title: Computer programs for output and depth dose from hyperbolic equations.
abstract: A compact and accurate equation has been developed that describes the output field size over the range from 4 X 4 to 35 X 35 cm2. An accuracy of +/- 0.2% has been demonstrated for teletherapy machines with energies from 250 kVp to 6 MV. The same equation form is used to describe depth dose tables with the same accuracy down to a depth of at least 30 cm. The relationship is described by a hyperbola whose x and y axes are displaced by corresponding values X0 and Y0 producing the equation y = Y0 - C/(X0 + x), where y = output and x = field size. By substituting three separate values for y and x into three simultaneous equations, values for Y0, X0 and c can be derived.
mesh_terms: D003201:Computers; D006801:Humans; D008962:Models, Theoretical; D009369:Neoplasms / Q000532:radiotherapy; D011829:Radiation Dosage; D011878:Radiotherapy / Q000295:instrumentation