title: A method of measuring the primary dose component in high-energy photon beams.
abstract: We present an approach for deriving the primary component of dose from measurements in a megavoltage gamma or x-ray beam. The theoretical development of the approach is discussed showing that primary dose can be obtained from four measurements of ionization in narrow beam geometry and two measurements of ionization in a large beam in a phantom. The uncertainty in the final result is analyzed and is about an order of magnitude greater than the uncertainty in an individual measurement.
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D006801:Humans; D008962:Models, Theoretical; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D012542:Scattering, Radiation