Occupational exposure to electromagnetic fields in magnetic resonance environment: an update on regulation, exposure assessment techniques, health risk evaluation, and surveillance.

Magnetic resonance imaging (MRI) is one of the most-used diagnostic imaging methods worldwide. There are ∼50,000 MRI scanners worldwide each of which involves a minimum of five workers from different disciplines who spend their working days around MRI scanners. This review analyzes the state of the art of literature about the several aspects of the occupational exposure to electromagnetic fields (EMF) in MRI: regulations, literature studies on biological effects, and health surveillance are addressed here in detail, along with a summary of the main approaches for exposure assessment. The original research papers published from 2013 to 2021 in international peer-reviewed journals, in the English language, are analyzed, together with documents published by legislative bodies. The key points for each topic are identified and described together with useful tips for precise safeguarding of MRI operators, in terms of exposure assessment, studies on biological effects, and health surveillance.

Provision of Italian diagnostic reference levels for diagnostic and interventional radiology.

OBJECTIVES: The diagnostic reference level (DRL) is a useful tool for the optimisation of medical exposures. Thus, a Working Party coordinated by the Italian National Institute of Health and the National Workers Compensation Authority has been formed to provide Italian DRLs, for both diagnostic and interventional procedures, to be used as appropriate for the implementation of the 2013/59 European Directive into the national regulation. MATERIALS AND METHODS: The multidisciplinary Working Party was formed by professionals involved in diagnostic and interventional radiology medical exposures and started from a critical revision of both the literature and the results of previous Italian surveys. The procedures were divided into five sections for adult (projection radiography, mammography, diagnostic fluoroscopy, CT and interventional radiology) and two sections for paediatric patients (projection radiography and CT). The provided DRL values have been identified for "normal" adult patients and for age-classes of paediatric patients. RESULTS: Some of the DRL values provided by the Working Party are reported in this study as an example, divided by adult/paediatric patients, radiological technique and examination: specifically, DRLs for new radiological practices and new dose quantities as DRLs metric were introduced. The median value (rather than the mean) for each procedure, derived from a sample of patients, has to be compared with the corresponding DRL value, and dosimetric data related to a minimum number of patients should be collected for each examination. CONCLUSIONS: The approach to the definition and use of DRLs through guidelines of national Authorities in collaboration with scientific Associations should simplify the periodical updating and could be useful for keeping the optimisation of medical exposures faithful to the development of radiological practice.

Summary of the Italian inter-society recommendations for radiation protection optimization in interventional radiology.

OBJECTIVES: A Working Group coordinated by the Italian National Institute of Health (Istituto Superiore di Sanità) and the National Workers Compensation Authority (Istituto Nazionale per l'Assicurazione contro gli Infortuni sul Lavoro, INAIL) and consisting of 11 Italian scientific/professional societies involved in the fluoroscopically guided interventional practices has been established to define recommendations for the optimization of patients and staff radiation protection in interventional radiology. A summary of these recommendations is here reported. MATERIALS AND METHODS: A multidisciplinary approach was used to establish the Working Group by involving radiologists, interventional radiologists, neuroradiologists, interventional cardiologists, occupational health specialists, medical physicists, radiation protection experts, radiographers and nurses. The Group operated as a "Consensus Conference". Three main topics have been addressed: patient radiation protection (summarized in ten "golden rules"); staff radiation protection (summarized in ten "golden rules"); and education/training of interventional radiology professionals. RESULTS: In the "golden rules", practical and operational recommendations were provided to help the professionals in optimizing dose delivered to patients and reducing their own exposure. Operative indications dealt also with continuing education and training, and recommendations on professional accreditation and certification. CONCLUSIONS: The "Consensus Conference" was the methodology adopted for the development of these recommendations. Involvement of all professionals is a winning approach to improve practical implementation of the recommendations, thus getting a real impact on the optimization of the interventional radiology practices.

Leukocyte filtration of blood cardioplegia attenuates myocardial damage and inflammation.

OBJECTIVES: Leukocyte filtration of blood cardioplegia (cLkF) is postulated to reduce ischaemia-reperfusion myocardial injury. Contradictory results have been published and few studies have addressed perioperative cytokine leakage and haemodynamic status after LkF. METHODS: Thirty patients undergoing isolated aortic valve replacement were randomized to cLkF (cLkF-Group) or to standard cold blood cardioplegia (S-Group). Troponin I (TnI) and lactate were sampled from the coronary sinus at reperfusion. Peripheral TnI and lactate were collected preoperatively at admission, and in the intensive care unit (ICU) at 8, 12, 36 and 60 h postoperatively. Cardiac index (CI), indexed systemic vascular resistances, cardiac cycle efficiency (CCE) and central venous pressure (CVP) were registered preoperatively, at admission to the ICU and at the 6th, 12th, 18th, 24th and 36th postoperative hour. IL-6, IL-8, TNF-alpha and IL-10 were sampled preoperatively, at reperfusion, on admission to the ICU and the 6th, 18th and 24th postoperative hours. RESULTS: The cLkF group showed lower TnI (2.4 ± 0.4 vs. 5.1 ± 0.8 µg/l, P = 0.0001) and lactate (0.9 ± 0.1 vs. 1.6 ± 0.2 mmol/l, P = 0.0001) from the coronary sinus at reperfusion. TnI levels (group-P = 0.0001, group time-P < 0.0001) and lactate (group time-P = 0.001) remained lower postoperatively after cLkF. Ventricular defibrillation at aortic declamping was less common in the cLkF-Group (33.3% vs. S-Group: 93.3%; P = 0.002). Cytokines demonstrated significant postoperative leakage (time-P = 0.0001 in both groups for IL-6, IL-8, TNF-alpha, IL-10), with lower pro-inflammatory (IL-6 group-P = 0.0001, group time-P = 0.0001; IL-8 group-P = 0.0001, group time-P = 0.007; TNF-alpha group-P = 0.0001; group time-P = 0.012) and higher anti-inflammatory cytokine secretion after cLkF (IL-10 group-P = 0.005). Perioperative haemodynamic indices proved to be similar between the two groups (group-P = NS for CI, SVRI, CCE and CVP). CONCLUSIONS: cLkF during blood cardioplegia attenuates myocardial ischaemia/reperfusion injury and reduces perioperative leakage of TnI, lactate and pro-inflammatory cytokines. These data did not result in a better haemodynamic status.

