Cb. Saw et al., VALIDITY OF UNIVERSAL WEDGE EQUATION OVER THE RANGE OF CO-60 TO 25-MVPHOTON-BEAM ENERGIES, International journal of radiation oncology, biology, physics, 28(4), 1994, pp. 979-983
Citations number
8
Categorie Soggetti
Oncology,"Radiology,Nuclear Medicine & Medical Imaging
Purpose: Evaluating the validity of the universal wedge equation over
the range of Cobalt-60 (60CO) to 25 MV photon beam energies. Methods a
nd Materials: The universal wedge equation relates the beam weight of
the wedged field to the effective wedge angle produced by combining th
e 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 we
dged field, theta(w) is the maximum wedge angle of the wedge filter, a
nd theta is the effective wedge angle. The isodose distributions from
Co-60 to 25 MV photon beam energies were used. For each photon energy,
the isodose distributions of wedged and nonwedged fields were combine
d in different proportions. The effective wedge angle was determined f
rom each resultant isodose distribution. Results: The relationship bet
ween the weight of wedged field and the effective wedge angle was foun
d to be nonlinear for wedge filters with maximum wedge angle greater t
han 30-degrees. The universal wedge equation predicts the effective we
dge angle to within 2-degrees compared to the measured value.