Dosimetry of a portable in vivo X-ray fluorescence system using EBT3 radiochromic film

<p><em>Purpose. In vivo</em> x-ray fluorescence is a non-invasive analytical technique for determining trace and toxic element exposures. In this work we measure the dose for a portable handheld x-ray system (pXRF). <em>Materials and Methods</em>. We used EBT3 radiochromic film calibrated with a clinical orthovoltage unit for absolute dose measurement. Films were placed on a human phantom and irradiated with the Tracer III-SD pXRF at tube potentials of 40 and 45 kVp with various levels of filtration. <em>Results.</em> Using settings that result in the best detection limits, the highest absorbed point dose to the skin was 0.3 Gy, the equivalent dose to a 1 cm2 area was 54 mSv, and the whole-body effective dose was less than 1 <em>μ</em>Sv for a standard 3-min <em>in vivo</em> measurement of strontium or lead. Recent work has demonstrated that 1 s and 30 s measurements are feasible for bone strontium measurements, which would lead to significantly lower doses. <em>Conclusions</em>. Our results are in agreement with a previous dosimetry study of another portable x-ray device and indicate that it is safe for <em>in vivo</em> measurements of elements such as strontium and lead, only after appropriate dose validation and with appropriate beam filtration in place.</p>