Abstract
The Gamma Knife PerfexionTM (Elekta Oncology Systems) is a specialized stereotactic radiotherapy device that uses 192 Cobalt-60 radioactive sources. A dynamic collimator system enables three circular field sizes of 4 mm, 8 mm, and 16 mm diameter to be delivered. This study investigates the dosimetric characteristics of the three different sized collimated beams using Monte Carlo (MC) simulations. The MC simulation made use of previously calculated phase space from a Monte-Carlo model of the encapsulated Cobalt-60 sources. The collimators were modelled using the FLATFILT component module of the BEAMnrc user code. The output of the single beam radiation was stored in a circular scoring plane with a radius of 1.4 cm at source surface distance (SSD) 17.20 cm in the phase space file. The simulation parameters were used 2.1 x 109 particles, electron cut off energy (ECUT) of 0.7 MeV, and photon cut off energy (PCUT) of 0.01 MeV. To investigate the physical full width at half maximum (FWHM) and penumbra width (80-20%), the single beam profiles and mean energy were obtained using BEAMnrc/BEAMDP code. Based on the results that there was an increase of the full width at half maximum (FWHM) with the size of the collimator on the beam profile and the mean energy. The FHWM of the energy fluence profile for the collimator 4, 8, and 16 mm are 2.22, 3.90, and 7.80 mm, respectively. The FHWM of the fluence profile for the collimator sizes 4, 8, and 16 mm are 1.87, 3.87, and 7.80 mm. The FHWM of mean energy as a function of position for the collimator sizes 4, 8, and 16 mm are 2.56, 4.20, and 7.94 mm, respectively. The maximum mean energy for the collimators decreases as much as 0.0185 MeV.
Highlights
The Gamma Knife PerfexionTM (Elekta Oncology Systems) delivers a highly focussed dose of ionizing radiation from 192 Cobalt-60 radioactive sources
A mechanical collimator system made of tungsten is organized into eight sectors of 24 beams that are spherically arranged around the isocentre
The results from this study showed that the ratio of the penumbra width to the field size decreases with increasing field size, which emphasizes the importance of penumbra in smaller field sizes
Summary
The Gamma Knife PerfexionTM (Elekta Oncology Systems) delivers a highly focussed dose of ionizing radiation from 192 Cobalt-60 radioactive sources. This technique is known as stereotactic radiosurgery (SRS), which is typically used to irradiate cranial tumours and functional abnormalities with high geometric precision while conserving normal tissue [1, 2]. A mechanical collimator system made of tungsten is organized into eight sectors of 24 beams that are spherically arranged around the isocentre
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.