How should I wean my next intra-aortic balloon pump? Differences between progressive volume weaning and rate weaning.

OBJECTIVE: Although the intra-aortic balloon pump is the most used ventricular assist device, no study has ever evaluated the best weaning method. We compared 2 different intra-aortic balloon pump weaning methods. METHODS: Thirty consecutive patients needing an intra-aortic balloon pump because of perioperative low-output cardiac syndrome were randomized to be weaned by ratio (4 consecutive hours of a 1:2 assisting ratio followed by 1 hour of a 1:3 ratio; group R) or by progressive volume deflation (10% of total volume every hour for 5 consecutive hours; 15 patients, group V). A duration of 5 hours was set a priori as the weaning duration. The weaning protocol was started when the cardiac index was greater than 2.5 L/min/m(2), the central venous pressure was 12 mm Hg or less, the blood lactate was less than 2.5 mmol/L, the mean arterial pressure was greater than 65 mm Hg, and the preserved urine output (≥1 mL/kg/hr) lasted for at least 5 consecutive hours before weaning. The cardiac index, indexed systemic vascular resistance, cardiac cycle efficiency, and central venous pressure were registered at 9 points (T0, start; T1 to T5, the first 5 weaning hours; T6, 2 hours after withdrawal; T7, 12 hours after withdrawal; and T8, at intensive care unit discharge) using the pressure recording analytical method. The interval from intra-aortic balloon pump withdrawal to intensive care unit discharge, weaning failure, perioperative troponin I, and lactate (same points) were compared. RESULTS: All patients, except for 1 belonging to group R (P = 1.0), were successfully weaned. Group V had better preserved cardiac index, indexed systemic vascular resistance, cardiac cycle efficiency, and central venous pressure (group*time P = .0001). Group R had worse cardiac index from T5 to T8 (P ≤ .0001), indexed systemic vascular resistance from T2 to T8 (P ≤ .004), cardiac cycle efficiency from T3 to T8 (P ≤ .001), central venous pressure from T4 to T8 (P ≤ .0001), and a longer interval from intra-aortic balloon pump withdrawal to intensive care unit discharge (P = .0001). The lactate level was lower in group V from T5 to T8 (P ≤ .027; group*time P = .001). CONCLUSIONS: Intra-aortic balloon pump weaning by volume deflation allowed better hemodynamic and metabolic parameters.

Radiation emission dose from patients administered 90Y-labelled radiopharmaceuticals: comparison of experimental measurements versus Monte Carlo simulation.

AIM: To estimate the radiation dose delivered from patients injected with yttrium-90 (Y)-labelled tiuxetan (Zevalin) to parents and the general population, comparing different techniques. METHODS: The radiation dose delivered from a group of eight patients injected with Y-Zevalin to treat recurrent lymphoma was measured. The data obtained with the Monte Carlo simulation test were compared with the experimental measurements obtained with an ionization chamber detector and with a crystal NaI(Tl) detector. RESULTS: A good correlation was found between the Monte Carlo simulation test and the ionization chamber detector results: the air kerma dose rate was 4.2+/-0.1 and 4.4+/-0.8 microGy/h, respectively (r=0.9, P<0.01). Moreover, more than 99.7% of the air kerma dose rate measured with the ionization chamber detector was because of the contribution of electrons, whereas the contribution of photons was less than 0.3%. In contrast, the air kerma dose rate measured with the crystal NaI(Tl) detector was significantly lower (0.76+0.12 microGy/h) in comparison with the Monte Carlo simulation test. This underestimation was related to the limited crystal NaI(Tl) detector response to low energy rates at variance with the ionization chamber detector. The effective radiation dose released by patients treated with Y-labelled tiuxetan to parents and the general population was approximately 0.1 mSv per treatment cycle. CONCLUSION: Using the Monte Carlo model as a benchmark to compare the experimental measurements obtained by the two different detectors, we found that the ionizing chamber detector was more accurate than the crystal Na(Tl) detector for measuring the exposure radiation dose delivered from patients administered with Y-labelled radiopharmaceuticals. Moreover, the effective radiation dose released by these patients to their parents and the general population is significantly lower than the value recommended by international reports and regulations.