Implications of X-ray tube parameter deviations in X-ray reference fields

Area of Science:

• Medical Physics
• Radiation Dosimetry
• X-ray Physics

Background:

• ICRU Report 57/ICRP Publication 74 provides conversion coefficients for radiation protection.
• ISO 4037 defines X-ray reference fields but lacks parameter deviation tolerances.
• Deviations in high-voltage, beryllium window, and filter parameters affect X-ray spectra.

Purpose of the Study:

• To investigate the impact of X-ray tube parameter deviations on conversion coefficients.
• To propose revised deviation limits for ISO 4037.
• To ensure the accuracy of radiation protection quantities derived from X-ray reference fields.

Main Methods:

• Utilized a simplified mathematical approximation model to assess parameter impact.
• Validated findings with an independent X-ray spectra calculation program.
• Analyzed the influence of high-voltage potential, beryllium window thickness, and filter properties.

Main Results:

• Parameter variations cause significant changes in X-ray spectra.
• These spectral changes directly affect spectra-dependent conversion coefficients.
• Identified critical deviations that render existing conversion coefficients unusable.

Conclusions:

• Established well-founded upper limit values for X-ray tube parameter deviations.
• Proposed these limits for inclusion in future revisions of ISO 4037.
• Aimed to prevent reliance on costly spectrometry measurements by ensuring accurate X-ray reference fields.