Saw C B, Pawlicki T, Wu A, Ayyangar K M
Division of Radiation Oncology, West Virginia University School of Medicine, Morgantown 26506.
Int J Radiat Oncol Biol Phys. 1994 Mar 1;28(4):979-83. doi: 10.1016/0360-3016(94)90118-x.
Evaluating the validity of the universal wedge equation over the range of 60Cobalt (60CO) to 25 MV photon beam energies.
The universal wedge equation relates the beam weight of the wedged field to the effective wedge angle produced by combining the wedged field to the nonwedged field and is expressed as tan (theta) = B tan (theta w), where B is the normalized weight imposed on the wedged field, theta w is the maximum wedge angle of the wedge filter, and theta is the effective wedge angle. The isodose distributions from 60Co to 25 MV photon beam energies were used. For each photon energy, the isodose distributions of wedged and nonwedged fields were combined in different proportions. The effective wedge angle was determined from each resultant isodose distribution.
The relationship between the weight of wedged field and the effective wedge angle was found to be nonlinear for wedge filters with maximum wedge angle greater than 30 degrees. The universal wedge equation predicts the effective wedge angle to within 2 degrees compared to the measured value.
评估通用楔形方程在钴 - 60（60Co）至25兆伏光子束能量范围内的有效性。
通用楔形方程将楔形野的射束权重与通过将楔形野与非楔形野组合产生的有效楔形角相关联，表达式为tan(θ)=Btan(θw)，其中B是施加在楔形野上的归一化权重，θw是楔形滤过器的最大楔形角，θ是有效楔形角。使用了从60Co到25兆伏光子束能量的等剂量分布。对于每种光子能量，以不同比例组合楔形野和非楔形野的等剂量分布。从每个所得的等剂量分布确定有效楔形角。
对于最大楔形角大于30度的楔形滤过器，发现楔形野权重与有效楔形角之间的关系是非线性的。与测量值相比，通用楔形方程预测有效楔形角的误差在2度以内。
