Cylindrical ionization chamber response in static and dynamic 6 and 15 MV photon beams

Purpose.To investigate the response of the CC13 ionization chamber under non-reference photon beam conditions, focusing on penumbra and build-up regions of static fields and on dynamic intensity-modulated beams.Methods. Measurements were performed in 6 MV 100 × 100, 20 × 100, and 20 × 20 mm²static fields. Monte Carlo calculations were performed for the static fields and for 6 and 15 MV dynamic beam sequences using a Varian multi-leaf collimator. The chamber was modelled using EGSnrc egs_chamber software. Conversion factors were calculated by relating the absorbed dose to air in the chamber air cavity to the absorbed dose to water. Correction and point-dose correction factors were calculated to quantify the conversion factor variations.Results. The correction factors for positions on the beam central axis and at the penumbra centre were 0.98-1.02 for all static fields and depths investigated. The largest corrections were obtained for chamber positions beyond penumbra centre in the off-axis direction. Point-dose correction factors were 0.54-0.71 at 100 mm depth and their magnitude increased with decreasing field size and measurement depth. Factors of 0.99-1.03 were obtained inside and near the integrated penumbra of the dynamic field at 100 mm depth, and of 0.92-0.94 beyond the integrated penumbra centre. The variations in the ionization chamber response across the integrated dynamic penumbra qualitatively followed the behaviour across penumbra of static fields.Conclusions. Without corrections, the CC13 chamber was of limited usefulness for profile measurements in 20-mm-wide fields. However, measurements in dynamic small irregular beam openings resembling the conditions of pre-treatment patient quality assurance were feasible. Uncorrected ionization chamber response could be applied for dose verification at 100 mm depth inside and close to large gradients of dynamically accumulating high- and low-dose regions assuming 3% tolerance between measured and calculated doses.

Effects of COVID-19 on the Human Central Olfactory System: A Natural Pre-Post Experiment

BACKGROUND AND PURPOSE

Reduced olfactory function is the symptom with the highest prevalence in coronavirus disease 2019 (COVID-19) with nearly 70% of infected individuals experiencing partial or total loss of their sense of smell at some point during the disease. The exact cause is not known, but beyond peripheral damage, studies have demonstrated insults to both the olfactory bulb and central olfactory brain areas. However, these studies often lack both baseline pre-COVID-19 assessments and control groups, and the effects could, therefore, simply reflect pre-existing risk factors.

MATERIALS AND METHODS

Shortly before the COVID-19 outbreak, we completed an olfactory-focused study, which included structural MR brain images and a full clinical olfactory test. Opportunistically, we invited participants back 1 year later, including 9 participants who had experienced mild-to-moderate COVID-19 (C19+) and 12 who had not (C19-), creating a natural pre-post experiment with a control group.

RESULTS

Despite C19+ participants reporting subjective olfactory dysfunction, few showed signs of objectively altered function. Critically, all except 1 individual in the C19+ group had reduced olfactory bulb volume (average reduction, 14.3%), but this did not amount to a significant statistical difference compared with the control group (2.3%) using inference statistics. We found no morphologic differences in olfactory brain areas but stronger functional connectivity between olfactory brain areas in the C19+ group at the postmeasure.

CONCLUSIONS

Our data suggest that COVID-19 might cause long-term reduction in olfactory bulb volume and altered functional connectivity but with no discernible morphologic differences in cerebral olfactory regions.

Antimicrobial-resistant Salmonella is detected more frequently in feed milling equipment than in raw feed components or processed animal feed

Food for human and animal consumption can provide a vehicle for the transfer of pathogenic and antimicrobial‐resistant bacteria into the food chain. We investigated the antimicrobial susceptibility of 453 Salmonella isolates collected from raw feed components, equipment and finished feed from 17 commercial feed mills in Australia between 2012 and 2021. Previous studies have found Salmonella prevalence and the diversity of Salmonella serotypes are greatest in the raw feed components. We, therefore, hypothesised that we would find a greater proportion of antimicrobial‐resistant Salmonella isolates in the raw feed components compared to other sample types. We found that of 453 isolates tested, 356 (0.80) were susceptible to all antimicrobials tested, 49 (0.11) were nonsusceptible to streptomycin only and 48 (0.11) were resistant to two or more antimicrobials. Of the 48 antimicrobial‐resistant isolates, 44 were found in feed milling equipment, two in raw feed components and two in finished feed. Statistical analysis, using a logistic regression with random effects model, found that the population‐adjusted mean probability of detecting antimicrobial‐resistant Salmonella isolates from feed milling equipment of 0.39, was larger than the probability of detecting resistant isolates in raw feed components 0.01, (P < 0.001) and in finished feed, 0.11, (P = 0.006). This propensity for antimicrobial‐resistant bacteria to colonise feed milling equipment has not been previously reported. Further studies are required to understand the ecology of antimicrobial‐resistant Salmonella in the feed milling environment.

Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry

PURPOSE

To investigate the sensitivity of Monte Carlo (MC) calculated lung dose distributions to lung tissue characterization in external beam radiotherapy of breast cancer under Deep Inspiration Breath Hold (DIBH).

METHODS

EGSnrc based MC software was employed. Mean lung densities for one hundred patients were analysed. CT number frequency and clinical dose distributions were calculated for 15 patients with mean lung density below 0.14 g/cm³. Lung volume with a pre-defined CT numbers was also considered. Lung tissue was characterized by applying different CT calibrations in the low-density region and air-lung tissue thresholds. Dose impact was estimated by Dose Volume Histogram (DVH) parameters.

RESULTS

Mean lung densities below 0.14 g/cm³ were found in 10% of the patients. CT numbers below -960 HU dominated the CT frequency distributions with a high rate of CT numbers at -990 HU. Mass density conversion approach influenced the DVH shape. V_4Gy and V_8Gy varied by 7% and 5% for the selected patients and by 9% and 3.5% for the pre-defined lung volume. V_16Gy and V_20Gy, were within 2.5%. Regions above 20 Gy were affected. Variations in air- lung tissue differentiation resulted in DVH parameters within 1%. Threshold at -990 HU was confirmed by the CT number frequency distributions.

CONCLUSIONS

Lung dose distributions were more sensitive to variations in the CT calibration curve below lung (inhale) density than to air-lung tissue differentiation. Low dose regions were mostly affected. The dosimetry effects were found to be potentially important to 10% of the patients treated under DIBH.

Targeted delivery of antisense oligonucleotides to pancreatic β-cells

Antisense oligonucleotide (ASO) silencing of the expression of disease-associated genes is an attractive novel therapeutic approach, but treatments are limited by the ability to deliver ASOs to cells and tissues. Following systemic administration, ASOs preferentially accumulate in liver and kidney. Among the cell types refractory to ASO uptake is the pancreatic insulin-secreting β-cell. Here, we show that conjugation of ASOs to a ligand of the glucagon-like peptide-1 receptor (GLP1R) can productively deliver ASO cargo to pancreatic β-cells both in vitro and in vivo. Ligand-conjugated ASOs silenced target genes in pancreatic islets at doses that did not affect target gene expression in liver or other tissues, indicating enhanced tissue and cell type specificity. This finding has potential to broaden the use of ASO technology, opening up novel therapeutic opportunities, and presents an innovative approach for targeted delivery of ASOs to additional cell types.

VIRUS — A Laboratory Information System for Clinical Virology

A system covering request registration, analytical orders, printing of worksheets, result reporting, result control and printing of patient reports is presented. Additionally, interim reports can be produced; accounting is automatic, and group requests and requests for new analyses of old samples can be handled. The system meets the demand for retrospective analysis which arises when acute intermediate and convalescent sera have to be analyzed simultaneously. Consequently, results from the same type of analysis performed on the same sample on different occasions can be handled and presented in a clear way on the VDU and on the report.

All work is performed on-line in real time via VDU screens. All data are stored on a 3 x 100 Mbyte disk chive which can accommodate approximately 6 years’ work.

The system has been implemented as a terminal system with 5 VDU: s and one line printer connected to an IBM 370/158 computer. The IMS data base management system has been utilized.

Lactate improves SAPS 3 prognostication

INTRODUCTION

Lactate concentration is known to be a strong predictor of mortality, but is not included in any of the major intensive care scorings systems such as the Simplified Acute Physiology Score (SAPS 3). The objective of this study was to investigate the prognostic value of lactate concentration when combined with SAPS 3.

MATERIALS AND METHODS

In the period of 2008 to June 2017 the general intensive care unit at Skåne University Hospital in Lund, Sweden had 5141 first-time admissions. Of these, 3039 patients had lactate concentrations analysed within 1 h of admission.

RESULTS

As expected, lactate concentration was found to be strongly related to 30-day mortality. Lactate concentration was found to be a SAPS 3 independent predictor of mortality (odds ratio 1.08, 95% confidence interval 1.05-1.11, P < 0.001), but did not improve the area under the receiver operating characteristic curve (AUC) (AUC 78.9% vs. 78.7%, P = 0.053). However, we found that lactate added prognostic value to SAPS 3 for patients with cardiac arrest (AUC 79.6% vs. 76.4%, P = 0.0082) and sepsis (AUC 75.1% vs. 72.7%, P = 0.033).

CONCLUSION

Even compared to our current prognostication model, SAPS 3, lactate concentration was found to be an independent predictor for all diagnoses, cardiac arrest and sepsis. The addition of lactate concentration level improved the AUC for cardiac arrest and sepsis, but not for all diagnoses.

