Peripheral dose around a mobile linac for intraoperative radiotherapy: radiation protection aspects.

The aim of this work is to analyse the scattered radiation produced by the mobile accelerator Mobetron 1000. To do so, detailed Monte Carlo simulations using two different codes, Penelope2008 and Geant4, were performed. Measurements were also done. To quantify the attenuation due to the internal structures, present in the accelerator head, on the scattered radiation produced, some of the main structural shielding in the Mobetron 1000 has been incorporated into the geometry simulation. Results are compared with measurements. Some discrepancies between the calculated and measured dose values were found. These differences can be traced back to the importance of the radiation component due to low energy scattered electrons. This encouraged us to perform additional calculations to separate the role played by this component. Ambient dose equivalent, H*(10), outside of the operating room (OR) has been evaluated using Geant4. H*(10) has been measured inside and outside the OR, being its values compatible with those reported in the literature once the low energy electron component is removed. With respect to the role played by neutrons, estimations of neutron H*(10) using Geant4 together with H*(10) measurements has been performed for the case of the 12 MeV electron beam. The values obtained agree with the experimental values existing in the literature, being much smaller than those registered in conventional accelerators. This study is a useful tool for the clinical user to investigate the radiation protection issues arising with the use of these accelerators in ORs without structural shielding. These results will also enable to better fix the maximum number of treatments that could be performed while insuring adequate radiological protection of workers and public in the hospital.

Calibration of a thermoluminescent dosimeter worn over lead aprons in fluoroscopy guided procedures.

Fluoroscopy guided interventional procedures provide remarkable benefits to patients. However, medical staff working near the scattered radiation field may be exposed to high cumulative equivalent doses, thus requiring shielding devices such as lead aprons and thyroid collars. In this situation, it remains an acceptable practice to derive equivalent doses to the eye lenses or other unprotected soft tissues with a dosimeter placed above these protective devices. Nevertheless, the radiation backscattered by the lead shield differs from that generated during dosimeter calibration with a water phantom. In this study, a passive personal thermoluminescent dosimeter (TLD) was modelled by means of the Monte Carlo (MC) code Penelope. The results obtained were validated against measurements performed in reference conditions in a secondary standard dosimetry laboratory. Next, the MC model was used to evaluate the backscatter correction factor needed for the case where the dosimeter is worn over a lead shield to estimate the personal equivalent dose H p (0.07) to unprotected soft tissues. For this purpose, the TLD was irradiated over a water slab phantom with a photon beam representative of the result of a fluoroscopy beam scattered by a patient. Incident beam angles of 0° and 60°, and lead thicknesses between the TLD and phantom of 0.25 and 0.5 mm Pb were considered. A backscatter correction factor of 1.23 (independent of lead thickness) was calculated comparing the results with those faced in reference conditions (i.e., without lead shield and with an angular incidence of 0°). The corrected dose algorithm was validated in laboratory conditions with dosimeters irradiated over a thyroid collar and angular incidences of 0°, 40° and 60°, as well as with dosimeters worn by interventional radiologists and cardiologists. The corrected dose algorithm provides a better approach to estimate the equivalent dose to unprotected soft tissues such as eye lenses. Dosimeters that are not shielded from backscatter radiation might underestimate personal equivalent doses when worn over a lead apron and, therefore, should be specifically characterized for this purpose.

The independent role of prenatal and postnatal exposure to active and passive smoking on the development of early wheeze in children.

Maternal smoking during pregnancy increases childhood asthma risk, but health effects in children of nonsmoking mothers passively exposed to tobacco smoke during pregnancy are unclear. We examined the association of maternal passive smoking during pregnancy and wheeze in children aged ≤2 years.Individual data of 27 993 mother-child pairs from 15 European birth cohorts were combined in pooled analyses taking into consideration potential confounders.Children with maternal exposure to passive smoking during pregnancy and no other smoking exposure were more likely to develop wheeze up to the age of 2 years (OR 1.11, 95% CI 1.03-1.20) compared with unexposed children. Risk of wheeze was further increased by children's postnatal passive smoke exposure in addition to their mothers' passive exposure during pregnancy (OR 1.29, 95% CI 1.19-1.40) and highest in children with both sources of passive exposure and mothers who smoked actively during pregnancy (OR 1.73, 95% CI 1.59-1.88). Risk of wheeze associated with tobacco smoke exposure was higher in children with an allergic versus nonallergic family history.Maternal passive smoking exposure during pregnancy is an independent risk factor for wheeze in children up to the age of 2 years. Pregnant females should avoid active and passive exposure to tobacco smoke for the benefit of their children's health.

