Incident air kerma to absorbed organ dose conversion factors for breast and lung in PA thorax radiography: The effect of patient thickness and radiation quality

PurposeConverting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined.MethodsIn this study, the posterior–anterior projection radiograph of the thorax was selected in order to determine the effect of radiation quality (tube voltages of 70–130 kV and total filtrations of 3 mmAl to 4 mmAl + 0.2 mmCu) and patient thickness (anterior–posterior thicknesses of 19.4–30.8 cm) on the breast and lung dose conversion factors. For this purpose, Monte Carlo simulation programs ImpactMC and PCXMC were used with computed tomography examination data of adult male and female patients and mathematical hermaphrodite phantoms, respectively.ResultsCompared to the reference beam quality and patient thickness, the relative variation range in organ dose conversion factors was up to 74% for different radiation qualities and 122% for different patient thicknesses.ConclusionsConversion factors should only be used with comprehensive understanding of the exposure conditions, considering the exposure parameters, exposure geometry and patient anatomy they are valid for. This study demonstrates that patient thickness-specific and radiation quality-specific conversion factors are needed in projection radiography.     

Two populations of TSPO binding sites in oral cancer SCC-15 cells

Oral cancer mortality and morbidity rates remain high. The main inducer of oral cancer is cigarette smoke (CS). Translocator protein 18 kDa (TSPO) was shown to play a role in carcinogenesis. We characterized TSPO binding sites in human oral cancer cell line SCC-15 and examined effect of CS on TSPO binding. We exposed SCC-15 human squamous cells to cigarette smoke. [³H]PK 11195 binding results were assessed in cells confluent for one day. To characterize the number of population sites, a custom written Matlab program compared Pearson linear correlation coefficients between all points in the Scatchard plot. Using [³H]PK 11195 as a radio ligand, we found that TSPO binding sites are not uniform, but separated into two sub-populations, one with high affinity (respective Kd and Bmax values of 1.40±0.08 nM and 1586±48 fmol/mg protein), another with lower affinity (respective Kd and Bmax values of 61±5 nM and 26260±1050 fmol/mg protein). We demonstrate rapid decrease in TSPO binding to the high affinity site induced by exposure to CS; specifically, significant 36% decrease in binding after 30 min CS exposure (p<0.05), and 69% decrease after 2 h CS exposure (p<0.05). Association between TSPO and CS exposure may contribute to understanding the underlying mechanism of oral carcinogenesis.     

Influence of beam incidence and irradiation parameters on stray neutron doses to healthy organs of pediatric patients treated for an intracranial tumor with passive scattering proton therapy

PurposeIn scattering proton therapy, the beam incidence, i.e. the patient’s orientation with respect to the beam axis, can significantly influence stray neutron doses although it is almost not documented in the literature.MethodsMCNPX calculations were carried out to estimate stray neutron doses to 25 healthy organs of a 10-year-old female phantom treated for an intracranial tumor. Two beam incidences were considered in this article, namely a superior (SUP) field and a right lateral (RLAT) field. For both fields, a parametric study was performed varying proton beam energy, modulation width, collimator aperture and thickness, compensator thickness and air gap size.ResultsUsing a standard beam line configuration for a craniopharyngioma treatment, neutron absorbed doses per therapeutic dose of 63 μGy Gy⁻¹ and 149 μGy Gy⁻¹ were found at the heart for the SUP and the RLAT fields, respectively. This dose discrepancy was explained by the different patient’s orientations leading to changes in the distance between organs and the final collimator where external neutrons are mainly produced. Moreover, investigations on neutron spectral fluence at the heart showed that the number of neutrons was 2.5 times higher for the RLAT field compared against the SUP field. Finally, the influence of some irradiation parameters on neutron doses was found to be different according to the beam incidence.ConclusionBeam incidence was thus found to induce large variations in stray neutron doses, proving that this parameter could be optimized to enhance the radiation protection of the patient.     

