The U.S. Navy uses the Harshaw 8840/8841 dosimetric (DT‐702/PD) system, which employs LiF:Mg,Cu,P thermoluminescent dosimeters (TLDs), developed and produced by Thermo Fisher Scientific (TFS). The dosimeter consists of four LiF:Mg,Cu,P elements, mounted in Teflon® on an aluminum card and placed in a plastic holder. The holder contains a unique filter for each chip made of copper, acrylonitrile butadiene styrene (ABS), Mylar®, and tin. For accredited dosimetry labs, the ISO/IEC 17025:2005(E) requires an acceptance procedure for all new equipment. The Naval Dosimetry Center (NDC) has developed and tested a new non-destructive procedure, which enables the verification and the evaluation of embedded filters in the holders. Testing is based on attenuation measurements of low-energy radiation transmitted through each filter in a representative sample group of holders to verify that the correct filter type and thickness are present. The measured response ratios are then compared with the expected response ratios. In addition, each element’s measured response is compared to the mean response of the group. The test was designed and tested to identify significant nonconformities, such as missing copper or tin filters, double copper or double tin filters, or other nonconformities that may impact TLD response ratios. During the implementation of the developed procedure, testing revealed a holder with a double copper filter. To complete the evaluation, the impact of the nonconformities on proficiency testing was examined. The evaluation revealed failures in proficiency testing categories III and IV when these dosimeters were irradiated to high-energy betas.
*Naval Dosimetry Center, 8950 Brown Drive, Bethesda, MD 20889; †Naval Academy, Annapolis, MD 21402; ‡Naval Surface Warfare Center, Bethesda, 20817, MD.
The authors declare no conflicts of interest.
Alexander Romanyukha has an PhD in solid state physics (Russian Academy of Sciences, 1985). Alexander has been employed for the last 10 years as a Technical Manager of the Naval Dosimetry Center. He has been working in the field of radiation dosimetry since 1992. He served as a Chief Scientific Investigator of the International Atomic Energy Agency (IAEA) research project «Electron Paramagnetic Resonance biodosimetry», a member of the International Committee for Radiation Units (ICRU) Report Committee for Retrospective Assessment of Exposures to Ionizing Radiation, co-authored the IAEA-TECDOC‐1331, ICRU reports 68 and 29, U.S. delegate in the ISO/TC85 WG18. Currently, his research interests include but are not limited to the Electron Paramagnetic Resonance (EPR) dosimetry in tooth enamel, bone and fingernails, TLD and OSL dosimetry. He is the author of more than 130 peer-reviewed publications. His email is firstname.lastname@example.org.