Paving the way of systems biology and precision medicine in allergic diseases: the MeDALL success story: Mechanisms of the Development of ALLergy; EU FP7-CP-IP; Project No: 261357; 2010-2015.

MeDALL (Mechanisms of the Development of ALLergy; EU FP7-CP-IP; Project No: 261357; 2010-2015) has proposed an innovative approach to develop early indicators for the prediction, diagnosis, prevention and targets for therapy. MeDALL has linked epidemiological, clinical and basic research using a stepwise, large-scale and integrative approach: MeDALL data of precisely phenotyped children followed in 14 birth cohorts spread across Europe were combined with systems biology (omics, IgE measurement using microarrays) and environmental data. Multimorbidity in the same child is more common than expected by chance alone, suggesting that these diseases share causal mechanisms irrespective of IgE sensitization. IgE sensitization should be considered differently in monosensitized and polysensitized individuals. Allergic multimorbidities and IgE polysensitization are often associated with the persistence or severity of allergic diseases. Environmental exposures are relevant for the development of allergy-related diseases. To complement the population-based studies in children, MeDALL included mechanistic experimental animal studies and in vitro studies in humans. The integration of multimorbidities and polysensitization has resulted in a new classification framework of allergic diseases that could help to improve the understanding of genetic and epigenetic mechanisms of allergy as well as to better manage allergic diseases. Ethics and gender were considered. MeDALL has deployed translational activities within the EU agenda.

Preliminary study on serum paraoxonase-1 status and chemokine (C-C motif) ligand 2 in hospitalized elderly patients with catheter-associated asymptomatic bacteriuria.

Urinary tract infections (UTI) are common among elderly patients in residential care facilities, as well as in the hospital setting. Identifying new biochemical markers of UTI is an active line of research since UTI management is resource intensive. Paraoxonase-1 (PON1) forms part of the patient's immune system, the response-to-injury and inflammation. Our study sought to evaluate alterations in inflammation-related paraoxonase-1 (PON1) and chemokine (C-C motif) ligand 2 (CCL2) in patients with an indwelling catheter to assess their potential usefulness as biomarkers of infection. Patients (n = 142) who had had the urinary catheter removed and 100 healthy volunteers were recruited. In all participants we measured serum PON1 activity, PON1 concentration, CCL2, procalcitonin and C-reactive protein (CRP). Results indicated that patients had higher CCL2, CRP and procalcitonin concentrations than the control group, and lower paraoxonase activity. There were no significant differences in PON1 concentrations. When comparing the diagnostic accuracy of CRP, procalcitonin, CCL2 and the PON1-related variables in discriminating between patients with and those without UTI, we found a considerable degree of overlap between groups, i.e., a low diagnostic accuracy. However, there were significant inverse logarithmic correlations between serum paraoxonase activity and the number of days the urinary catheter had been in situ. Our results suggest that measurement of these biochemical variables may be useful in investigating complications of long-term use of these devices and help to improve the economic and clinical investment required in the management of the often-associated infection.

Pre- and postnatal exposure to tobacco smoke and respiratory outcomes during the first year.

