Harmonization and Standardization: Where Are We Now?

Background The purpose of a medical laboratory test is to provide information on the pathophysiologic condition of an individual patient as an aid in diagnosis, therapy, or assessment of risk for a disease. For optimal laboratory service, results from different measurement procedures (MPs) for the same measurand should be equivalent (harmonized) within stated specifications, enabling the results to be used reliably for medical decisions. The term “harmonization” refers to any process that enables establishing equivalence of reported values among different end-user MPs. The term “standardization” refers to achieving harmonization by metrological traceability of patients’ results to higher order reference materials and/or reference measurement procedures. Content New procedures for harmonization and standardization were published in 2020 by the International Organization for Standardization (ISO) and by the IFCC. ISO 17511:2020 provides revised requirements for establishing metrologically traceable calibration hierarchies for end-user MPs used in clinical laboratories. ISO 21151:2020 provides new requirements to implement a harmonization protocol to address the situation when there are no fit-for-purpose certified reference materials or reference MPs available for a measurand. The IFCC Working Group on Commutability published recommendations for applying a correction for noncommutability of a certified reference material to enable using that material in a metrologically traceable calibration hierarchy for an end-user MP. Summary We review metrological traceability and how these new approaches will improve the capability to achieve harmonized results for clinical samples.

Comparing the adiabatic and isothermal pressure dependence of the index of refraction in a drop-weight apparatus

We have investigated the difference between adiabatic and isothermal compression of liquids by an impacting weight, as observed in the resulting change to the index of refraction. The liquids examined were sebacate, glycerol, and water. For practical reasons, sebacate is best suited for the use of a drop-weight apparatus as a metrologically traceable calibration facility for dynamic pressure. We find that its optical properties under adiabatic and isothermal compression can be converted into each other using literature values of its thermodynamic properties. Care has to be taken to avoid cavitation-like effects, an observation that might need to be taken into account for other methods of generating short pressure pulses in the hundreds-of-MPa range.

Developments and Progress in Non-contact Eye Tonometer Calibration

This paper focuses on the problematic of intraocular pressure (IOP) measurements, performed by non-invasive methods. More specifically, the devices that are connected with the presented finding are non-contact tonometers that use concentrated air stream and optical sensors to determine the IOP within a human’s eye. The paper analyzes various influential factors that have an effect on the determination of the IOP values originating from the patients themselves and from the non-contact tonometer devices. The paper furthermore elaborates on the lack of independent methods of calibration and control of these devices. In order to fill this gap a measurement standard device that is capable of calibrating and testing these devices with traceability to the basic SI unit is presented. A detailed characterization and the determination of the expected uncertainty of the device are provided. By introducing an independent and traceable calibration method and control of non-contact tonometers into the clinical practice, the reliability of the measured IOP that is the primary indicator of glaucoma can be improved.

Extending the Global Space-Based Inter-Calibration System (GSICS) to Tie Satellite Radiances to an Absolute Scale

The Global Space-based Inter-Calibration System (GSICS) routinely monitors the calibration of various channels of Earth-observing satellite instruments and generates GSICS Corrections, which are functions that can be applied to tie them to reference instruments. For the infrared channels of geostationary imagers GSICS algorithms are based on comparisons of collocated observations with hyperspectral reference instruments; whereas Pseudo Invariant Calibration Targets are currently used to compare the counterpart channels in the reflected solar band to multispectral reference sensors. This paper discusses how GSICS products derived from both approaches can be tied to an absolute scale using specialized satellite reference instruments with SI-traceable calibration on orbit. This would provide resilience against gaps between reference instruments and drifts in their calibration outside their overlap period and allow construction of robust and harmonized data records from multiple satellite sources to build Fundamental Climate Data Records, as well as more uniform environmental retrievals in both space and time, thus improving inter-operability.

A measurement study ear simulators being in use in Poland and the influence of their acoustic parameters on hearing tests and assessment

Ear simulators are used for traceable calibration and testing of audiometric equipment. They should be periodically calibrated because their parameters can change over time affecting the results of audiometric equipment calibration and, consequently, the results of hearing tests and assessment. During calibration two acoustic parameters are determined: the overall pressure sensitivity level of the ear simulator system and acoustical impedance of the ear simulator, which is additionally assessed in terms of compatibility with IEC 60318-1:2009. The sensitivity level is used for assuring traceability of measurements while acoustical impedance provides information on the condition of a given ear simulator. There are two objectives of this paper. The first is to show how a change in acoustical impedance influences the response of the ear simulator system to a signal from an audiometric earphone. The other is to present the results of a measurement study on acoustic parameters of ear simulators in use in Poland. The article presents the results of measurements of the sensitivity level and acoustical impedance of ear simulators, and the assessment of simulators in the term of their suitability for calibration of audiometric equipment.