Remainder Tissues Research Articles

PSIII-20 Transcriptional and Functional Analyses of Intramuscular, Subcutaneous, and Visceral Adipose Tissue in Finished Beef Cattle

Abstract Intramuscular adipose tissue (IMAT; marbling) deposition is a highly desired trait in beef cattle. Unlike excessive subcutaneous (SCAT) and visceral (VIAT) adipose tissue, which have relatively low value, increased marbling is associated with meat sensory traits and is a primary factor influencing beef quality grading in the U.S. However, this trait is difficult to achieve. Our objective was to assess depot-specific characteristics and gene profile of IMAT, SCAT, and VIAT in beef cattle. IMAT and SCAT samples from the longissimus muscle (9-11th ribs), and VIAT from the greater omentum were collected from four beef animals at harvest. Adipose tissue (AT) samples were flash frozen in liquid nitrogen, followed by RNA extraction (Trizol reagent) and RNA sequencing analysis on an Illumina Novaseq 6000 platform to generate 150 bp paired-end reads. DESeq2 R package was used for differential gene expression analysis (DEG) and DEG (P ≤ 0.05, log2FC ≥ 1) were evaluated for KEGG enrichment pathways. Remainder tissue samples were assessed for viscoelasticity (rheometer), collagen fibrillogenesis (kinetics), and adipocyte size (K2 Cellometer). Transcriptome analysis revealed over 4,000 DEG between IMAT and SCAT, over 3,000 DEG between VIAT and IMAT, and 1,018 DEG between VIAT and SCAT, thus indicating substantial transcriptional diversity among AT depots (Figure 1). Top upregulated genes in SCAT vs. IMAT were associated with increased lipid accumulation and regulation such as LIPE, LEP, ADIPOQ, PPARG, and extracellular matrix (ECM) remodeling, including collagens, MMP14, and TIMP4. Accordingly, enrichment analysis revealed an activation of PPARG signaling pathways and fatty acid metabolism in SCAT vs. IMAT, which are key for lipogenesis and adipogenesis (Figure 2). IMAT showed activation of pathways for thermogenesis and oxidative phosphorylation compared with both SCAT and VIAT, indicating that IMAT utilization may be more directed towards muscle function and development (Figure 2 and 3). Top VIAT DEG were primarily associated with immune cell adhesion, and immune response (CDHR1, TENM2, and TNFRSF9), suggesting a pro-inflammatory profile of visceral adiposity. Notably, enrichment analysis showed an activation of the immune function in VIAT compared with IMAT and SCAT (Figures 3 and 4). In agreement with transcriptome analysis, adipocyte size was increased in SCAT vs. IMAT and VIAT, implying higher lipid accumulation (Figure 5). SCAT was also stiffer and had increased collagen fibrillogenesis compared with IMAT, suggesting a key role for ECM in mechanisms of AT adipogenesis and lipogenesis (Figure 5). In summary, these results indicate that AT anatomical location impacts AT transcriptome, which may translate into functional differences in adipogenesis and ECM remodeling. Understanding transcriptional and functional differences among IMAT, SCAT and VIAT can help on the identification of target genes to modulate AT deposition in distinct areas of the body, therefore, improving quality of beef carcasses and industry profitability.