Interaction of exposure concentration and duration in determining the apoptosis of testis in rats after cigarette smoke inhalation

The effects of differences in smoke concentration and exposure duration in Sprague Dawley rats to determine variation in type and severity of the testis apoptosis were evaluated. The daily dosages were 10, 20 and 30 non-filter cigarettes for a period of 2, 4, 6, 8 and 12 weeks. Mainstream smoke exposure suppressed body weight gain in all regimens. A dose-related increase in plasma nicotine concentration was observed in smoke-exposed groups for 4, 6, 8 and 12 week regimens. Histopathological examination of the exposed groups showed disturbances in the stages of spermatogenesis, tubules atrophying and these appeared to be dose-related. Cytoplasmic caspase-3 immunostaining was detected both in Sertoli cells and germ cells in smoke-exposure groups. An increase in TUNEL-positive cells of testicular cells was observed after 6 weeks of cigarette exposure. The results indicate that cigarette exposure concentration and duration have interaction effect to induce apoptosis in the rat testes.     

Blood lead and cadmium levels in a six hospital employee population. PESA study, 2009

IntroductionExposure to lead and cadmium is a public health problem due to the broad exposure to these toxic substances among the general population. The objective of this study is to determine blood lead and cadmium concentrations in a working population drawn from six university hospitals in Madrid, Getafe, Cartagena, Santiago de Compostela, Santander and Palma de Mallorca (Spain) and to identify associated factors.Materials and methods951 individuals participated in the study and were administered the standardized PESA^® questionnaire regarding exposure to lead and cadmium. The blood lead and cadmium concentrations were measured by electrothermal atomization atomic absorption spectrometry with Zeeman background correction in Perkin-Elmer spectrometers, guaranteeing the transferability of the results.ResultsThe median overall blood lead concentration was: 1.6 μg/dL (IQR: 0.9–2.7) and that of cadmium was: 0.21 μg/L (IQR: 0.10–0.50). There were significant differences in lead levels between men (2 μg/dL) and women (1.5 μg/dL), postmenopausal (2.6 μg/dL) and premenopausal women (1.1 μg/dL), and between participants who cooked in earthenware (2.1 μg/dL) and those who did not (1.5 μg/dL). The median of cadmium in women (0.24 μg/L) was higher than in men (0.11 μg/L) and was also higher in subjects who smoked (0.70 μg/L) than in non-smokers (0.13 μg/L).ConclusionsA reduction in blood lead and cadmium levels was observed with respect to previous studies carried out in Spain. Nevertheless, the results suggest there are certain factors which increase risk such as age, gender, menopause, age of housing, cooking in lead-glazed earthenware and exposure to cigarette smoke.     

Low concentrations of methamidophos do not alter AChE activity but modulate neurotransmitters uptake in hippocampus and striatum in vitro

AimsMethamidophos (Meth) is a toxic organophosphorus compound (OP) that inhibits acetylcholinesterase enzyme (AChE) and induces neurotoxicity. As the mechanism of its neurotoxic effects is not well understood, the aim of the present study was to evaluate the effects of Meth on glutamate and gamma aminobutyric acid (GABA) uptake and correlate with cell viability and AChE and Na⁺/K⁺-ATPase enzyme activities in striatum and hippocampus slices exposed to low concentrations (0.05 to 1.0 μM) of Meth.Main methodsHippocampal and striatal slices of rat brain were exposed to Meth for 5 min ([³H]Glutamate uptake) or 15 min ([³H]GABA uptake) for assays. The enzyme activities and cell viability were also accessed at both times in hippocampal and striatal slices and homogenates.Key findingsAt concentrations that did not inhibit AChE, Meth caused changes in glutamate uptake in striatal (0.05 and 1.0 μM Meth) and hippocampal (1.0 μM Meth) slices. GABA uptake was increased by the pesticide in striatum at 0.5 and 1.0 μM and in hippocampus at 0.05 μM. After 3.5 h of Meth exposure, striatal and hippocampal cells showed no changes in viability as well as no inhibition of Na⁺/K⁺-ATPase were observed after 5 or 15 min exposure to Meth in the same brain structures.SignificanceResults suggest that Meth, even without changing the AChE activity can modify somehow the neurotransmitters uptake. However, further studies are necessary to clarify if this modulation in glutamate or GABA uptake may be responsible to cause some disturbance in behavior or in other neurochemical parameters following low Meth exposure in vivo.     

