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:: Volume 5, Issue 1 (6-2007) ::
Int J Radiat Res 2007, 5(1): 31-36 Back to browse issues page
Comparison of measured and Monte Carlo calculated dose distributions from “circular collimators” for radiosurgical beams
K.N. Esnaashari , M. Allahverdi, H. Gharaati, M. Shahriari
, asnaasharikh@razi.tums.ac.ir
Abstract:   (15181 Views)

Background: Stereotactic radiosurgery is an important clinical tool for the treatment of small lesions in the brain, including benign conditions, malignant and localized metastatic tumors. A dosimetry study was performed for Elekta ‘Synergy S ’ as a dedicated Stereotactic radiosurgery unit, capable of generating circular radiation fields with diameters of 1-5 cm at isocentre using the BEAM/EGS4 Monte Carlo code. Materials and Methods: The linear accelerator Elekta “Synergy S” equipped with a set of 5 circular collimators from 10 mm to 50 mm in diameter at isocentre distance was used. The cones were inserted in a base plate mounted on the collimator linac head . A PinPoint chamber and Wellhofer water tank chamber were selected for clinical dosimetry of 6 MV photon beams. The results of simulations using the Monte Carlo system BEAM/EGS4 to model the beam geometry were compared with dose measurements . Results: An excellent agreement was found between Monte Carlo calculated and measured percentage depth dose and lateral dose profiles which were performed in water phantom for circular cones with 1, 2, 3, 4 and 5 cm in diameter. The comparison between calculation and measurements showed up to 0.5 % or 1mm difference for all field sizes. The penumbra (80-20%) results at 5 cm depth in water phantom and SSD=95 ranged from 1.5 to 2.1 mm for circular collimators with diameter 1 to 5 cm . Conclusion: This study showed that BEAMnrc code has been accurate in modeling Synergy S linear accelerator equipped with circular collimators.

Keywords: Monte Carlo, dosimetry, radiosurgery, circular cones.
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Type of Study: Original Research | Subject: Medical Physics
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Esnaashari K, Allahverdi M, Gharaati H, Shahriari M. Comparison of measured and Monte Carlo calculated dose distributions from “circular collimators” for radiosurgical beams. Int J Radiat Res. 2007; 5 (1) :31-36
URL: http://ijrr.com/article-1-291-en.html

Volume 5, Issue 1 (6-2007) Back to browse issues page
International Journal of Radiation Research
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