X-ray spectra and gamma factors from 70 to 120 kV X-ray tube voltages. (July 2021)

• Record Type: Journal Article
• Authors: Campillo-Rivera, Guillermo Eduardo; Torres-Cortes, Carina Oliva; Vazquez-Bañuelos, Joel; Garcia-Reyna, Mayra Guadalupe; Marquez-Mata, Claudia Angelica; Vasquez-Arteaga, Marcial; Vega-Carrillo, Hector Rene
• Is Part Of: Radiation physics and chemistry. Volume 184(2021)
• Publication Date: 2021-07
• Subjects: X-rays -- Spectra -- Air kerma -- Ambient dose equivalent -- Gamma factors -- Monte Carlo; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2021.109437
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: The energy distribution of photons (spectrum) produced in X-ray generators, or X-ray tubes, depends on current, voltage and the target/filter combination; in turn, the dose depends on the spectrum. During the X-ray tube operation, the dose is due the direct beam or useful beam, the leaking out from the X-ray unit, and those photons scattered by the patient. The dose rate must be reduced to allowable limits using a shielding. In the shielding design an important parameter is the dose normalized to the current and the time, that in this work we named Gamma factor, as the factor used for gamma-ray sources. In this work analog Monte Carlo methods were used to calculate the photon spectra and the Gamma factors for air-Kerma and the Ambient dose equivalent for 70, 80, 90, 100 and 120 kV X-ray tubes having tungsten target and aluminum filter. The mean energies of photon spectra were calculated and the conversion coefficients for H*(10) and Ka per unit fluence were calculated and compared with the coefficients for monoenergetic photons. The glass enclosure and the filter eliminate the low-energy photons; calculated spectra show the continuous X-ray distribution due to Bremsstrahlung and the discrete distribution, due to characteristics X-rays. Photon fluences and doses depend on the X-ray unit voltage. Both gamma factors are similar to values recommended in norms while the fluence-to-dose (Ka and H*(10)) conversion coefficients in function of the mean energy are larger than the fluence-to-dose conversion coefficients for monoenergetic photons. Highlights: A model of X-ray tube with W-target and Al-filter was built. The X-ray spectra produced by 70–120 kV x-ray tubes were estimated. The Ka and the H*(10) Gamma factors were calculated. The fluence-to-Ka and fluence-to-H*(10) conversion coefficients were calculated.