ПРИМЕНЕНИЕ НОВЫХ РЕКОМЕНДАЦИЙ МКРЗ ДЛЯ РАСЧЕТА ДОЗ ПЕРСОНАЛА ПРИ ИНГАЛЯЦИОННОМ ПОСТУПЛЕНИИ РАДИОНУКЛИДОВ УРАНА

Purpose: Harmonization and improvement of the system for regulating the internal radiation exposure of workers and the basic requirements for ensuring radiation safety, taking into account the application of new international requirements and recommendations. Material and methods: A brief description of the procedure for calculating absorbed and equivalent doses in organs and tissues after the intake of radionuclides into the human body is presented, using the biokinetic and dosimetric models adopted in the new ICRP recommendations, as well as a discussion of the impact of these changes on the results of calculating dose coefficients for the case of inhalation intake of uranium-235 radionuclide. Results: The effective dose values and equivalent doses to organs and tissues for workers were calculated depending on the time after a single inhalation intake of uranium-235 aerosol, according to new models [1–12] and according to previous ICRP models [15, 16]. The calculation of the effective dose according to the new models included calculations of equivalent doses for 14 main organs and tissues and 13 organs and tissues classified as “remainder tissues” as described in ICRP Publication 103 [3]. The committed effective dose was then calculated according to the new approach using the average of the equivalent doses for the reference adult male, HTM, and the reference adult female, HTF, as well as the tissue and organ weighting factors, WT, adopted in ICRP Publication 103. The values of the effective dose and equivalent doses on the red bone marrow, lungs and remainder tissues vs time in the range from several days to 18250 days (50 years) after a single inhalation intake of an aerosol of uranium-235 for standard value AMAD=5 µm and types of compounds F, M, S, F/M and M/S are presented according to new and previous ICRP models. It is shown that the value of the dose coefficient for type F, calculated by new models, is 2.6 times (2.3E-07÷6.0E-07) less than that calculated by previous ICRP models, and the value of the dose coefficient for type F/M calculated by new models is 1.6 times (3.8E-07÷6.0E-07) less than the value of the dose coefficient for type F calculated by previous ICRP models. For uranium trioxide UO3, taking into account its transition from compound type M to F/M, the value of the dose coefficient for committed effective dose according to the updated model of the respiratory tract is 4.7 times (3.8E-07÷1.8E-06) less than the corresponding value for the previous model of the type M respiratory tract. The committed effective dose value for compound type M, calculated using the new models, is 1.4 times (1.3E-06÷1.8E-06) less than the same value calculated using the previous ICRP models. The value of the committed effective dose for type M/S compounds (which, according to the new model of the respiratory tract, include uranium oxide U3O8 and dioxide UO2), calculated according to new models, is 1.2 times (5.1E-06÷6.1E-06) less than the value calculated from previous ICRP models for type S compounds (which included U3O8 and UO2 in the previous respiratory tract model). Conclusion: From the above data it follows that in case of the adoption of national radiation safety standards to new ICRP models, differences in the values of dose coefficients will result in a change of annual limits of intake (ALI) in the corresponding proportion for the types of uranium aerosol compounds noted above.

Effective dose for kidney-ureter-bladder plain radiography, intravenous urography, and abdominal computed tomography scan: A phantom study

Abdominal colic pain or hematuria is suspected to be caused by urinary tract stones. Commonly used X-ray examinations include kidney-ureter-bladder plain radiography (KUB), intravenous urography (IVU), and abdominal computed tomography (CT). In this study, a high-sensitivity thermoluminescent dosimeter (TLD) was embedded in a Rando phantom to directly measure organ dose and evaluate effective dose. During each experiment, 139 TLD measurement points that cover almost all organs (as recommended by the ICRP 103 report) were examined. Red bone-marrow and remainder tissues have a high tissue weighting factor (0.12), and they are widely distributed. In the phantom, 34 TLDs and 31 TLDs were embedded in the red bone-marrow and remainder tissues to improve the accuracy and representativeness of organ doses. The detailed organ dose distributions for KUB, IVU, and abdominal CT are presented. The effective doses for KUB and IVU were 0.22 and 1.51 mSv, respectively, and those for two abdominal CTs were 8.21 and 9.27 mSv. This experiment presents a conversion factor of 0.0177 mSv·mGy−1 cm−1 for the abdominal CT examination, which differs from most of the conversion factors obtained through the Monte Carlo simulation method.

Pharmacokinetics and residue elimination of norfloxacin in rainbow trout (Oncorhynchus mykiss).

