Momennezhad M, Bahreyni Toosi M, Sadeghi R, Gholamhoseinian H, Nasseri S. A Monte Carlo simulation and dosimetric verification of physical wedges used in radiation therapy. Int J Radiat Res 2010; 7 (4) :223-227
URL:
http://ijrr.com/article-1-583-en.html
, NaseriSh801@mums.ac.ir
Abstract: (16595 Views)
Background: The presence of a wedge filter in
the beam trajectory can modify the beam quality and
cause some changes in the dosimetry parameters
which are usually difficult to be measured directly and
accurately. Material and Methods: In this study the
MCNP-4C Monte Carlo code was used to simulate the
9 MV photon beam generated by a linear accelerator.
Upon getting a good agreement between the Monte
Carlo simulated and measured dose distribution in
open fields, the model was used to simulate the
physical wedges. The steel wedges with angles from
15º-60º were modeled and the primary and the
secondary photon beams were calculated. The beam
profiles and wedges factors were calculated for each
wedge. The output factors were determined for 45 wedge. The calculated data were compared with the
measured values of the same parameters. Results:
The results showed that the use of wedges reduced
the fluencies of the primary and scattered photons
and also increased the average energy of the primary
and the scattered photons. The agreement between
the calculated and the measured data was better
than 2% for all wedges. The results also showed that
as the wedge angle increased, the electron contamination
of photon beam decreased. Conclusion: The
presence of a wedge in a 9 MV photon beam alters
the primary and the scattered components generated
by a linear accelerator. The simulated linac machine
and its associated data can be used to predict the
dose distribution in other complex fields. Iran. J.
Radiat. Res., 2010 7 (4): 223-227
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