Dr
Francesco Romano
(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy)
The Monte Carlo code Geant4 has been used to simulate the Leksell Gamma Knife® and to verify its treatment planning system Leksell GammaPlan® (LGP). By means of this radiosurgical technique, intracranial lesions can be treated in a single session with high precision and critical brain structures can be protected. Radiation from 201 60Co sources comes through a collimation system to the target area, focusing on the isocenter, where the maximum dose amount is released. Simulations were employed to calculate the dose distribution in a spherical water phantom, the same we used for the validation measurements. In order to simplify the code, we simulated just one single source, rotating the phantom at 201 angular positions, the same of the sources in the device. We validated the simulation by measuring the dose distribution with radiochromic films HS, for all the available collimators (4, 8, 14, 18 mm). Good agreement has been found between experimental data and results of Monte Carlo simulations. Then we used the simulation to verify the dose calculated by LGP. Comparisons between Geant4 and LGP outputs in one and two dimensions were performed at different planes (axial, coronal and sagittal) and depths. The outcomes show that LGP calculates correctly the dose distribution in a homogeneous phantom. Different results were found when different density materials are also included, because LGP assumes the phantom only composed by water. Moreover a complete clinical treatment with a multi-shots configuration has also been simulated and also in this case the results were compared with LGP. Some methods for the optimization of the code and the reduction of calculation time are in progress, in order to possibly propose the application as an advanced example of the Geant4 toolkit.
Summary
The Monte Carlo code Geant4 has been used to simulate the Leksell Gamma Knife® and to verify its treatment planning system Leksell GammaPlan® (LGP). By means of this radiosurgical technique, intracranial lesions can be treated in a single session with high precision and critical brain structures can be protected. Radiation from 201 60Co sources comes through a collimation system to the target area, focusing on the isocenter, where the maximum dose amount is released. Simulations were employed to calculate the dose distribution in a spherical water phantom, the same we used for the validation measurements. In order to simplify the code, we simulated just one single source, rotating the phantom at 201 angular positions, the same of the sources in the device. We validated the simulation by measuring the dose distribution with radiochromic films HS, for all the available collimators (4, 8, 14, 18 mm). Good agreement has been found between experimental data and results of Monte Carlo simulations. Then we used the simulation to verify the dose calculated by LGP. Comparisons between Geant4 and LGP outputs in one and two dimensions were performed at different planes (axial, coronal and sagittal) and depths. The outcomes show that LGP calculates correctly the dose distribution in a homogeneous phantom. Different results were found when different density materials are also included, because LGP assumes the phantom only composed by water. Moreover a complete clinical treatment with a multi-shots configuration has also been simulated and also in this case the results were compared with LGP. Some methods for the optimization of the code and the reduction of calculation time are in progress, in order to possibly propose the application as an advanced example of the Geant4 toolkit.
Keymords
Gamma Knife, radiosurgery, gamma, treatment planning system
| Are you a Memeber of the Geant4 Collaboration (yes/no) |
yes
|
Dr
Francesco Romano
(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy)
Dr
Giacomo Cuttone
(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy)
Dr
Giorgio Russo
(Fondazione Istituto San Raffaele - G. Giglio di Cefalù, Palermo, Italy)
Dr
Maria Gabriella Sabini
(Azienda Ospedaliera Cannizzaro, Catania, Italy)
Dr
Vincenza Mongelli
(Azienda Ospedaliera Cannizzaro, Catania, Italy)