The different role of prenatal and postnatal exposure to tobacco smoke in respiratory outcomes in infants has not yet been clearly established. Our objective is to assess the effects of these exposures on the risk of respiratory outcomes during the first year of life of infants from a Spanish multicenter cohort study. A total of 2506 women were monitored until delivery. About 2039 infants made up the final population. The outcomes were caused by the occurrence of the following: otitis, cough persisting for more than 3 weeks, lower respiratory tract symptoms (wheezing or chestiness), and lower respiratory tract infections (bronchitis, bronchiolitis, or pneumonia). The relationship between prenatal and postnatal exposure and health outcomes was explored using logistic regression analysis. Maternal smoking during pregnancy increased the odds for wheezing (OR: 1.41, 95% CI: 0.99-2.01) and chestiness (OR: 1.46, 95% CI: 1.03-2.01). Postnatal exposure from fathers was associated with otitis (OR: 1.25, 95% CI: 1.01-1.54). Passive exposure at work of non-smoking mothers during pregnancy was related to cough (OR: 1.62, 95% CI: 1.05-2.51). Exposure to tobacco smoke was related to a higher risk of experiencing respiratory outcomes in young infants. Prenatal exposure was that most clearly associated with the respiratory outcomes analyzed.

Evaluation of lens absorbed dose with Cone Beam IGRT procedures.

The purpose of this work is to evaluate the absorbed dose to the eye lenses due to the cone beam computed tomography (CBCT) system used to accurately position the patient during head-and-neck image guided procedures. The on-board imaging (OBI) systems (v.1.5) of Clinac iX and TrueBeam (Varian) accelerators were used to evaluate the imparted dose to the eye lenses and some additional points of the head. All CBCT scans were acquired with the Standard-Dose Head protocol from Varian. Doses were measured using thermoluminescence dosimeters (TLDs) placed in an anthropomorphic phantom. TLDs were calibrated at the beam quality used to reduce their energy dependence. Average dose to the lens due to the OBI systems of the Clinac iX and the TrueBeam were 0.71 ± 0.07 mGy/CBCT and 0.70 ± 0.08 mGy/CBCT, respectively. The extra absorbed dose received by the eye lenses due to one CBCT acquisition with the studied protocol is far below the 500 mGy threshold established by ICRP for cataract formation (ICRP 2011 Statement on Tissue Reactions). However, the incremental effect of several CBCT acquisitions during the whole treatment should be taken into account.

Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities.

In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for (192)Ir and (60)Co HDR applications to account for several different bunker layouts.For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by (192)Ir and (60)Co will reduce the lead thickness by a factor of five for (192)Ir and ten for (60)Co. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers.The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness.

Demonstration of event position reconstruction based on diffusion in the NEXT-white detector.

Noble element time projection chambers are a leading technology for rare event detection in physics, such as for dark matter and neutrinoless double beta decay searches. Time projection chambers typically assign event position in the drift direction using the relative timing of prompt scintillation and delayed charge collection signals, allowing for reconstruction of an absolute position in the drift direction. In this paper, alternate methods for assigning event drift distance via quantification of electron diffusion in a pure high pressure xenon gas time projection chamber are explored. Data from the NEXT-White detector demonstrate the ability to achieve good position assignment accuracy for both high- and low-energy events. Using point-like energy deposits from 83mKr calibration electron captures (E∼45 keV), the position of origin of low-energy events is determined to 2 cm precision with bias <1mm. A convolutional neural network approach is then used to quantify diffusion for longer tracks (E≥1.5 MeV), from radiogenic electrons, yielding a precision of 3 cm on the event barycenter. The precision achieved with these methods indicates the feasibility energy calibrations of better than 1% FWHM at Qßß in pure xenon, as well as the potential for event fiducialization in large future detectors using an alternate method that does not rely on primary scintillation.

Meconium microbiota types dominated by lactic acid or enteric bacteria are differentially associated with maternal eczema and respiratory problems in infants.

