analisi monte carlo mediante il codice mcnp della dose assorbita dalla lente del cristallino da un operatore sanitario in radiologia interventistica

Nello studio svolto ci si è focalizzati sullo sviluppo e sulla validazione di un modello computazionale di occhio umano atto ad ospitare oltre alle varie strutture oculari, nove differenti modelli di cristallino ricreati sulla base di dati geometrici acquisiti "in vivo" mediante il dispoditivo "Oculus Pentacam", su un campione di 50 lavorati dell'ospedale di Reggio Emilia. Sfruttando le tecniche di analisi Monte Carlo, in una prima parte del lavoro (parte A) si è condotta la validazione dei nove differenti modelli. Mediante il codice MCNP è stata simulata una situazione di irraggiamento isotropo con una sorgente puntiforme di fotoni monoenergetici a differenti valori di energia tipici per la radiologia interventistica (10 keV, 20 keV, 30 keV, 50 keV, 70 keV, 100 keV, 150 keV). I modelli geometrici realizzati e i risultati ottenuti sono stati confrontati con dati già presenti in letteratura; in particolare, si sono presi in riferimento gli studi effettuati da El Basha e Behrens, con i rispettivi modelli oculari. Nella seconda parte dello studio (parte B) i modelli sono stati introdotti in una geometria più complessa costituita da due fantocci d’acqua (paziente e operatore sanitario), tavolo operatorio e tubo RX, e rappresentativa di una situazione standard e realistica del settore lavorativo d’interesse. I modelli oculari sono stati dunque testati con i tre diversi spettri energetici a 50 kVp, 75 kVp e 100 kVp validati in precedenti lavori. I valori dei coefficienti di dose per unità di fluenza di particelle [pGy cm^2] e di dose assorbita [pGy], sono stati riportati per ogni sorgente monocromatica della parte A, e per ogni spettro energetico utilizzato come sorgente nella parte B del lavoro, ma anche per ogni modello di cristallino e per ognuna delle altre strutture oculari. Inoltre, per la parte B, oltre alle quantità appena citate si sono stimati e graficati i valori dei coefficienti dose espressi in [pSv h^(-1) cm^2] e del rateo di dose equivalente [pSv h^(-1)]

Virtual simulation with Sim&Size software for Pipeline Flex Embolization: evaluation of the technical and clinical impact

International audienceDuring flow diversion, the choice of the length, diameter, and location of the deployed stent are critical for the success of the procedure. Sim&Size software, based on the three-dimensional rotational angiography (3D-RA) acquisition, simulates the release of the stent, suggesting optimal sizing, and displaying the degree of the wall apposition. Objective To demonstrate technical and clinical impacts of the Sim&Size simulation during treatment with the Pipeline Flex Embolization Device. Methods Consecutive patients who underwent aneurysm embolization with Pipeline at our department were retrospectively enrolled (January 2015–December 2017) and divided into two groups: treated with and without simulation. Through univariate and multivariate models, we evaluated: (1) rate of corrective intervention for non-optimal stent placement, (2) duration of intervention, (3) radiation dose, and (4) stent length. Results 189 patients, 95 (50.2%) without and 94 (49.7%) with software assistance were analyzed. Age, sex, comorbidities, aneurysm characteristics, and operator’s experience were comparable among the two groups. Procedures performed with the software had a lower rate of corrective intervention (9% vs 20%, p=0.036), a shorter intervention duration (46 min vs 52 min, p=0.002), a lower median radiation dose (1150 mGy vs 1558 mGy, p<0.001), and a shorter stent length (14 mm vs 16 mm, p<0.001). Conclusions In our experience, the use of the virtual simulation during Pipeline treatment significantly reduced the need for corrective intervention, the procedural time, the radiation dose, and the length of the stent

DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation

The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20&nbsp;mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25&nbsp;mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation

European Multicenter Study of ET-COVID-19

International audienceBackground and Purpose: Acute ischemic stroke and large vessel occlusion can be concurrent with the coronavirus disease 2019 (COVID-19) infection. Outcomes after mechanical thrombectomy (MT) for large vessel occlusion in patients with COVID-19 are substantially unknown. Our aim was to study early outcomes after MT in patients with COVID-19. Methods: Multicenter, European, cohort study involving 34 stroke centers in France, Italy, Spain, and Belgium. Data were collected between March 1, 2020 and May 5, 2020. Consecutive laboratory-confirmed COVID-19 cases with large vessel occlusion, who were treated with MT, were included. Primary investigated outcome: 30-day mortality. Secondary outcomes: early neurological improvement (National Institutes of Health Stroke Scale improvement ≥8 points or 24 hours National Institutes of Health Stroke Scale 0–1), successful reperfusion (modified Thrombolysis in Cerebral Infarction grade ≥2b), and symptomatic intracranial hemorrhage. Results: We evaluated 93 patients with COVID-19 with large vessel occlusion who underwent MT (median age, 71 years [interquartile range, 59–79]; 63 men [67.7%]). Median pretreatment National Institutes of Health Stroke Scale and Alberta Stroke Program Early CT Score were 17 (interquartile range, 11–21) and 8 (interquartile range, 7–9), respectively. Anterior circulation acute ischemic stroke represented 93.5% of cases. The rate modified Thrombolysis in Cerebral Infarction 2b to 3 was 79.6% (74 patients [95% CI, 71.3–87.8]). Thirty-day mortality was 29% (27 patients [95% CI, 20–39.4]). Early neurological improvement was 19.5% (17 patients [95% CI, 11.8–29.5]), and symptomatic intracranial hemorrhage was 5.4% (5 patients [95% CI, 1.7–12.1]). Patients who died at 30 days exhibited significantly lower lymphocyte count, higher levels of aspartate, and LDH (lactate dehydrogenase). After adjustment for age, initial National Institutes of Health Stroke Scale, Alberta Stroke Program Early CT Score, and successful reperfusion, these biological markers remained associated with increased odds of 30-day mortality (adjusted odds ratio of 2.70 [95% CI, 1.21–5.98] per SD-log decrease in lymphocyte count, 2.66 [95% CI, 1.22–5.77] per SD-log increase in aspartate, and 4.30 [95% CI, 1.43–12.91] per SD-log increase in LDH). Conclusions: The 29% rate of 30-day mortality after MT among patients with COVID-19 is not negligible. Abnormalities of lymphocyte count, LDH and aspartate may depict a patient’s profiles with poorer outcomes after MT. Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT04406090