Determination of radiotherapy X-ray spectra using a screen-film system
Related Experiment Video
Updated: Jul 1, 2026

Irradiator Commissioning and Dosimetry for Assessment of LQ α and β Parameters, Radiation Dosing Schema, and in vivo Dose Deposition
Published on: March 11, 2021
1Department of Ionizing Radiation Metrology, Secondary Standards Dosimetry Laboratory, National Institute for Nuclear Research, Salazar, Mexico. hgarnica@cinvestav.mx
Abstract:
A method to determine the X-ray spectrum delivered by a medical linear accelerator is presented. This method consists of an analytical calculation of the primary spectrum using the Schiff bremsstrahlung cross-section formula. A correction factor that accounts for the scatter component of the spectrum is estimated by comparing the signal in two screen-film systems to a theoretical prediction using a model of energy deposition in such detectors. The model makes use of the quantum absorption efficiency and the average energy deposited per interacting photon concepts. These two quantities are calculated by means of Monte Carlo simulations of the screen-film systems used. This method is capable of determining the spectrum as a function of the spatial position across a plane perpendicular to the beam central axis. It does not, however, render information about the direction cosines of the X-ray fluence crossing such a plane, a requirement in order to produce a full phase-space file that can be used in conjunction with a Monte Carlo dose calculation engine.
Related Concept Videos
Determination of Crystal Structures
Spectrophotometry: Introduction
The essential components of a spectrophotometer include a source of electromagnetic radiation, a slot for placing a material to be analyzed, and a...
X-ray Imaging
IR Spectrometers
UV–Vis Spectrometers
The Electromagnetic Spectrum