We studied the metabolism and elimination of norfloxacin in rainbow trout (Oncorhynchus mykiss) following a single oral administration of 50mg/kg at 15±2°C. Norfloxacin was measured by high-performance liquid chromatography-tandem mass spectrometry in plasma, muscle, liver, kidney, skin and remainder tissues, and the concentrationtime curve was characterized by a double peak. The drug was absorbed rapidly; the first peak appeared within 4h, and the second peak appeared within 24h in all substrates tested. The maximal concentrations in plasma, muscle, liver and kidney were 0.468mg/L, 14.146mg/kg, 6.445mg/kg and 0.977mg/kg, respectively. The distribution half-life was 5.814, 9.026, 17.027 and 1.004h, respectively. The elimination half-life was 41.205, 41.667, 44.896 and 54.908h, respectively. Using the kidney as the reference tissue for norfloxacin monitoring in aquaculture and 2μg/kg as a maximum residue limit standard, it takes 555 temperature-day (°C days) for norfloxacin to be completely eliminated from rainbow trout.

Monte Carlo calculation of the organ equivalent dose and effective dose due to immersion in a 16N beta source in air using the ICRP reference phantoms

This work summarises the results of a comparison organized by EURADOS focused on the usage of the ICRP Reference Computational Phantoms. This activity aimed to provide training for the implementation of voxel phantoms in Monte Carlo radiation transport codes and the calculation of the dose equivalent in organs and the effective dose. This particular case describes a scenario of immersion in a16N beta source distributed in the air of a room with concrete walls where the phantom is located. Seven participants took part in the comparison of results using GEANT4, TRIPOLI-4 and MCNP family codes, and there was detected a general problem when calculating the dose to skeletal tissue and the remainder tissue. After a process of feedback with the participants the errors were corrected and the final results reached an agreement of ±5%.

DOSE CONVERSION COEFFICIENTS FROM MONOENERGETIC NEUTRONS COMPUTED WITH THE MCNP6.2 CODE IN THE VIP-MAN PHANTOM.

Computational estimates of dosimetric quantities from external exposures to neutron fields are valuable to ongoing radiation protection studies that are of interest to US defense-focused organizations. Conversion coefficients for fluence-to-absorbed dose and fluence-to-effective dose were computed using version 6.2 of the Monte Carlo N-Particle® code (MCNP6.2) in the visible photographic man (VIP-Man) numerical model for 45 monoenergetic neutron fields between 10-9 and 20MeV under six irradiation geometries. Comparisons to the formative VIP-Man study by Bozkurt etal. revealed excellent agreement. The mean relative difference between our VIP-Man/MCNP6.2-computed and the International Commission on Radiological Protection (ICRP) 116-published absorbed dose conversion coefficients in 14 organs and remainder tissues under all geometries was 4.7%, which is within ICRP-reported variations. The effective dose coefficients computed with VIP-Man/MCNP6.2 were strongly similar to ICRP 116 values in all geometries except for posterior-anterior, where the difference was attributed to shielding of anterior organs by the relatively fatty composition of the VIP-Man phantom.

Effective doses of dental cone beam computed tomography: effect of 360-degree versus 180-degree rotation angles

The aims of this study were to compare radiation absorbed dose (AD) and effective dose (ED) to tissues from cone beam computed tomography (CBCT) scans with 360-degree versus 180-degree rotations with use of different fields of view (FOV), to compare EDs calculated from measured ADs versus dose area product (DAP) values, and to compare doses to the lens of the eye (LOE) from different scan parameters. ADs for each protocol were measured in tissues, including the LOE, by using an anthropometric phantom. EDs were calculated on the basis of dosimetry (EDm) and DAP values (EDd). Dose differences were determined with analysis of variance (ANOVA). ADs and EDs were substantially lower for 180-degree rotation scans compared with 360-degree rotation scans (P < .01). Remainder tissues had the greatest effect on effective dose for most FOVs. Doses were generally lower with small FOVs compared with large FOVs. Most EDm values were lower than EDd values in large FOVs but higher in small FOVs. Differences in EDm and EDd were variable and unpredictable. LOE doses were smaller with the 180-degree scans and smaller FOVs. Radiation doses were generally lower with 180-degree rotation scans and smaller FOVs. These parameters should be used for CBCT acquisitions, whenever possible, and should be made available in all units.

