Study of the influence of atmospheric air climatic parameters on the air kerma measurements in low energy X reference radiation fields

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2019-02, Vol.155, p.328-331
• Main Authors: Figueiredo, M.T.T., Lacerda, M.A.S., da Silva, T.A.
• Format: Article
• Language: English
• Subjects: Climate change; Computer simulation; Density; Dosimeters; Dosimetry; Humidity; Low energy X-ray beam; Message passing; Monte Carlo simulation; Parameters; Standardization; X-ray dosimetry; X-rays
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2018.08.031

The control of climatic conditions in a radiation metrology laboratory is very important. Air pressure, temperature and humidity affect the value of the air density, and, consequently, alter the absorption of the photon radiation. Then, the values of the air kerma Ka, conversion coefficients from Ka to the dose equivalent quantities (hp,K(10,α) and h*K(10)) and their product (Hp(10) and H*(10)) are affected by climatic changes. For low energy X radiation fields, changes in climatic conditions are more critical. The International Organization for Standardization (ISO), via the ISO 4037-4, specifies corrections for air density for all quantities defined in 10 mm depth in tissue for nominal tube potentials varying from 10 kV to 30 kV (inclusive). In this work, we utilized monte carlo method to evaluate the influence of atmospheric air climate parameters on the air kerma measurements, for the ISO low energies, series N and L. Simulations were performed using the MCNPX code version 2.7.d, running under MPI (Message Passing Interface) on a computational cluster. We simulated the air with different humidity levels, and consequently, different densities and elemental compositions. The ISO 4037 reference beams of the Dosimeters Calibration Laboratory of the Nuclear Technology Development Center (LCD/CDTN) were utilized to validate the Monte Carlo simulations. •Conversion coefficients showed to be extremely dependent on the incident photon energy for the energies up to 30 keV.•Air density depend of climatic parameters.•MCNPX code was used to model and assess correction factors in dosimetry of low energy X-rays.