Adlington reported in mid-2021 that the number one aim in radiation safety is to keep exposure as low as is reasonably achievable (ALARA), [just as in electrical safety where "hot wires" may be present]. Still, there exist international [Reference 1] and national [2,3] regulations on occupational radiation safety, as well as institutional policies (e.g., [4]) limiting the amount of radiation a person should be exposed to in their work.
Operating a handheld/portable x-ray fluorescence (XRF) spectrometer is not generally considered a highly risky endeavor in terms of radiation exposure, yet there is frustratingly little data available on the subject [5]. This paper shares data from a real-life practical application and compares the radiation levels to an international safety standard, in order to contribute data where there seems to be a relative dearth, so that handheld XRF operators might inform themselves more fully about the risks associated with their work.
The author's coverage is limited, however, in that the tests are carried out on one type of material (glass) with one instrument with limited settings and at relatively infrequent intervals (every 10 s), as the aim was to gain a general idea of the radiation exposure in advance of a specific series of planned tests. If radiation exposure is of particular concern to an individual operating handheld XRF, or if exposure needs to be monitored for any reason, the operator
should wear a dosimeter and/or conduct tests with their own XRF instrument, using their own normal operational settings, on materials related to their samples and research.
The tests reported by this author were partly motivated by the general lack of data, but were also completed as part of the development of a customized attachment for handheld XRF that allows the quantitative or semi-quantitative analysis of window glass, in particular where the window pieces are too small to accommodate the full size of the spectrometer’s face [6].
Medieval stained glass windows, particularly, are characterized by small glass pieces encased in lead cames. The inability to put the spectrometer flush on the glass surface creates distance between the sample and spectrometer that varies from sample to sample, resulting in the reduction of the measured intensity to varied degrees and disrupting the accuracy and precision of the results. The purpose of the attachment, therefore, is to maintain a constant distance between the sample and detector, so that good precision is preserved and the resulting decrease in measured intensity could be corrected through empirical calibration [7].
The attachment, nicknamed the WindoLyzer, was 3D-printed in a material composed of very light elements (polylactic acid, C2H4O2), which would not interfere with analysis but also would not attenuate scattered x-rays. Because of the distance and the lack of attenuation, it was anticipated that the use of the WindoLyzer attachment might increase radiation risks to the operator, necessitating health and safety tests.
The author concluded that in the effort to keep radiation exposure as low as possible, it is advisable to use a lead shield for tabletop analyses, and if possible, use a supporting structure such as a small tripod to hold the spectrometer so that the analyst can step back during operation. Similarly, when analyzing materials that have been secured in an upright position (see Figure 1, right), the use of a full-sized tripod not only alleviates the strain on the analyst’s arms and the risk of pressure on the sample, but also allows the analyst to step back several paces during analysis, greatly reducing exposure.
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