Dose estimate for cone beam CT equipment protocols using Monte Carlo simulation in computational adult anthropomorphic phantoms

Cone beam computed tomography (CBCT) has become essential for dental diagnoses in the last decade. This is supported by its low cost and low doses, when compared to medical CT. Following this increase in CBCT procedures, it is necessary to ensure the image quality within low radiation doses to the patients. This is an especially difficult challenge in CBCT, given the number of equipment models (more than 50), radiographic techniques that may be employed, and technical information not available to the users by the manufacturers. The objective of this study was to estimate the cancer risk, effective and absorbed doses in tissues and organs for CBCT protocols intended for dental use. Monte Carlo (MC) simulations were used to estimate these quantities in tissues and organs with radiological importance, as those suggested by the International Commission of Radiological Protection (ICPR) report ICRP 103. Five different fields of view (FOV) were simulated to i-Cat Classic CBCT, using the MCNPX code. The virtual anthropomorphic phantoms FASH3 (Female Adult MeSH) and MASH3 (Male Adult MeSH) were also used. The effective dose estimative was in the range 75.15–142.20 μSv. The largest contribution to the effective dose was from the salivary glands (17%), thyroid (27%) and remainder tissues (28%). The results of this work showed that the effective and absorbed doses in tissues/organs vary according to the FOV, exposure parameters, and the positioning of the beam, relative to the radiosensitive organs. Furthermore, for the same exposure conditions, women can exceed the total risk of cancer by 26–34%, when compared to men.

Imaging Optimization of Temporal Bones With Cochlear Implant Using a High-resolution Cone Beam CT and the Corresponding Effective Dose.

To evaluate the impact of tube voltage, tube current, pulse number, and magnification factor on the image quality of a novel experimental set-up and the corresponding radiation. Six human temporal bones with cochlear implant were imaged using various tube voltages, tube currents, pulse numbers, and magnification. The effect of radiation was evaluated using a metaloxide semiconductor field-effect transistor (MOSFET) dosimeter device on an anthropomorphic RANDO RAN102 male head phantom. A copper and aluminum combination filter was used for hardware filtration. Overall, 900 frames, 11 mA, and 88 kV provided the best image quality. In temporal bones imaged with the optimized parameters, the cochlea, osseous spiral lamina, modiolus, stapes, round window niche, and oval window landmarks were demonstrated with anatomic structures still fully assessable in all parts and acceptable image quality. The most dominant contributor to the effective dose was bone marrow (36%-37 %) followed by brain (34%-36%), remainder tissues (12%), extra-thoracic airways (7%), and oral mucosa (5%). By increasing the number of frames, the image quality of the inner ear details obtained using the novel cone-beam computed tomography improved.

AP versus PA positioning in lumbar spine computed radiography: Image quality and individual organ doses

PurposeRadiological imaging examinations must be optimised in order to ensure that the radiation dose is kept as low as reasonably possible (ALARP). The aim of this study was to compare anteroposterior (AP) and posteroanterior (PA) projections of the lumbar spine, at various kVp increments, in order to establish optimum parameters. MethodsAn anthropomorphic phantom was imaged in both the AP/PA projections and at various kVp increments. Acquisitions were undertaken using a Wolverson Acroma X-ray unit and processed using an Agfa computed radiography (CR) unit. The entrance surface dose was recorded and converted to effective and organ doses using PCXMC 2.0 software. Five observers were then asked to evaluate the images, using a two-alternative force choice (2AFC) approach and a scale based on EC guidelines. ResultsThe PA projection lowered the mean effective dose by 19.8% and also the mean absorbed dose to the stomach (70.4%), colon (61.1%), remainder tissues (33.2%), ovaries (7.3%) and testes (15.9%). However, this was at the expense of slightly inferior image quality, not statistically significant. For AP projections, a higher kVp is a further option for dose reduction. ConclusionDose optimisation requires the production of an image that is acceptable for the purpose intended. Based on ALARP, and when taking into consideration the dose reductions in this study, it may now be time to routinely use PA projections when imaging the lumbar spine. The use of a higher kVp should also be considered as an option but would be more useful for AP projections.