Deformation and recovery of cartilage in the intact hip under physiological loads using 7 T MRI

Accurate measurement of cartilage deformation in loaded cadaver hip joints could be a valuable tool to answer clinically relevant research questions. MRI is a promising tool, but its use requires an understanding of cartilage deformation and recovery properties in the intact hip. Our objective was to answer the following questions: (1) How long does it take for hip cartilage to reach a deformed steady-state thickness distribution under simulated physiological load, and how much does the cartilage deform? (2) How long does it take for hip cartilage to return to the original cartilage thickness distribution once the load is removed?MethodsFive human hip specimens were axially loaded to 1980 N in a 7 T MR scanner and scanned every 15 min throughout loading. One specimen was scanned every hour throughout recovery from load. One repeatability specimen was loaded and scanned every day for 4 days. Hip cartilage was segmented as a single unit and thickness was measured radially.ResultsThe hip cartilage reached a steady-state thickness distribution after 225 min of load, and 16.5 h of recovery. Mean strain after 225 min of load was 30.9%. The repeatability specimen showed an average day-to-day change in mean cartilage thickness of 0.10 mm over 4 days of data collection. The amount of deformation (0.96 mm) was far greater than the image resolution (0.11 mm) and error due to repeatability (0.10 mm).ConclusionUsing an ex vivo model, this method has potential for assessing changes in hip cartilage strain due to injury or surgical intervention.     

Performances diagnostiques des tomoscintigraphies myocardiques de stress,réalisées avec une caméra à semi-conducteurs et un protocole très faible dose

IntroductionThis retrospective study aimed to assess the performances in the detection of coronary artery disease patients of the stress myocardial perfusion imaging (MPI) performed with a semiconductor camera, a very low dose stress-rest protocol and short recording times.Material and methodsWe analyzed consecutive MPI exams, which has been routinely planed with the “D-SPECT” semiconductor camera, a 1-day stress-rest protocol, very low doses of Sestamibi-^99mTc (120 MBq at stress and 360 MBq at rest for a 75 kg body weight patient) and short acquisition-times targeting the recording of 500 myocardial kcounts (on average, 8 min for stress and 3 min for rest). The ability to detect coronary artery stenosis (> 50% diameter reduction) was assessed in a group of 118 patients, who had coronary angiography at ≤ 3 months from MPI, and normalcy rate was assessed in a group of 74 patients showing a low pretest probability of coronary artery disease (< 10%).ResultsSensitivity, positive predictive value and global accuracy for identifying the 81 patients with ≥ 1 coronary artery stenosis were 85%, 83% and 78%, respectively; and normalcy rate was 96%. Mean effective doses were: (1) 4.9 ± 1.4 mSv in the group with coronary angiography and where most exams (90%) comprised both stress and rest MPI; and (2) 1.9 ± 1.5 mSv in the low probability group and where most exams (70%) comprised only stress MPI.ConclusionWhen performed with a sensitive semiconductor camera and a very low dose stress-rest protocol, MPI provides high diagnostic performances, equivalent to those documented with conventional cameras in the same study setting, but with dramatic reduction of patients’ radiation.     

A comparison of a moderately hypofractionated IMRT planning technique used in a randomised UK external beam radiotherapy trial with an in-house technique for localised prostate cancer

AimTo compare the radiotherapy technique used in a randomised trial with VMAT and an in-house technique for prostate cancer.BackgroundTechniques are evolving with volumetric modulated arc therapy (VMAT) commonly used. The CHHiP trial used a 3 PTV forward planned IMRT technique (FP_CH). Our centre has adopted a simpler two PTV technique with locally calculated margins.Materials and methods25 patients treated with FP_CH to 60 Gy in 20 fractions were re-planned with VMAT (VMAT_CH) and a two PTV protocol (VMAT_60/52 and VMAT_60/48). Target coverage, conformity index (CI), homogeneity index (HI), monitor units (MU) and dose to the rectum, bladder, hips and penile bulb were compared.ResultsPTV coverage was high for all techniques. VMAT_CH plans had better CI than FP_CH (p ≤  0.05). VMAT_60/52/48 plans had better CI than VMAT_CH. FP_CH had better HI and fewer MU than VMAT (p ≤  0.05). More favourable rectum doses were found for VMAT _CH than FP_CH (V_48.6, V_52.8, V₅₇, p ≤  0.05) with less difference for bladder (p ≥  0.05). Comparing VMAT_CH to VMAT_60/52/48 showed little differences for the bladder and rectum but VMAT_CH had larger penile bulb doses (V_40.8, V_48.6, mean, D_2, p ≤  0.05). Femoral head doses (V_40.8) were similarly low for all techniques (p = ≥ 0.05).ConclusionVMAT produced more conformal plans with smaller rectum doses compared to FP_CH albeit worse HI and more MU. VMAT_60/52 and VMAT_60/48 plans had similar rectal and bladder doses to VMAT_CH but better CI and penile bulb doses which may reduce toxicity.     