BACKGROUND: Culture-dependent methods have shown that meconium, the newborn's first intestinal discharge, is not sterile, but the diversity of bacteria present in this material needs to be further characterized by means of more sensitive molecular techniques. OBJECTIVE: Our aims were to characterize molecularly the meconium microbiota in term infants, to assess whether it contributes to the future microbiota of the infants' gastrointestinal tract, and to evaluate how it relates to lifestyle variables and atopy-related conditions. METHODS: We applied high-throughput pyrosequencing of the 16S rRNA gene to study the meconium microbiota in twenty term newborns from a Spanish birth cohort. For comparison, we characterized the microbiota in fecal samples from seven pregnant women days before delivery and in two series of infant samples spanning the first seven months of life. We also compared our data with vaginal and skin microbiota characterized in independent studies. Different types of meconium microbiota were defined based on taxonomic composition and abundance and their associations with different factors were statistically evaluated. RESULTS: The meconium microbiota differs from those in adult feces, vagina and skin, but resembles that of fecal samples from young infants. Meconium samples clustered into two types with different bacterial diversity, richness and composition. One of the types was less diverse, dominated by enteric bacteria and associated with a history of atopic eczema in the mother (P = 0.038), whereas the second type was dominated by lactic acid bacteria and associated with respiratory problems in the infant (P = 0.040). CONCLUSIONS & CLINICAL RELEVANCE: Our findings suggest that the meconium microbiota has an intrauterine origin and participates in gut colonization. Although based on a small population sample, our association analyses also suggest that the type of bacteria detected in meconium is influenced by maternal factors and may have consequences for childhood health.

Severe chronic allergic (and related) diseases: a uniform approach--a MeDALL--GA2LEN--ARIA position paper.

Concepts of disease severity, activity, control and responsiveness to treatment are linked but different. Severity refers to the loss of function of the organs induced by the disease process or to the occurrence of severe acute exacerbations. Severity may vary over time and needs regular follow-up. Control is the degree to which therapy goals are currently met. These concepts have evolved over time for asthma in guidelines, task forces or consensus meetings. The aim of this paper is to generalize the approach of the uniform definition of severe asthma presented to WHO for chronic allergic and associated diseases (rhinitis, chronic rhinosinusitis, chronic urticaria and atopic dermatitis) in order to have a uniform definition of severity, control and risk, usable in most situations. It is based on the appropriate diagnosis, availability and accessibility of treatments, treatment responsiveness and associated factors such as comorbidities and risk factors. This uniform definition will allow a better definition of the phenotypes of severe allergic (and related) diseases for clinical practice, research (including epidemiology), public health purposes, education and the discovery of novel therapies.

Influence of fetal glutathione S-transferase copy number variants on adverse reproductive outcomes.

A nested case-control association study was designed to investigate the influence of maternal and fetal copy number variants (CNVs) on reproductive outcomes. Genotypes of ten CNVs encompassing GST and CYP genes were assessed. Significant associations were only found for child CNV genotypes. In particular, the child GSTM1 insertion allele was associated with prematurity protection (odds ratio, 95% CI: 0.67, 0.51-0.89; P < 0.01), whereas the child GSTT2B insertion allele was associated with an increased risk of being small for gestational age (odds ratio, 95% CI: 1.33, 1.07-1.67; P = 0.01). The study highlights the role of the fetal genome in prenatal development and also the need to analyse CNVs in a systematic manner.

MeDALL (Mechanisms of the Development of ALLergy): an integrated approach from phenotypes to systems medicine.

The origin of the epidemic of IgE-associated (allergic) diseases is unclear. MeDALL (Mechanisms of the Development of ALLergy), an FP7 European Union project (No. 264357), aims to generate novel knowledge on the mechanisms of initiation of allergy and to propose early diagnosis, prevention, and targets for therapy. A novel phenotype definition and an integrative translational approach are needed to understand how a network of molecular and environmental factors can lead to complex allergic diseases. A novel, stepwise, large-scale, and integrative approach will be led by a network of complementary experts in allergy, epidemiology, allergen biochemistry, immunology, molecular biology, epigenetics, functional genomics, bioinformatics, computational and systems biology. The following steps are proposed: (i) Identification of 'classical' and 'novel' phenotypes in existing birth cohorts; (ii) Building discovery of the relevant mechanisms in IgE-associated allergic diseases in existing longitudinal birth cohorts and Karelian children; (iii) Validation and redefinition of classical and novel phenotypes of IgE-associated allergic diseases; and (iv) Translational integration of systems biology outcomes into health care, including societal aspects. MeDALL will lead to: (i) A better understanding of allergic phenotypes, thus expanding current knowledge of the genomic and environmental determinants of allergic diseases in an integrative way; (ii) Novel diagnostic tools for the early diagnosis of allergy, targets for the development of novel treatment modalities, and prevention of allergic diseases; (iii) Improving the health of European citizens as well as increasing the competitiveness and boosting the innovative capacity of Europe, while addressing global health issues and ethical issues.