Nutrients and non-volatile taste compounds in Chinese mitten crab by-products

Edible viscera (EV) and remainder tissues (RTs) are two by-products of Chinese mitten crab. The objective of this study was to assess the nutrient and non-volatile taste compound contents of EV and RTs. EV and RTs were high in fat (25.35 %) and protein (16.46 %), respectively. Both by-products were good sources of Zn, Fe, and Cu. Both samples contained unsaturated fatty acids (75 % of the total fatty acids) and a balanced ratio of essential fatty acids. The total amino acid content relative to protein in EV and RTs were 77.62 and 66.74 g/100 g, respectively. Alanine (sweet), glutamate (umami), and arginine (bitter/sweet) were the predominant free amino acids that contributed to pleasant flavors due to their taste activity values (TAVs) >1. TAVs of disodium 5′-adenosine monophosphate, disodium 5′-guanosine monophosphate, and disodium 5′-inosine monophosphate were >1 in RT but <1 in EV. Equivalent umami concentrations were 2.71 and 9.00 g MSG/100 g in EV and RTs, respectively, indicating that umami taste in both by-products was very intense. EV and RTs have high nutritional and flavor qualities and could be utilized as flavors and functional food ingredients.

Radiation exposure of patients undergoing whole-body FDG-PET/CT examinations: an update pursuant to the new ICRP recommendations.

Reinvestigation of the radiation exposure of patients undergoing whole-body [18F]FDG-PET/CT examinations pursuant to the revised recommendations of the ICRP. Conversion coefficients for equivalent organ doses were determined for realistic anthropomorphic phantoms of reference persons. Based on these data, conversion coefficients for the effective dose were calculated using the revised tissue-weighting factors that account for the different radiation susceptibilities of organs and tissues, and the redefinition of the group 'remainder tissues'. Despite the markedly changed values of the equivalent organ doses estimated for FDG and of the tissue-weighting factors, the conversion coefficient for the effective dose resulting from FDG administration decreases only slightly by 10 %. For whole-body CT scans it remains even unchanged. The updated dose coefficients provide a valuable tool to easily assess the generic radiation risk of patients undergoing whole-body PET/CT (or PET/MRI) examinations and can be used, amongst others, for protocol optimization.

SU‐E‐T‐276: Equivalent Dose in Children Receiving Craniospinal Irradiation with Photons in a Developing Country Or with Protons in a Developed Country

Purpose: Childhood cancer survivors who were treated with craniospinal irradiation (CSI) have a high risk of radiogenic late effects, for example second malignant neoplasms (SMNs). These effects can occur inside or outside of the therapeutic fields. Proton therapy, which is unavailable in developing countries, may offer the possibility to reduce the radiation dose in normal tissues and thereby reducing the risk of late effects. We quantified the equivalent dose in organs at risk for SMNs for 9 children ages 2 to 14 years who received proton CSI in a developed country and the doses they would have received from photon CSI in a developing country. Methods: For each child, 23.4‐Gy treatment plans were created according the standards of care of leading cancer centers in a developed country (proton CSI) and in a developing country (photon CSI). For each patient and clinic, equivalent dose was determined throughout the patients' bodies. In‐field dose was calculated using treatment planning systems of our clinics. Out‐of‐field dose was calculated using Monte Carlo simulations for proton CSI and applying a measurement‐based model for photon CSI. Mean equivalent dose was determined in organs at risk of SMNs‐‐red bone marrow, bladder, breasts, liver, lungs, ovaries, prostate, stomach, uterus, colon, skin, and remainder tissues. Results: Mean organ equivalent doses averaged over 9 all patients were less in proton CSI than in photon CSI in all organs and tissues except skin. We observed minor (&lt;30%) reductions in equivalent dose in the lungs, red bone marrow, and remainder tissues and larger (&gt;85%) reductions in all other organs. Conclusion: Equivalent dose was reduced for children receiving CSI with proton beams rather than photon beams. It may be possible to reduce the risk of radiogenic SMNs for children in developing countries needing CSI if proton therapy is made available to them. Fogarty International Center, National Institutes of Health, K01‐TW008409; National Cancer Institute, National Institutes of Health, R01‐CA131463‐01A1; Northern Illinois University through a subcontract of Department of Defense W81XWH‐08‐1‐0205; We do not have any conflicts of interest