Comparison between hepatic and renal effects in rats treated with arsenic and/or antioxidants during gestation and lactation

The aim of this study was to determine whether biochemical changes occurred in the liver and kidney of arsenic (As) exposed pups during gestation and lactation, and investigate the potential beneficial role of antioxidants against arsenic exposure damage. Pregnant wistar rats received the following treatments as drinking water: (1) distilled water; (2) arsenic (50 mg/L); (3) antioxidants: zinc (20 mg/L) + vitamin C (2 g/L) + vitamin E (500 mg/L); (4) arsenic (50 mg/L) + antioxidants. As- intoxicated pups showed significant decreases in liver cholesterol and triglyceride concentration, whereas Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were increased. Treatment with antioxidants returns these values to control ones. TBARS production in both organs and liver glutathione peroxidase (GPx) activity also increased whereas catalase (CAT) activity in both organs decreased in arsenic-exposed pups; the antioxidant administration only recover TBARS concentration to control values. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of arsenic.     

Assessment of salivary cotinine concentration among general non-smokers population: Before and after Spanish smoking legislations

BackgroundIn Spain, two smoke-free laws have been passed (Law 28/2005 and Law 42/2010).This study evaluates the association between Spanish smoking legislations and the second-hand smoke (SHS) exposure in an adult non-smoking population cohort in Barcelona (Spain).MethodsThis is a longitudinal study, before and after the implementation of two national smoking bans, in a representative sample of adults (≥16 years old) from Barcelona (Spain) surveyed in 2004–2005 and followed up in 2013–2014 (n = 736). We only analyzed non-smokers (n = 397). We obtained 9 ml of saliva sample for analysis of cotinine, a biomarker of recent tobacco exposure. We calculated geometric means of salivary cotinine concentration and their geometric standard deviation. We used linear mixed effect models, with individuals as random effects, to model the percentage change in salivary cotinine concentration and their 95% confidence intervals.ResultsThe percentage of participants with saliva samples with measurable concentrations of cotinine fell from 92.4% to 64.2% after both Spanish smoking legislations. The geometric mean of salivary cotinine concentration significantly decreased 88% (from 0.98 ng/mL to 0.12 ng/mL, p < 0.001) after the implementation of the two Spanish smoke-free legislations. The decrease of the GM salivary cotinine concentration was statistically significant independently of the sociodemographic variables.ConclusionThere was a large reduction in the salivary cotinine concentration among adult non-smokers and higher cotinine concentrations among those declaring exposure to SHS at home after both legislations. Moreover, after both Spanish smoke-free laws salivary cotinine concentration was homogenized according to sociodemographic variables.     

Repeat estradiol exposure differentially regulates protein expression patterns for estrogen receptor and E-cadherin in older mouse ovarian surface epithelium: Implications for replacement and adjuvant hormone therapies?

BackgroundEstrogen replacement therapy increases risk for ovarian epithelial cancer, a cancer of mainly older women, yet the response of older ovarian surface epithelium (OSE) to repeat estrogen exposure overtime has not been studied. We have previously reported significant reductions in estrogen receptor (ER) protein expression, particularly the ERβ1 isoform, in older mouse OSE following a single depot estradiol injection. The current study examined OSE from older mice following a single, and repeat estradiol injection, given 14 days apart over 28 days.MethodsCohorts of mice were sacrificed 48 hours following each estradiol injection, and at three other equidistant time points. Serum and ovarian tissue estradiol concentration was correlated to immunohistochemical and morphometric parameters used to identify evidence of OSE hyperplasia and hypertrophy. Using immunohistochemistry, E-cadherin expression was investigated in OSE 48 hours following both estradiol injections, while ERα and ERβ1 expression was examined in OSE following repeat estradiol exposure only.ResultsFirst exposure to exogenous estradiol resulted in OSE hypertrophy and hyperplasia, and high levels of E-cadherin expression. In contrast, repeat estradiol exposure resulted in no OSE hyperplasia or hypertrophy, low levels of E-cadherin expression, high ERα and reduced ERβ1 protein expression in OSE, and low stromal ERα expression. Blood and ovarian tissue estradiol levels following repeat estradiol injection were half those recorded after a first dose equivalent injection, but remained significantly elevated above controls.ConclusionRepeat estradiol exposure leads to accumulation of estradiol in ovarian tissue, differentially regulating protein expression patterns for E-cadherin in OSE and ER in OSE and stroma.     