Magnetic double-J stent: Evaluation of tolerance and impact on quality of life compared to traditional double-J stent.

INTRODUCTION: The placement of a ureteral stent is one of the most widely performed procedures in urology. It can have a negative impact on the patients' quality of life, requiring a cystoscopy for its removal. The objective of this study is to evaluate the symptoms and impact on quality of life derived from the use of a magnetic double-J stent (Black Star®) and compare them to those presented in patients with a traditional double-J stent (OptiMed®). MATERIAL AND METHODS: We conducted a comparative, prospective, randomized study in 46 patients who underwent ureterorenoscopy with double-J stent placement between August 2019 and June 2020. Of all patients included, 23 had a traditional double-J stent placed (group A) and 23 had a magnetic double-J stent (group B) placed. We evaluated the results of the Ureteral Stent Symptom Questionnaire (USSQ) in both groups, assessed the technical difficulty related to stent removal and the pain during the procedure using the Visual Analogue Scale (VAS). We also reviewed the need for medical attention due to problems related to the stent or after its removal. RESULTS: There were no statistically significant differences between groups regarding the answers in the USSQ and the complications related to the use of the stent. Group B showed less pain (1.52 vs. 4, VAS, p = 0.001) and less difficulty during removal (1.61 vs. 3, p < 0.001) associated with a shorter procedure duration (11.65 min vs. 22.17 min p < 0.001). CONCLUSIONS: The tolerance shown by the use of magnetic double-J is comparable to the tolerance of traditional stent, since it does not cause an increase in urinary symptoms nor worsens the quality of life of patients during its use.

Treatment for rectourethral fistulas after radical prostatectomy with biological material interposition through a perineal access.

INTRODUCTION: Rectal injury is a rare complication after extraperitoneal laparoscopic radical prostatectomy. The development of rectourethral fistulas (URF) from rectal injuries is one of the most feared and of more complex resolution in urology. MATERIAL AND METHODS: Between 2013 and 2020 we have operated on a total of 5 patients with URF after extraperitoneal endoscopic radical prostatectomy through a perineal access using the interposition of biological material. All fistulas had a diameter of less than 6 mm at endoscopy and were less than 6 cm apart from the anal margin. RESULTS: The mean age of the patients was 64 years old. All patients had a previous bowel and urinary diversion for at least 3 months. Under general anesthesia and with the patient in a forced lithotomy position, fistulorraphy and interposition of biological material of porcine origin (lyophilized porcine dermis [Permacol®]) were performed through a perineal access. Mean operative time was 174 min (140-210). Most patients were discharged on the third postoperative day. The bladder catheter was left in place for a mean of 40 days (30-60). Prior to its removal, cystography and a Gastrografin® barium enema were performed, showing resolution of the fistula in all cases. CONCLUSIONS: The interposition of biological material from porcine dermis through perineal approach is a safe alternative with good results in patients submitted to urethrorectal fistulorraphy after radical prostatectomy.

Indoor and outdoor concentrations and determinants of NO2 in a cohort of 1-year-old children in Valencia, Spain.

