Biomaterial Database

Elimination of field size dependence of enhanced dynamic wedge factors. 2000

A Sethi, and L B Leybovich, and N Dogan, and G P Glasgow

Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL 60153, USA. asethi@rdth.rdth.luc.edu

Enhanced dynamic wedge factors (EDWF) are characterized by a strong field size dependence. In contrast to physical wedge factors, the EDWF decrease as the field size is increased: for 6 MV 60 degrees wedge, the EDWF decreases by 50% when the field size is increased from 4 x 4 cm2 to 20 x 20 cm2. A method that eliminates the field size dependence of EDWF was developed and investigated in this work. In this method, the wedged field shape is determined by a multileaf collimator. The initial position of the moving Y jaw is determined by the field size and the stationary Y jaw is kept fixed at 10 cm for field sizes < or = 20 cm in the wedged direction. For all other fields, the stationary Y jaw setting is determined by the field size. The modified method results in EDWF that are independent of field size, with no change in the wedge dose distribution when compared with the conventional use of EDW.

UI	MeSH Term	Description	Entries
D015233	Models, Statistical	Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.	Probabilistic Models,Statistical Models,Two-Parameter Models,Model, Statistical,Models, Binomial,Models, Polynomial,Statistical Model,Binomial Model,Binomial Models,Model, Binomial,Model, Polynomial,Model, Probabilistic,Model, Two-Parameter,Models, Probabilistic,Models, Two-Parameter,Polynomial Model,Polynomial Models,Probabilistic Model,Two Parameter Models,Two-Parameter Model
D017785	Photons	Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)
D020266	Radiotherapy, Conformal	A therapy using IONIZING RADIATION where there is improved dose homogeneity within the tumor and reduced dosage to uninvolved structures. The precise shaping of dose distribution is achieved via the use of computer-controlled multileaf collimators.	Conformal Radiotherapy,3-D Conformal Radiotherapy,Three-Dimensional Conformal Radiotherapy,3-D Conformal Radiotherapies,Conformal Radiotherapies,Conformal Radiotherapies, 3-D,Conformal Radiotherapies, Three-Dimensional,Conformal Radiotherapy, 3-D,Conformal Radiotherapy, Three-Dimensional,Radiotherapies, 3-D Conformal,Radiotherapies, Conformal,Radiotherapies, Three-Dimensional Conformal,Radiotherapy, 3-D Conformal,Radiotherapy, Three-Dimensional Conformal,Three Dimensional Conformal Radiotherapy,Three-Dimensional Conformal Radiotherapies