title: Polynomial and power law of central axis backscatter factors for external and gamma-ray sources.
abstract: A third-degree polynomial and power-law analysis with the method of least-squares fit are computed for backscatter factor with a continuous variation of field size and different beam quality of radiation from 1.0-mm Al external x ray to 60Co gamma ray. Three coefficients are required for a third-degree polynomial and two coefficients for power law method of each beam quality.
mesh_terms: D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D005720:Gamma Rays; D011879:Radiotherapy Dosage; D012542:Scattering, Radiation; D014965:X-Rays
chemical_list: D003037:Cobalt Radioisotopes