Telomere susceptibility to cigarette smoke-induced oxidative damage and chromosomal instability of mouse embryos in vitro

Cigarette smoke is associated with high risk of lung, cardiovascular, and degenerative diseases, reduced fertility, and possibly the health of newborns. Cigarette smoke contains many components and exerts its genotoxicity in part by generating reactive oxidative stress. Telomeres consist of repeated ‘G’ rich sequences and associated proteins located at the chromosomal ends that maintain chromosomal integrity. We tested the hypothesis that telomere shortening and dysfunction are implicated in smoke associated oxidative damage and chromosomal instability using early mouse embryos in vitro and short-telomere mouse model. Mouse embryos exposed to smoke components, cigarette smoke condensate (CSC) at the concentration of 0.02 mg/ml continuously or 0.1 mg/ml for 20 h, or cadmium at 5-100 µM, exhibited increased oxidative stress and telomere shortening and loss, associated with chromosomal instability, apoptosis, and compromised embryo cleavage and development. Remarkably, reduction of oxidative stress by an antioxidant N-acetyl-L-cysteine (NAC) greatly reduced these toxicities. Notably, cadmium led to more severe oxidative damage and telomere dysfunction, which could be more effectively rescued by antioxidant treatment, than did CSC. Moreover, short telomeres predisposed embryos to smoke component-induced oxidative damage. These data further extend our understanding of mechanisms underlying smoke-induced oxidative damage to include telomere dysfunction and chromosomal instability.     

Dietary coenzyme Q10 does not protect against cigarette smoke-augmented atherosclerosis in apoE-deficient mice

Dietary coenzyme Q10 reduces spontaneous atherosclerosis in the apoE-deficient mouse model of experimental atherosclerosis. We have shown previously that exposure to sidestream cigarette smoke (SSCS) enhances atherosclerotic lesion formation in apoE-deficient mice. The aim of the present study was to determine if CoQ10 protected against SSCS-mediated atherosclerosis. Female apoE-deficient mice were fed a saturated fat-enriched diet (SFD) alone, or supplemented with 1% wt/wt coenzyme Q10 (SFD-Q10). Mice in each diet group were exposed to SSCS for 4 hrs/day, 5 days/week in a whole-body exposure chamber maintained at 35 ± 4 mg smoke particulates/m³. Mice kept in filtered ambient air served as controls. Mice were euthanized after either 6 or 15 weeks of SSCS exposure and following measurements were performed: i) lung 7-ethoxyresorufin-O-deethylase (EROD) activity; ii) plasma cholesterol and CoQ10 concentrations; iii) aortic intimal area covered by atherosclerotic lesions; and, iv) pathological characterization of lesions. Lung EROD activity increased in SSCS mice of both diet groups, confirming SSCS exposure. Plasma concentrations of CoQ10 in SFD-Q10-fed mice were increased markedly in comparison to SFD-fed mice. Plasma cholesterol concentrations and distributions of cholesterol in lipoprotein fractions were unaffected by SSCS exposure. Dietary supplementation with CoQ10 significantly reduced atherosclerotic lesions in control mice. As reported previously, exposure to SSCS increased the size of lesions in apoE-/- mice at both time points. However, dietary supplementation with CoQ10 had no effect on atherosclerotic lesions augmented by SSCS exposure. The results suggest a role of oxidative processes in smoke-augmented atherosclerosis that are different than those mitigated by CoQ10.     

