Monte Carlo study on beam hardening effect of physical wedges

Irregular body contour and tumor volumes necessitate beam modi iers such as physical wedges to achieve a better uniformity of dose distribution (1‐3). With the increasing interest in intensity modulated radiation therapy (IMRT), using of physical wedges has been reduced for ield shaping. On the other hand, IMRT includes a small fraction of the overall treatment techniques for several reasons such as equipment capabilities, heavy maintenance program and labor burden. Thus physical wedges are still widely used as common intensity beam modi ier devices in external beam radiation therapy (2, 5‐7). Radiation therapy relies on knowledge of the penetration of the beam into or through the patient; also the presence of a beam modi ier as physical wedge in the beam trace changes the beam quality and makes some changes in the depth dose distribution which may not be accounted for many treatment planning systems (TPS) (3, 8‐10). So complete knowledge of the dosimetric characteristics of beams is decretive in proper choice of particular wedge in clinical Gh. Geraily1, M. Mirzapour2, S.R. Mahdavi1*, M. Allahverdi3, A. Mostaar4, M. Masoudifar5