Doses from radon progeny as a source of external beta and gamma radiation

Great deal of work has been devoted to determine doses from alpha particles emitted by (222)Rn and its progeny. In contrast, contribution of beta particles and following gamma radiation to total dose has mostly been neglected so far. The present work describes a study of the detriment of (222)Rn progeny for humans due to external exposure. Doses and dose conversion factors (DCFs) were determined for beta and gamma radiation in main organs and remainder tissue of the Oak Ridge National Laboratory phantom, taking into account (222)Rn progeny (214)Pb and (214)Bi distributed in the middle of a standard or typical room with dimensions 4 m × 5 m × 2.8 m. The DCF was found to be 7.37 μSv/WLM. Skin and muscle tissue from remainder tissue receives largest dose. Beta and gamma radiation doses from external exposure were compared with alpha, beta, and gamma doses from internal exposure where the source of radioactivity was the lungs. Total doses received in all main organs and remainder tissues were obtained by summing up the doses from external and internal exposure and the corresponding DCF was found to be 20.67 μSv/WLM.

Isolation and Characterization of Oviduct-specific Glycoproteins from Ampulla and Isthmus Parts of Cyclic and Acyclic Buffalo for Studying Differential Microenvironment

The present study characterized the glycoproteins synthesized by buffalo oviduct. Scanning electron microscopy analyses of the ampullary and isthmic segments of cyclic and acyclic buffaloes showed ultrastructural variations in ciliated and nonciliated cells. Mucosal proteins were extracted by scrapping of different segments of oviduct and, after centrifugation, the remainder tissues were subjected to establish primary cell culture system of oviduct epithelial cells and conditioned media were prepared. Time- and concentration-dependent effects of trypsinization on the establishment of primary monolayer culture showed that 0.25% trypsin for 1-2min at 37°C were the optimal conditions. Total protein content in oviductal tissues and conditioned media was quantified and analyzed by SDS-PAGE which showed marked variation in different segments of the oviduct. Western blot analysis revealed five major oviduct-specific glycoproteins (OGPs) in cyclic oviduct (ampulla and isthmus) with Mw 180, 95, 75, 66 and 35kDa in the oviduct extract and two glycoproteins with Mw 95 and 66kDa in conditioned media. However, in acyclic oviduct (ampulla and isthmus), three glycoproteins were immunostained with Mw 180, 95 and 66kDa in the oviduct extract and one glycoprotein with Mw 66kDa in conditioned media. Indirect Enzyme-Linked Immuno Sorbent Assay (ELISA) results showed significant differences of OGPs in different segments of cyclic and acyclic buffaloes and, thus, indicative of segmental variation in the synthesis and secretion of glycoproteins. Oviductal extract secretes more amounts of OGPs as compared to the conditioned medium. The role of these OGPs may be defined and exploited for influencing the fertilization process and/or subsequent embryonic development.

Estimation of paediatric organ and effective doses from dental cone beam CT using anthropomorphic phantoms.