Sperm viability and gene expression in honey bee queens (Apis mellifera) following exposure to the neonicotinoid insecticide imidacloprid and the organophosphate acaricide coumaphos

Honey bee population declines are of global concern. Numerous factors appear to cause these declines including parasites, pathogens, malnutrition and pesticides. Residues of the organophosphate acaricide coumaphos and the neonicotinoid insecticide imidacloprid, widely used to combat Varroa mites and for crop protection in agriculture, respectively, have been detected in wax, pollen and comb samples. Here, we assess the effects of these compounds at different doses on the viability of sperm stored in the honey bee queens’ spermatheca. Our results demonstrate that sub-lethal doses of imidacloprid (0.02 ppm) decreased sperm viability by 50%, 7 days after treatment. Sperm viability was a downward trend (about 33%) in queens treated with high doses of coumaphos (100 ppm), but there was not significant difference. The expression of genes that are involved in development, immune responses and detoxification in honey bee queens and workers exposed to chemicals was measured by qPCR analysis. The data showed that expression levels of specific genes were triggered 1 day after treatment. The expression levels of P450 subfamily genes, CYP306A1, CYP4G11 and CYP6AS14 were decreased in honey bee queens treated with low doses of coumaphos (5 ppm) and imidacloprid (0.02 ppm). Moreover, these two compounds suppressed the expression of genes related to antioxidation, immunity and development in queens at day 1. Up-regulation of antioxidants by these compounds in worker bees was observed at day 1. Coumaphos also caused a repression of CYP306A1 and CYP4G11 in workers. Antioxidants appear to prevent chemical damage to honey bees. We also found that DWV replication increased in workers treated with imidacloprid. This research clearly demonstrates that chemical exposure can affect sperm viability in queen honey bees.     

Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit

Objective

Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit.

Cyto-genotoxic effects of smoke from commercial filter and non-filter cigarettes on human bronchial and pulmonary cells

Cigarette smoke is a complex mixture of chemicals, some of which are known as carcinogens. The cyto-genotoxic effects of cigarette-smoke extract (CSE) from commercial cigarettes without (A and B) and with filter (C and D) were evaluated at different CSE concentrations on A549 and BEAS-2B cells. The particle content of the cigarette smoke and the metal composition of the CSE were also analyzed. The cells were exposed to 1–10% of the CSE from one cigarette per experiment. Cytotoxicity was evaluated by use of the MTT assay after 24 h, and the lactate dehydrogenase (LDH) assay after 30 min and 24 h. The Fpg-modified comet assay was used to evaluate direct-oxidative DNA damage on cells exposed for 30 min. As expected, unfiltered cigarette smoke (particularly from the B cigarette) contained a higher number of particles than filtered smoke. With smoke extract from the B cigarette we found a decrease in cell viability only in BEAS-2B cells. The results of the LDH test showed membrane damage for B-cigarette smoke extract, particularly in BEAS-2B cells. Extracts from unfiltered cigarette smoke induced significant direct DNA damage, to a larger extent in A549 cells. Filtered cigarette-smoke extract induced a significant direct DNA damage at 5–10%. A significant induction of oxidative DNA damage was found at the highest CSE concentration in both cell types (by smoke extracts from B and C cigarettes in A549 cells, and from A and D cigarettes in BEAS-2B cells). Smoke extracts from filter cigarettes induced less direct DNA damage than those from unfiltered cigarettes in A549 cells, probably due to a protective effect of filter. In BEAS-2B cells the smoke extract from the B-cigarette showed the highest genotoxic effect, with a concentration-dependent trend.These findings show a higher cyto-genotoxicity for smoke extracts from the B-cigarette and oxidative effects for those from the A and D cigarettes, particularly in BEAS-2B cells. Moreover, there was a higher responsiveness of A549 cells to genotoxic insult of CSE, and a cigarette-dependent genotoxicity in BEAS-2B cells. Our experimental model demonstrated to be suitable to sensitively detect early genotoxic response of different lung-cell types to non-cytotoxic concentrations of complex inhalable mixtures.     

