Using Monte Carlo (with Geant4) and COMSOL simulations, the authors have defined a useful tool to reproduce the alpha spectroscopy of ²²²Rn, ²²⁰Rn and their ionized daughters by measurement systems based on electrostatic collection on a silicon detector, inside a metallic chamber. Several applications have been performed: (i) simulating commercial devices worldwide used, and comparing them with experimental theoretical results; (ii) studying of realization of new measurement systems through investigation of the detection efficiency versus different chamber geometries. New considerations and steps forward have been drawn. The present work is a novelty in the literature concerning this research framework.

X-ray medical imaging developments have introduced needs for updated dosimetry practices. Performance of commercially available dosimeters used for air kerma measurements in diagnostic and interventional radiology was examined. Ionization chambers and X-ray multimeters were tested in a wide range of air kerma rates, photon energies (using standard and non-standard radiation qualities), and angles of incidence with different dosimeter orientation and rotation. Stability and repeatability of the measured value, the influence of pulse duration, non-linearity of dosimeter response, energy and angular dependence were studied against the IEC 61674:2024 limits of variation. Energy response was tested using the standard RQR and RQT radiation qualities defined in IEC 61267:2005, as well as non-standard copper-filtered beams with added 0.9 mm Cu filtration. Most dosimeters complied with the IEC 61674:2024 standard limits of variation, for both standard and non-standard radiation fields. In some cases, observed performance was significantly better than the current limits allowing for the introduction of more stringent values. Modification of the performance requirements was proposed, considering differences between reference-class and field-class dosimeters, while introducing more stringent requirements for reference-class dosimeters.

The effect of mammography measurement conditions was investigated to evaluate their impact on measurement uncertainties in clinical practice. The most prominent physical X-ray beam quantities i.e., - air kerma, half-value layer, and X-ray tube voltage - were examined by measuring the response of two ionization chambers and six X-ray multimeters (XMMs) of different models. Measurements were performed using several anode/filter combinations and both with and without the compression paddle in the X-ray beam. Maximum differences of higher than 6 % were found for all quantities when the dosimeter displayed value was compared with the reference value or the variation within the clinical anode/filter combinations Mo/Mo and Mo/Rh were considered. The study showed that the calibration procedure with the W/Al anode/filter combination was reliable only for ionization chambers, and the response of XMMs varies in such a way that the calibration coefficient cannot be predicted between various measurement conditions used in calibration and clinical practices. XMM calibrations are typically performed without a compression paddle in the beam, and the response of the XMM changes when radiation quality is slightly altered. If XMM specific data is not available, based on this study, an additional uncertainty of 2 % (k = 1) could be used as a typical estimate, at least for air kerma measurements. XMMs should be used for clinical measurements in mammography only with correct settings. If the correct settings are not available, the XMMs should not be used or used only with extreme caution.

Optimization and quality control of the diagnostic and interventional radiology procedures is usually performed with an X-ray multimeter (XMM) based on the non-invasive measurements of different X-ray tube and output parameters obtained from the X-ray beam, such as air kerma, tube voltage and half-value layer. Standardization and metrological support need to be improved, and harmonized calibration procedures are not available for all quantities. There is also a lack of data on performance of XMMs in different measurement conditions relevant for clinical practice. The needs for calibration of XMMs and current state of the art of calibration services were investigated by performing an overview of the standards, conducting surveys addressed to the clinical medical physicists and calibration laboratories and investigating the key comparison database. There are widely available calibration services for air kerma measurements for a large range of radiation qualities. However, there is a lack of calibration services for all other measured quantities, and very few laboratories besides the manufacturers are able to perform these calibrations. In addition, standardization gaps with non-harmonized calibration and measurement procedures for these quantities were found. New calibration services with harmonized procedures are needed for XMMs, especially for quantities beyond air kerma. There is a need to better understand and reduce measurement uncertainty for some quantities. New procedures will be developed within the TraMeXI project and disseminated to the standardization bodies, metrology and medical physics community.

This study presents the measured X-ray fluence spectra emitted by 15 diagnostic and interventional radiology X-ray imaging devices. The results, comprising more than 180 different spectra, may be used as a compendium and as a basis for further studies in medical X-ray applications. The measurements were conducted using a compact cadmium telluride (CdTe) spectrometer at multiple sites across Europe. The measured half-value layer (HVL) values spanned a wide range, confirming the need for new reference radiation qualities (RRQs) for calibrating medical diagnostic dosimeters. A new set of copper-filtered RRQs is proposed based on existing RQR qualities with filtration complemented with 0.1 mm, 0.3 mm, and 0.9 mm Cu. The new RRQs were designed to comprehensively cover the clinically relevant tube voltage–HVL range of diagnostic and interventional radiology radiation qualities. This will help reduce uncertainties in dosimetry measurements for medical physicists and technical services. Effects of the voltage ripple, the difference of actual and nominal tube voltage, influence of the patient table with mattress, presence of rhenium in the anode, and anode ageing recognized in some measured spectra are illustrated. Influence of anode ageing is compared with SpekPy calculations. The findings underline the practical applicability and relevance of in-beam X-ray spectrometry under clinical conditions, but also describe the persistent challenges in implementing routine spectrometric measurements.

The ISO 4037:2019 standard is the reference standard for dosimetry laboratories who wish to realize dosimetric operational quantities for radiation protection calibrations. In implementing the ISO 4037:2019 standard, the X-ray radiation qualities need to be defined according to strict requirements on the material and thickness of the additional filtration, and according to metrologically traceable high voltage bias applied to the X-ray tube. This enables usage of standardized conversion coefficient from air kerma to operational quantities. However, the tube potential may vary as a function of tube current if a protective resistor is built into the protective tube housing, which, if not corrected, alters the energy distributions of the reference field and thus the value of the appropriate conversion coefficients. Particularly at low energies, the energy dependence of the conversion coefficients can be sharp and, depending on the specific realization of a radiation quality, the conversion coefficient from air kerma to dose equivalent can vary substantially. We have investigated the correspondence between the tube voltage measurements of a X-ray system based on calibrated voltage dividers and that of an X-ray spectrometer system based on a Cadmium Telluride (CdTe) detector in order to obtain an estimation of the resistance of the protective resistor that is usually unknown. A method based on X-ray spectrometry for calibration of the tube potential even in the presence of tube with protective resistor is presented. Finally, conversion coefficients were calculated using simulated spectra to study the influence of the protective resistor on the determination of these coefficients. The simulated spectra obtained from X-ray tube with and without a protective resistor resulted in differences in conversion coefficients mostly ˂2% but 5.6% for the radiation quality considered at the lowest energy.