The influence of operator position, height and body orientation on eye lens dose in interventional radiology and cardiology: Monte Carlo simulations versus realistic clinical measurements

Objective:This paper aims to provide some practical recommendations to reduce eye lens dose for work-ers exposed to X-rays in interventional cardiology and radiology and also to propose an eye lens correc-tion factor when lead glasses are used.Methods:Monte Carlo simulations are used to study the variation of eye lens exposure with operatorposition, height and body orientation with respect to the patient and the X-ray tube. The paper also looksinto the efficiency of wraparound lead glasses using simulations. Computation results are compared withexperimental measurements performed in Spanish hospitals using eye lens dosemeters as well as withdata from available literature.Results:Simulations showed that left eye exposure is generally higher than the right eye, when the oper-ator stands on the right side of the patient. Operator height can induce a strong dose decrease by up to afactor of 2 for the left eye for 10-cm-taller operators. Body rotation of the operator away from the tube by45°–60°reduces eye exposure by a factor of 2. The calculation-based correction factor of 0.3 for wrap-around type lead glasses was found to agree reasonably well with experimental data.Conclusions:Simple precautions, such as the positioning of the image screen away from the X-ray source,lead to a significant reduction of the eye lens dose. Measurements and simulations performed in thiswork also show that a general eye lens correction factor of 0.5 can be used when lead glasses are wornregardless of operator position, height and body orientation.Postprint (author's final draft

Cell to Cell Variability of Radiation-Induced Foci : relation between Observed Damage and Energy Deposition

Most studies that aim to understand the interactions between different types of photon radiation and cellular DNA assume homogeneous cell irradiation, with all cells receiving the same amount of energy. The level of DNA damage is therefore generally determined by averaging it over the entire population of exposed cells. However, evaluating the molecular consequences of a stochastic phenomenon such as energy deposition of ionizing radiation by measuring only an average effect may not be sufficient for understanding some aspects of the cellular response to this radiation. The variance among the cells associated with this average effect may also be important for the behaviour of irradiated tissue. In this study, we accurately estimated the distribution of the number of radiation-induced γH2AX foci (RIF) per cell nucleus in a large population of endothelial cells exposed to 3 macroscopic doses of gamma rays from 60Co. The number of RIF varied significantly and reproducibly from cell to cell, with its relative standard deviation ranging from 36% to 18% depending on the macroscopic dose delivered. Interestingly, this relative cell-to-cell variability increased as the dose decreased, contrary to the mean RIF count per cell. This result shows that the dose effect, in terms of the number of DNA lesions indicated by RIF is not as simple as a purely proportional relation in which relative SD is constant with dose. To analyse the origins of this observed variability, we calculated the spread of the specific energy distribution for the different target volumes and subvolumes in which RIF can be generated. Variances, standard deviations and relative standard deviations all changed similarly from dose to dose for biological and calculated microdosimetric values. This similarity is an important argument that supports the hypothesis of the conservation of the association between the number of RIF per nucleus and the specific energy per DNA molecule. This comparison allowed us to calculate a volume of 1.6 μm3 for which the spread of the specific energy distribution could explain the entire variability of RIF counts per cell in an exposed cell population. The definition of this volume may allow to use a microdosimetric quantity to predict heterogeneity in DNA damage. Moreover, this value is consistent with the order of magnitude of the volume occupied by the hydrated sugar-phosphate backbone of the DNA molecule, which is the part of the DNA molecule responsible for strand breaks

Recommendations for the use of active personal dosemeters (APDs) in interventional workplaces in hospitals

Occupational radiation doses from interventional procedures have the potential to be relatively high. The requirement to optimise these doses encourages the use of electronic or active personal dosimeters (APDs) which are now increasingly used in hospitals. They are typically used in tandem with a routine passive dosimetry monitoring programme, with APDs used for real-time readings, for training purposes and when new imaging technology is introduced. However, there are limitations when using APDs. A survey in hospitals to identify issues related to the use of APDs was recently completed, along with an extensive series of APD tests by the EURADOS Working Group 12 on Dosimetry for Medical Imaging. The aim of this review paper is to summarise the state of the art regarding the use of APDs. We also used the results of our survey and our tests to develop a set of recommendations for the use of APDs in the clinical interventional radiology/cardiology settings, and draw attention to some of the current challenges.Peer ReviewedPostprint (published version

What Is Worth Knowing in Interventional Practices about Medical Staff Radiation Exposure Monitoring: A Review of Recent Outcomes of EURADOS Working Group 12