A novel position-sensitive mega-size dosimeter for photoneutrons in high-energy X-ray medical accelerators

PurposeA novel position-sensitive mega-size polycarbonate (MSPC) dosimeter is introduced. It provides photoneutron (PN) dose equivalent matrix of positions in and out of a beam of a high energy X-ray medical accelerator under a single exposure.MethodsA novel position-sensitive MSPC dosimeter was developed and applied. It has an effective etched area of 50 × 50 cm², as used in this study, processed in a mega-size electrochemical etching chamber to amplify PN-induced-recoil tracks to a point viewed by the unaided eyes. Using such dosimeters, PN dose equivalents, dose equivalent profiles and isodose equivalent distribution of positions in and out of beams for different X-ray doses and field sizes were determined in a Siemens ONCOR Linac.ResultsThe PN dose equivalent at each position versus X-ray dose was linear up to 20 Gy studied. As the field size increased, the PN dose equivalent in the beam was also increased but it remained constant at positions out of the beam up to 20 cm away from the beam edge. The jaws and MLCs due to material differences and locations relative to the target produce different PN contributions.ConclusionsThe MSPC dosimeter introduced in this study is a perfect candidate for PN dosimetry with unique characteristics such as simplicity, efficiency, dose equivalent response, large size, flexibility to be bent, resembling the patient’s skin, highly position-sensitive with high spatial resolution, highly insensitive to X-rays, continuity in measurements and need to a single dosimeter to obtain PN dose equivalent matrix data under a single X-ray exposure.     

Risk of neuroblastoma,maternal characteristics and perinatal exposures: The SETIL study

PurposeNeuroblastoma (NB) is the most common extra-cranial paediatric solid tumour. Incidence peaks in infancy, suggesting a role of in-utero and neonatal exposures but its aetiology is largely unknown. The aim of the present study is to evaluate the association between maternal characteristics and perinatal factors with the risk of NB, using data from the SETIL database.MethodsSETIL is a large Italian population-based case-control study established to evaluate several potential cancer risk factors in 0–10 year olds. Information about maternal characteristics, reproductive history, environmental and occupational exposures during pregnancy, as well as newborns’ characteristics were obtained using a structured questionnaire. Extremely low frequency magnetic field (ELF-MF) home exposure was measured. The study included 1044 healthy controls and 153 NB cases, diagnosed between 1998 and 2001.ResultsA twofold risk was associated to exposure in pregnancy to chemical products for domestic work and to hair dye. The risk associated with the latter was higher among 0–17 month old children (OR = 5.5, 95%CI: 1.0–29.3). Risk was increased for children whose mothers had suffered work related exposure in the preconception period to solvents (OR = 2.0 95%CI: 1.0–4.1) and in particular to aromatic hydrocarbons (OR = 9.2, 95%CI: 2.4–34.3). No association was observed with ELF-MF exposure. A higher risk was found among children with congenital malformations (OR = 4.9, 95%CI: 1.8–13.6) or neurofibromatosis (2 cases and 0 controls, p = 0.016).ConclusionsOur study suggests maternal exposure to hair dyes and aromatic hydrocarbons plays a role and deserves further investigation. The association with congenital malformations might also be explained by over-diagnosis.External exposure, in particular during and before pregnancy might contribute to NB occurrence.     

Patient doses and occupational exposure in a hybrid operating room

PurposeThis study aimed to characterize the radiation exposure to patients and workers in a new vascular hybrid operating room during X-ray-guided procedures.MethodsDuring one year, data from 260 interventions performed in a hybrid operating room equipped with a Siemens Artis Zeego angiography system were monitored. The patient doses were analysed using the following parameters: radiation time, kerma-area product, patient entrance reference point dose and peak skin dose. Staff radiation exposure and ambient dose equivalent were also measured using direct reading dosimeters and thermoluminescent dosimeters.ResultsThe radiation time, kerma-area product, patient entrance reference point dose and peak skin dose were, on average, 19:15 min, 67 Gy·cm², 0.41 Gy and 0.23 Gy, respectively. Although the contribution of the acquisition mode was smaller than 5% in terms of the radiation time, this mode accounted for more than 60% of the effective dose per patient. All of the worker dose measurements remained below the limits established by law.ConclusionsThe working conditions in the hybrid operating room HOR are safe in terms of patient and staff radiation protection. Nevertheless, doses are highly dependent on the workload; thus, further research is necessary to evaluate any possible radiological deviation of the daily working conditions in the HOR.