Boys have better short-term and long-term survival rates after intensive care admissions than girls

AIM

We investigated possible gender differences in paediatric intensive care morbidity-adjusted mortality.

METHODS

In this study, data on all 21 972 paediatric intensive care admissions in Sweden between 2008 and 2015 were analysed regarding morbidity-adjusted survival, using Cox regression, with age, gender and estimated mortality ratio as dependent variables and using the standardised mortality ratio at 90 days after admission. The data were obtained from the Swedish Intensive Care Registry.

RESULTS

We found that boys had better overall survival than girls (hazard ratio 0.91 for boys, p = 0.035). In addition, the 90-day survival was also better for boys (standardised mortality ratio 0.85 for boys versus 1.02 for girls, p = 0.0014). The survival advantage was most evident in children less than a year old and for nonsurgical patients. The male advantage was also seen in children admitted with respiratory insufficiency and seizures and was furthermore independent of any concurrent cardiac condition. We did not find any gender difference in the intensity of care or length of stay when corrected for morbidity.

CONCLUSION

This study showed that boys have better outcomes than girls after intensive care admissions. The difference does not seem to be based on inequality of care.

Dental status in nursing home residents with domiciliary dental care in Sweden

OBJECTIVE

To describe the dental health status of elderly people in nursing homes receiving domiciliary dental care.

DESIGN

Case note review.

CLINICAL SETTING

Nursing homes in 8 Swedish counties.

PARTICIPANTS

Care dependent elderly people (≥65 years).

METHODS

Clinical data, including the number of remaining natural teeth, missing and decayed teeth (manifest dental caries) and root remnants, recorded by dentists according to standard practices. Medical and dental risk assessments were performed.

RESULTS

Data were available for 20,664 patients. Most were women (69.1%), with a mean age of 87.1 years (SD 7.42, range 65-109). The mean age for men was 83.5 years (SD 8.12, range 65-105). Two or more medical conditions were present in most of the population. A total of 16,210 individuals had existing teeth of whom 10,974 (67.7%) had manifest caries. The mean number of teeth with caries was 5.0 (SD 5.93) corresponding to 22.8% of existing teeth. One in four individuals were considered to have a very high risk in at least one professional dental risk assessment category.

CONCLUSIONS

Care dependent elderly in nursing homes have very poor oral health. There is a need to focus on the oral health-related quality of life for this group of frail elderly during their final period of life.

Randomized clinical trial of Appendicitis Inflammatory Response score-based management of patients with suspected appendicitis

BACKGROUND

The role of imaging in the diagnosis of appendicitis is controversial. This prospective interventional study and nested randomized trial analysed the impact of implementing a risk stratification algorithm based on the Appendicitis Inflammatory Response (AIR) score, and compared routine imaging with selective imaging after clinical reassessment.

METHOD

Patients presenting with suspicion of appendicitis between September 2009 and January 2012 from age 10 years were included at 21 emergency surgical centres and from age 5 years at three university paediatric centres. Registration of clinical characteristics, treatments and outcomes started during the baseline period. The AIR score-based algorithm was implemented during the intervention period. Intermediate-risk patients were randomized to routine imaging or selective imaging after clinical reassessment.

RESULTS

The baseline period included 1152 patients, and the intervention period 2639, of whom 1068 intermediate-risk patients were randomized. In low-risk patients, use of the AIR score-based algorithm resulted in less imaging (19·2 versus 34·5 per cent; P < 0·001), fewer admissions (29·5 versus 42·8 per cent; P < 0·001), and fewer negative explorations (1·6 versus 3·2 per cent; P = 0·030) and operations for non-perforated appendicitis (6·8 versus 9·7 per cent; P = 0·034). Intermediate-risk patients randomized to the imaging and observation groups had the same proportion of negative appendicectomies (6·4 versus 6·7 per cent respectively; P = 0·884), number of admissions, number of perforations and length of hospital stay, but routine imaging was associated with an increased proportion of patients treated for appendicitis (53·4 versus 46·3 per cent; P = 0·020).

CONCLUSION

AIR score-based risk classification can safely reduce the use of diagnostic imaging and hospital admissions in patients with suspicion of appendicitis. Registration number: NCT00971438 ( http://www.clinicaltrials.gov).