Cone beam CT (CBCT) is an emerging X-ray technology applied in dentomaxillofacial imaging. Previous published studies have estimated the effective dose and radiation risks using adult anthropomorphic phantoms for a wide range of CBCT units and imaging protocols. Measurements were made five dental CBCT units for a range of imaging protocols, using 10-year-old and adolescent phantoms and thermoluminescent dosimeters. The purpose of the study was to estimate paediatric organ and effective doses from dental CBCT. The average effective doses to the 10-year-old and adolescent phantoms were 116 μSv and 79 μSv, respectively, which are similar to adult doses. The salivary glands received the highest organ dose and there was a fourfold increase in the thyroid dose of the 10-year-old relative to that of the adolescent because of its smaller size. The remainder tissues and salivary and thyroid glands contributed most significantly to the effective dose for a 10-year-old, whereas for an adolescent the remainder tissues and the salivary glands contributed the most significantly. It was found that the percentage attributable lifetime mortality risks were 0.002% and 0.001% for a 10-year-old and an adolescent patient, respectively, which are considerably higher than the risk to an adult having received the same doses. It is therefore imperative that dental CBCT examinations on children should be fully justified over conventional X-ray imaging and that dose optimisation by field of view collimation is particularly important in young children.

Construction of an extended library of adult male 3D models: rationale and results

In order to best cover the possible extent of heights and weights of male adults the construction of 25 whole body 3D models has been undertaken. Such a library is thought to be useful to specify the uncertainties and relevance of dosimetry calculations carried out with models representing individuals of average body heights and weights. Representative 3D models of Caucasian body types are selected in a commercial database according to their height and weight, and 3D models of the skeleton and internal organs are designed using another commercial dataset. A review of the literature enabled one to fix volume or mass target values for the skeleton, soft organs, skin and fat content of the selected individuals. The composition of the remainder tissue is fixed so that the weight of the voxel models equals the weight of the selected individuals. After mesh and NURBS modelling, volume adjustment of the selected body shapes and additional voxel-based work, 25 voxel models with 109 identified organs or tissue are obtained. Radiation transport calculations are carried out with some of the developed models to illustrate potential uses. The following points are discussed throughout this paper:- justification of the fixed or obtained models’ features regarding available and relevant literature data;- workflow and strategy for major modelling steps;- advantages and drawbacks of the obtained library as compared with other works.The construction hypotheses are explained and justified in detail since future calculation results obtained with this library will depend on them.

The role of Azadinium spinosum (Dinophyceae) in the production of azaspiracid shellfish poisoning in mussels

Azaspiracids (AZAs) are a group of lipophilic polyether compounds first detected in Ireland which have been implicated in shellfish poisoning incidents around Europe. These toxins regularly effect shellfish mariculture operations including protracted closures of shellfish harvesting areas for human consumption. The armoured dinoflagellate Azadinium spinosum Elbrächter et Tillmann gen. et sp. nov. (Dinophyceae) has been described as the de novo azaspiracid toxin producer; nonetheless the link between this organism and AZA toxin accumulation in shellfish has not yet been established. In August 2009, shellfish samples of blue mussel ( Mytilus edulis) from the Southwest of Ireland were analysed using liquid chromatography–tandem-mass spectrometry (LC–MS/MS) and were found to be above the regulatory limit (0.16 μg g −1 AZA-equiv.) for AZAs. Water samples from this area were collected and one algal isolate was identified as A. spinosum and was shown to produce azaspiracid toxins. This is the first strain of A. spinosum isolated from Irish waters. The Irish A. spinosum is identical with the other two available A. spinosum strains from Scotland (3D9) and from Denmark (UTHE2) in its sequence of the D1–D2 regions of the LSU rDNA. A 24 h feeding trial of blue mussels ( M. edulis) using an algal suspension of the Irish A. spinosum culture at different cell densities demonstrated that A. spinosum is filtered, consumed and digested directly by mussels. Also, LC–MS/MS analysis had shown that AZAs were accumulating in the shellfish hepatopancreas. The toxins AZA1 and -2 were detected in the shellfish together with the AZA analogues AZA3, AZA6, AZA17 and -19 suggesting that AZA1 and -2 are metabolised in the shellfish within the first 24 h after ingestion of the algae. The levels of AZA17 detected in the shellfish hepatopancreas (HP) were equivalent to the levels of AZA1 but in the remainder tissues the levels of AZA17 were four to five times higher than that of AZA1, only small quantities of AZA3 and -19 were present with negligible amounts of AZA6 detected after the 24 h period. This could have implications in the future monitoring of these toxins given that at present according to EU legislation only AZA1–AZA3 is regulated for. This is the first report of blue mussels’ ( M. edulis) feeding on the azaspiracid producing algae A. spinosum from Irish waters.

