title: A method to relate StarTrack(®) measurements to R50 variations in clinical linacs.
abstract: The relation between the data recorded with any device for the daily checking of the behavior of a clinical linac and the reference magnitudes to be monitored may be unknown. An experimental method relating the energy stability of the electron beam measured with StarTrack(®) to the R50 beam quality index is proposed. The bending magnet current is varied producing a change in the exit energy window and, therefore, a modification of the R50 value. For different values of this current, the output data of StarTrack(®) and the R50, obtained from depth doses measured in a water phantom are determined. A linear fit between both sets of data allows the identification of the StarTrack(®) output that provides the best way to obtain the quality index R50, for each beam nominal energy. Using these fits, an historical datum series is used to analyze the method proposed in the daily quality control. The ouput data of the StarTrack(®) and the R50 values show a good linear correlation. It is possible to establish a methodology that allows the monitoring of R50 by direct use of the daily quality control data measured with StarTrack(®). A method to monitor R50 in the daily quality control using the StarTrack(®) device has been developed. The method may be applied to similar devices in which the statistical control variable does not show a linear behavior with R50.
authors.affiliation: Servicio de Radiofísica, Hosp. Univ. "San Cecilio", Avda Dr. Olóriz, 16, E-18012 Granada, Spain. Electronic address: jasx77@gmail.com.
authors.forename: J M
authors.initials: JM
authors.lastname: de la Vega
authors.affiliation: Departamento de Oncología Radioterápica, Clínica Santa María, Avda Santa María, 0500, 7520378 Santiago de Chile, Chile.
authors.forename: S
authors.initials: S
authors.lastname: Ruiz-Arrebola
authors.affiliation: Servicio de Radiofísica, Hosp. Univ. "San Cecilio", Avda Dr. Olóriz, 16, E-18012 Granada, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Tornero-López
authors.affiliation: Unidad de Radiofísica, IMOMA (Instituto de Medicina Oncológica y Molecular de Asturias), Avda Richard Gangrio, s/n, E-33193 Oviedo, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Vilches
authors.affiliation: Servicio de Radiofísica, Hosp. Univ. "San Cecilio", Avda Dr. Olóriz, 16, E-18012 Granada, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Guerrero
authors.affiliation: Servicio de Radiofísica, Hosp. Univ. "San Cecilio", Avda Dr. Olóriz, 16, E-18012 Granada, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Guirado
authors.affiliation: Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Lallena
mesh_terms: D004583:Electrons; D059346:Magnets; D010315:Particle Accelerators / Q000592:standards*; D011786:Quality Control; D011874:Radiometry; D012016:Reference Values
keywords: Electron beams; Quality control; Radiotherapy