Factors Affecting Older Persons' Ability to Manage Oral Hygiene: A Qualitative Study

A great challenge for the dental service is to support the growing group of elderly people with preserving good oral health throughout their lives. Limitations in the ability to manage oral hygiene and an increased number of risk factors are often reflected by poor oral health. Thus, the need for individualized support and oral health procedures based on the older person's condition is significant. Deficiencies in the motor skills needed to manage oral hygiene are well known, but other factors that affect the ability are not well studied. The aim of the present study was to identify factors that may affect an elderly person's ability to perform oral hygiene self-care, which is the first step to develop a more comprehensive "oral hygiene ability index." The design of the study was qualitative. Data were collected from 4 focus group interviews with a total of 23 participants. Three of the groups consisted of dental hygienists, occupational therapists, and assistant nurses, all working with elderly persons. The fourth group was made up of elderly people (72-89 years). Content analysis was used to analyze the data. The latent content was formulated into the core category, "oral hygiene-a complex activity." Three categories emerged: "psychological," "environmental," and "functional" dimensions. The psychological dimension described attitude/motivation, emotions, and cognitive factors. The environmental dimension included practical conditions and social context. The functional dimension dealt with bodily and oral function as well as the senses. In conclusion, self-care with respect to oral hygiene is a complex activity for elderly persons and includes a large number of factors. These factors should be taken into consideration when developing a future oral hygiene ability index. Knowledge Transfer Statement: Various factors may affect the ability to manage oral hygiene self-care. Impaired ability to manage oral hygiene, in combination with an increased number of risk factors, often results in deteriorating oral health and impaired quality of life in older persons. Factors necessary to manage oral hygiene were identified in a qualitative study of dental hygienists, occupational therapists, and assistant nurses, all working with elderly patients, and a group of elderly persons. The results of this study may be important for clinical oral health work with older patients and for the planning of oral health and social care interventions for the growing group of older people.

Linac4 H⁻ ion sources

CERN's 160 MeV H(-) linear accelerator (Linac4) is a key constituent of the injector chain upgrade of the Large Hadron Collider that is being installed and commissioned. A cesiated surface ion source prototype is being tested and has delivered a beam intensity of 45 mA within an emittance of 0.3 π ⋅ mm ⋅ mrad. The optimum ratio of the co-extracted electron- to ion-current is below 1 and the best production efficiency, defined as the ratio of the beam current to the 2 MHz RF-power transmitted to the plasma, reached 1.1 mA/kW. The H(-) source prototype and the first tests of the new ion source optics, electron-dump, and front end developed to minimize the beam emittance are presented. A temperature regulated magnetron H(-) source developed by the Brookhaven National Laboratory was built at CERN. The first tests of the magnetron operated at 0.8 Hz repetition rate are described.

Discovery of AZD8165 – a clinical candidate from a novel series of neutral thrombin inhibitors

A novel series of neutral thrombin inhibitors has been developed using a selection process based on docking experiments and property calculations and predictions.

The impact of oral health on daily performances and its association with clinical variables in a population in Zambia

OBJECTIVE

The aim of this study was to investigate oral impacts on daily performance and to relate these data to oral clinical variables.

MATERIAL AND METHODS

The study was performed at a dental clinic in Livingstone, Zambia, and included 78 subjects (mean age 28, range 15-48 years) consecutively recruited in connection with a dental care visit. Data were collected through a structured interview using the Oral Impacts on Daily Performances (OIDP) index measuring oral health-related quality of life followed by a clinical examination.

RESULTS

Oral health affected one or more daily performances during the last 6 months for 61.5% of the subjects. 'Difficulty of eating and enjoying food' was the performance reported most frequently (42.3%), and 'speaking and pronouncing clearly' was least often reported (10.3%). DMFT was 3.8, ±3.6 (mean ± SD; range 0-15). A majority of the individuals had periodontal pockets ≥4 mm (mean 4.3, ±2.6) (94.9%) and gingival bleeding on probing >20% (88.5%). Two or more decayed teeth were shown to be significantly associated (OR 4.6, CI 1.2-17.1) with one or more oral impacts on daily performances in a multivariate logistic regression analysis.

CONCLUSIONS

This study shown that there is a significant association between decayed teeth and oral impacts on daily performances. More research is needed, however, for deeper understanding of oral health problems and their impacts on daily life in Zambia.

Predicting exposure of wildlife in radionuclide contaminated wetland ecosystems

Many wetlands support high biodiversity and are protected sites, but some are contaminated with radionuclides from routine or accidental releases from nuclear facilities. This radiation exposure needs to be assessed to demonstrate radiological protection of the environment. Existing biota dose models cover generic terrestrial, freshwater, and marine ecosystems, not wetlands specifically. This paper, which was produced under IAEA's Environmental Modelling for Radiation Safety (EMRAS) II programme, describes an evaluation of how models can be applied to radionuclide contaminated wetlands. Participants used combinations of aquatic and terrestrial model parameters to assess exposure. Results show the importance of occupancy factor and food source (aquatic or terrestrial) included. The influence of soil saturation conditions on external dose rates is also apparent. In general, terrestrial parameters provided acceptable predictions for wetland organisms. However, occasionally predictions varied by three orders of magnitude between assessors. Possible further developments for biota dose models and research needs are identified.