Work

Efficient Monte Carlo modeling for Gamma Knife Perfexion

Year: 2026

Type: article

Abstract: Monte Carlo (MC) simulations constitute the most accurate tool for dosimetric analysis in small radiation fields, such as those generated by the Leksell Gamma Knife Perfexion (LGK-PFX) system. However, implementing a fully detailed model of the system is computationally demanding, both in terms of processing time and geometric complexity, due to the explicit inclusion of the 576 collimators distributed throughout the device. To address this limitation, we present an efficient and accurate model based on a single phase-space file (PSF) generated from a source-collimator simulation for each collimator size (4, 8, and 16 mm), computed using PenEasy Monte. The resulting PSF is subsequently rotated to the required orientations to reproduce the system response. This approach drastically reduces the effective computational burden, as each reference PSF is generated only once and can then be reused to simulate any desired LGK-PFX configuration. Compared with full-system models that require hundreds of hours of computation and storage on the order of terabytes, the proposed rotating-PSF strategy enables Monte Carlo simulations with moderate computational resources, making MC-based verification feasible in a clinical context. The model was validated by comparing MC-generated dose distributions with measurements performed using EBT4 radiochromic films at Ruber International Hospital (Madrid), as well as with data provided by Elekta and other MC-based studies. A 7%-0.5 mm gamma analysis of the dose profiles showed pass rates above 95%. Output factors (OFs) for the 4 mm and 8 mm collimators were 0.848 ± 0.011 and 0.889 ± 0.011, respectively, in a cubic water phantom. Overall, the rotating PSF approach preserves dosimetric accuracy while substantially improving computational efficiency, providing a practical and clinically relevant solution for dosimetry with the LGK-PFX system.

Source: Applied Radiation and Isotopes

DOI: 10.1016/j.apradiso.2026.112686

Authors: Díaz Nataly, Gutiérrez Jorge, Martínez Julio, Udías José Manuel, Ibáñez Paula

Institutions: Universidad Complutense de Madrid, Hospital Ruber Internacional, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos

Language: English

Topic: Advanced Radiotherapy Techniques

Subfield: Radiation

Field: Physics and Astronomy

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,220