnife (CK), and linear accelerators (linac) for a single treatment case.
Materials and Methods:
For all treatment platforms, plans utilized the same isocenter position and anatomical structures, with GK Perfexion plans as the reference. The prescribed doses were established at 90 Gy for TN, 140 Gy for ET, and 120 Gy for OCD. The irradiation geometry for each platform was defined to optimize the dose gradient vector in all directions. Dose distributions were evaluated both qualitatively and quantitatively. Dose profiles were extracted from axial and coronal plans to assess and compare the full width at half maximum (FWHM) and the penumbra size. Doses to normal tissue were compared, and the gradient index (GI) was used to evaluate the dose fall-off.
Results:
Dose distribution from CK and linac closely imitated GK Perfexion. The maximum difference for FWHM and penumbra was 2.1 mm and 1.3 mm, respectively, for the TN plans, with linac producing steeper dose gradients than GK Perfexion. The GI, in turn, was significantly different for the CK ET plan, with a value of 5.4 compared to 3.8 for GK Perfexion and linac. This difference did not have a clinical impact, as the dose to normal tissue was within tolerance.
Conclusions:
All platforms provided appropriate dose distribution and dose constraints.