Comparison of dosimetric characteristics of physical wedge and enhanced dynamic wedge in inhomogeneous medium using Monte Carlo simulations

Background: Widely used physical wedges in clinical radiotherapy lead to beam intensity attenuation as well as the beam hardening effect, which must be considered. Dynamic wedges devised to overcome the physical wedges (PWs) problems result in dosimetry complications due to jaw movement while the beam is on. This study was aimed to investigate the usability of physical wedge data instead of enhanced dynamic wedge due to the enhanced dynamic wedge (EDW) dosimetry measurement hardships of Varian 2100CD in inhomogeneous phantom by Monte Carlo code as a reliable method in radiation dosimetry.

Materials and methods: A PW and EDW-equipped-linac head was simulated using BEAMnrc code. DOSXYZnrc was used for three-dimensional dosimetry calculation in the CIRS phantom.

Results: Based on the isodose curves, EDW generated a less scattered as well as lower penumbra width compared to the PW. The depth dose variations of PWs and EDWs were more in soft tissue than the lung tissue. Beam profiles of PW and EDW indicated good coincidence in all points, except for the heel area.

Conclusion: Results demonstrated that it is possible to apply PW data instead of EDW due to the dosimetry and commissioning hardships caused by EDW in inhomogeneous media.