UNLABELLED: Nitrogen dioxide (NO2) is produced from the exhausts of vehicles and gas appliances and is known to pose certain health risks. In this study, we characterize the exposure to this substance during the first year of life, which is an important period of development. To this end, we used passive samplers to measure indoor and outdoor NO2 levels for 2 weeks in the homes of 352 children. To compensate for the fact that NO2 levels were measured only once in each home, a correction factor was calculated to assign each child an outdoor NO2 exposure value for the first year of life. The outdoor NO2 concentrations were 26.1 microg/m(3) while those measured indoors averaged 18.0 microg/m(3). A multivariate linear regression analysis showed that the main determinants of outdoor NO2 levels were the degree of urbanization and the frequency of vehicle traffic at the location of the residence while for indoor NO2 levels the principal determinants were the type of cooking range and water heater present in the home, the season of the year, and both the country of origin and educational level of the mother. PRACTICAL IMPLICATIONS: Exposure to NO2 has been related to respiratory and other health problems among children. Precise identification of the main sources of both indoor and outdoor NO2 should shed light on appropriate intervention periods and methods. Our results indicate that while population density and traffic-related variables are the main determinants of outdoor NO2 levels, the use of gas appliances have the greatest impact on indoor levels. Strategies should thus be developed to reduce such exposure, especially with regard to reducing emissions from vehicle traffic.

Determination of consensus k Q values for megavoltage photon beams for the update of IAEA TRS-398.

The IAEA is currently coordinating a multi-year project to update the TRS-398 Code of Practice for the dosimetry of external beam radiotherapy based on standards of absorbed dose to water. One major aspect of the project is the determination of new beam quality correction factors, k Q , for megavoltage photon beams consistent with developments in radiotherapy dosimetry and technology since the publication of TRS-398 in 2000. Specifically, all values must be based on, or consistent with, the key data of ICRU Report 90. Data sets obtained from Monte Carlo (MC) calculations by advanced users and measurements at primary standards laboratories have been compiled for 23 cylindrical ionization chamber types, consisting of 725 MC-calculated and 179 experimental data points. These have been used to derive consensus k Q values as a function of the beam quality index TPR20,10 with a combined standard uncertainty of 0.6%. Mean values of MC-derived chamber-specific [Formula: see text] factors for cylindrical and plane-parallel chamber types in 60Co beams have also been obtained with an estimated uncertainty of 0.4%.

Epidemiology of appendectomy and appendicitis in the Valencian community (Spain), 1998-2007.

BACKGROUND/AIMS: Our purpose was to study the incidence of appendectomy and appendicitis in the Valencian community (Spain) during a period of 10 years (1998-2007). METHODS: Data on discharge diagnoses of appendectomy and appendicitis were downloaded from all public hospitals in the Valencian community. RESULTS: We identified 44,683 cases of appendectomies and 42,742 cases of appendicitis (95.7%) during the study period. The age-standardized incidence rates among men ranked between 132.1 cases per 100,000 population in 2003 and 117.46 cases per 100,000 population in 2000 without a clear trend through the study period. The appendiceal perforation rate was 12.1% and the negative appendectomy rate 4.3%. The global mortality was 0.38%. CONCLUSIONS: The incidence of appendectomy in our community presents a slight descending trend. This decline is more intense in females. The appendix perforation rate is lower than in other studies. The death rate is similar to other studies; however, it is very low in patients of younger age.

Effects of cold weather on mortality: results from 15 European cities within the PHEWE project.

Weather-related health effects have attracted renewed interest because of the observed and predicted climate change. The authors studied the short-term effects of cold weather on mortality in 15 European cities. The effects of minimum apparent temperature on cause- and age-specific daily mortality were assessed for the cold season (October-March) by using data from 1990-2000. For city-specific analysis, the authors used Poisson regression and distributed lag models, controlling for potential confounders. Meta-regression models summarized the results and explored heterogeneity. A 1 degrees C decrease in temperature was associated with a 1.35% (95% confidence interval (CI): 1.16, 1.53) increase in the daily number of total natural deaths and a 1.72% (95% CI: 1.44, 2.01), 3.30% (95% CI: 2.61, 3.99), and 1.25% (95% CI: 0.77, 1.73) increase in cardiovascular, respiratory, and cerebrovascular deaths, respectively. The increase was greater for the older age groups. The cold effect was found to be greater in warmer (southern) cities and persisted up to 23 days, with no evidence of mortality displacement. Cold-related mortality is an important public health problem across Europe. It should not be underestimated by public health authorities because of the recent focus on heat-wave episodes.