Lead equivalence testing using a custom-built testing kit

Abstract

Radiation protective garments should undergo a quality assurance regime comprising of an acceptance test of the lead equivalence before the garment is introduced into clinical service, followed by routine periodic visual and fluoroscopic inspections throughout its remaining clinical lifespan. The IEC 61331-1:2014 [1] is the leading standard outlining the methodology for testing of lead equivalence of these garments and forms the basis of the Australian/New Zealand Standards (1999) [2]. This study outlines the design and development of an IEC compliant broad beam lead equivalence testing setup, using an in-house custom-built testing kit (CBTK). The practicality and robustness of this kit was performance tested using lead equivalence measurements on 97% pure lead sheets. Hospital radiation protective garments are predominantly made of lead-free or lead-composite materials due to their light weight, as such, a set of lead-free (N-Pb) samples was also performance tested. These samples were tested using two different beam qualities; a total filtration of 2.5 mmAl and 0.25 mmCu added filtration, both at 102 kVp. Samples with thicknesses of 0.25 mm, 0.35 mm and 0.50 mm were used. The differential between labelled and measured lead equivalence averaged 3% for both the 'pure-lead' samples and N-Pb samples, with uncertainty of less than 7%. At 102 kVp, the use of Cu or Al filtration has marginal effect on measured lead equivalence for pure lead or N-Pb samples. The efficacy of utilizing the CBTK with a solid-state detector for lead equivalence testing was demonstrated through its ease of use, consistency and precision.

Keywords: Broad beam geometry; Custom-built testing kit; Filtration; Lead equivalence testing; Radiation protective garments.