Effective dose range for dental cone beam computed tomography scanners

To estimate the absorbed organ dose and effective dose for a wide range of cone beam computed tomography scanners, using different exposure protocols and geometries. Two Alderson Radiation Therapy anthropomorphic phantoms were loaded with LiF detectors (TLD-100 and TLD-100 H) which were evenly distributed throughout the head and neck, covering all radiosensitive organs. Measurements were performed on 14 CBCT devices: 3D Accuitomo 170, Galileos Comfort, i-CAT Next Generation, Iluma Elite, Kodak 9000 3D, Kodak 9500, NewTom VG, NewTom VGi, Pax-Uni3D, Picasso Trio, ProMax 3D, Scanora 3D, SkyView, Veraviewepocs 3D. Effective dose was calculated using the ICRP 103 (2007) tissue weighting factors. Effective dose ranged between 19 and 368 μSv. The largest contributions to the effective dose were from the remainder tissues (37%), salivary glands (24%), and thyroid gland (21%). For all organs, there was a wide range of measured values apparent, due to differences in exposure factors, diameter and height of the primary beam, and positioning of the beam relative to the radiosensitive organs. The effective dose for different CBCT devices showed a 20-fold range. The results show that a distinction is needed between small-, medium-, and large-field CBCT scanners and protocols, as they are applied to different indication groups, the dose received being strongly related to field size. Furthermore, the dose should always be considered relative to technical and diagnostic image quality, seeing that image quality requirements also differ for patient groups. The results from the current study indicate that the optimisation of dose should be performed by an appropriate selection of exposure parameters and field size, depending on the diagnostic requirements.

An Algorithm for Lymphatic Node Placement in Hybrid Computational Phantoms—Applications to Radionuclide Therapy Dosimetry

The presence of lymphatic nodes within computational human phantoms is critical to the evaluation of tissue doses in lymphoma patients treated with targeted radionuclide therapy. Furthermore, the International Commission on Radiological Protection (ICRP) now considers the lymphatic nodes to be a radiosensitive tissue of the remainder tissues of the effective dose as defined in ICRP Publication 103. Lymphatic nodes have previously not been included within the structure of stylized phantoms and are only present within a few voxel-based phantoms through manual retagging of voxels of the residual soft tissues. In this paper, an automated methodology is introduced whereby lymphatic nodes are placed-in an anatomically realistic fashion-within the University of Florida adult male reference hybrid phantom. First, a total of 16 lymphatic node anatomical sites are defined within the phantom. These include the extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right), and popliteal (left and right) nodal regions. Secondly, individual lymphatic node positions are randomly sampled within spherical tissue regions centered at each previously selected lymphatic node site. Thirdly, smaller voxelized tissue spheres representing individual lymphatic nodes are then created to populate each nodal region of the phantom using a nominal nodal diameter. This process is repeated until a total lymphatic node mass is achieved to match age-dependent total reference masses derived from ICRP Publication 66 and 89 data. An illustrative set of radionuclide S-values for 131I are presented whereby regional lymphatic nodes are considered to be independent source and target regions of a reference lymphoma patient. As nodal size can easily be changed within individual nodal regions, the lymphatic node model suggested in this paper can be used to obtain realistic dosimetry for lymphoma patients treated with radionuclide therapy.