EURADOS (European Radiation Dosimetry Group) Working Group 12 (WG12) SG1 activities are aimed at occupational radiation protection and individual monitoring in X-ray and nuclear medicine practices. In recent years, many studies have been carried out in these fields, especially for interventional radiology and cardiology workplaces (IC/IR). The complexity of the exposure conditions of the medical staff during interventional practices makes the radiation protection and monitoring of the exposed workers a challenging task. The scope of the present work is to review some of the main results obtained within WG12 activities about scattered field characterization and personal dosimetry that could be very useful in increasing the quality of radiation protection of the personnel, safety, and awareness of radiation risk. Two papers on Monte Carlo modelling of interventional theater and three papers on active personal dosimeters (APDs) for personnel monitoring were considered in the review. More specifically, Monte Carlo simulation was used as the main tool to characterize the levels of exposure of the medical staff, allowing to determine how beam energy and direction can have an impact on the doses received by the operators. Indeed, the simulations provided information about the exposure of the operator’s head, and the study concluded with the determination of an eye-lens protection factor when protection goggles and a ceiling shielding are used. Moreover, the review included the results of studies on active personal dosimeters, their use in IC/IR workplaces, and how they respond to calibration fields, with X-ray standard and pulsed beams. It was shown that APDs are insensitive to backscatter radiation, but some of them could not respond correctly to the very intense pulsed fields (as those next to the patient in interventional practices). The measurements during interventional procedures showed the potential capability of the employment of APDs in hospitals

Recommendations for the use of active personal dosemeters (APDs) in interventional workplaces in hospitals

Occupational radiation doses from interventional procedures have the potential to be relatively high. The requirement to optimise these doses encourages the use of electronic or active personal dosimeters (APDs) which are now increasingly used in hospitals. They are typically used in tandem with a routine passive dosimetry monitoring programme, with APDs used for real-time readings, for training purposes and when new imaging technology is introduced. However, there are limitations when using APDs. A survey in hospitals to identify issues related to the use of APDs was recently completed, along with an extensive series of APD tests by the EURADOS Working Group 12 on Dosimetry for Medical Imaging. The aim of this review paper is to summarise the state of the art regarding the use of APDs. We also used the results of our survey and our tests to develop a set of recommendations for the use of APDs in the clinical interventional radiology/cardiology settings, and draw attention to some of the current challenges

Evaluation de la surexposition accidentelle aux rayonnements ionisants : de la dosimétrie physique aux indicateurs biologiques de dommages

En cas d'accident radiologique, il est important de connaître la dose reçue par les victimes. L'utilisation conjointe d'outils basés sur des méthodes de reconstitution physique de l'irradiation et de mesure de la variation de paramètres biologiques permet d'estimer la distribution de la dose dans l'organisme. La dose ne donne toutefois pas d'indication directe sur les effets au niveau des organes c'est pourquoi des indicateurs de dommages sont développés en complément, le but étant d'allier des indicateurs de dommage et de pronostic

Characterisation of two new radiochromic gel dosimeters TruView™ and ClearView™ in combination with the vista™ optical CT scanner: A feasibility study

International audienc

Violet stimulated luminescence signal from electronic components for radiation accident dosimetry

International audienceDue to recent technological advances, new optical stimulation sources with higher energies became commercially available. In the present work, laser diodes emitting in the violet (∼405 nm) were used to investigate dosimetric characteristics of the violet stimulated luminescence (VSL) signal from electronic components (resistors and inductors) extracted from mobile phones. All component types exhibit higher sensitivity using violet stimulation than using blue one. The sensitization was negligible after 10 cycles of irradiation and measurement. The dose response was linear from 0.6 Gy to 30 Gy. Additionally, signal fading of one type of inductors was studied. Results were similar for blue stimulated luminescence (BSL) and VSL signals. Fading measurements performed at 40 °C after a preheat (125 °C hold for 10 s) or at 125 °C indicated low fading rates (∼95% of signal remaining 1 h after irradiation). These preliminary results appear to be promising for retrospective dosimetry

EURADOS 2016 intercomparison exercise of eye lens dosemeters

In the context of a new annual eye lens dose limit for occupational exposure equal to 20 mSv, European Radiation Dosimetry Group (EURADOS) organized an intercomparison dedicated to eye lens dosemeters, including photon and beta radiations. The objective was to complete the first intercomparison recently organized by EURADOS for photons and to update the overview of eye lens dosemeters available in Europe. The dosemeters provided by the 22 participants coming from 12 countries were all composed of thermoluminescent detectors. The dosemeters were irradiated with photon and beta fields defined in relevant standards. The results, provided by participants in terms of Hp(3), were compared to the reference delivered doses. Results are globally satisfactory for photons since 90% of the data are in accordance to the ISO 14146 standard requirements. The respective values for betas stress the fact that dosemeters designed for Hp(0.07) are not suitable to monitor the eye lens dose in case of betas.Postprint (author's final draft