bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D tomodosimetry using long scintillating fibers: A feasibility study
Authors: Goulet Mathieu , Archambault Louis , Beaulieu Luc , Gingras Luc 
Published: September 2013

Purpose: 3D dosimetry is recognized as an ideal for patient‐specific quality assurance (QA) of highly conformal radiotherapy treatments. However, existing 3D dosimeters are not straightforward to implement in the clinic, as their read‐out procedure is often tedious and their accuracy, precision, and/or sample size exhibit limitations. The purpose of this work is to develop a 3D dosimeter based on the concept of tomodosimetry inside concentric cylindrical planes using long scintillating fibers for the QA of modern radiotherapy techniques such as intensity‐modulated radiation therapy (IMRT) or intensity‐modulated arc therapy (IMAT).Methods: Using a model‐based simulation, scintillating fibers were modeled on three concentric cylindrical planes of radii 2.5, 5.0, and 7.5 cm, inside a 10 cm radius water‐equivalent cylinder phantom. The phantom was set to rotate around its central axis, made parallel to the linac gantry axis of rotation. Light acquisitions were simulated using the calculated dose from the treatment planning software and reconstructed in each cylindrical plane at a resolution of 1 mm2 using a total‐variation minimization iterative reconstruction algorithm. The 3D dose was then interpolated from the reconstructed cylindrical plane doses at a resolution of 1 mm3. Different scintillating fiber patterns were compared by varying the angle of each fiber in its cylindrical plane and introducing a light‐tight cut in each fiber. The precision of the reconstructed cylindrical dose distribution was evaluated using a Poisson modeling of the acquired light signals and the accuracy of the interpolated 3D dose was evaluated using an IMRT clinical plan for a prostate case.Results: Straight scintillating fiber patterns with light‐tight cuts were the most accurate in cylindrical dose reconstruction, showing less than 0.5 mm distance‐to‐agreement in dose gradients and a mean local dose difference of less than 0.2% in the high dose region for a 10 × 10 cm2 field. The precision attained with this fiber configuration was less than 0.9% in the high dose, low gradient region of an IMRT segment for light acquisitions of 0.1 MU over a 360 degree rotation of the cylinder phantom. 3D dose interpolation for the IMRT clinical plan yielded an overall dose difference with the reference input of less than 1%, except in high dose gradients.Conclusions: Using long scintillating fibers inside rotating, concentric cylindrical planes, the authors demonstrate that their tomodosimetry method has the potential for high resolution, precise, and accurate 3D dosimetry. Moreover, because of its water‐equivalence and rotational symmetry, this design should find interesting application for both treatment QA and machine commissioning.
Template‐based CTA to x‐ray angio rigid registration of coronary arteries in frequency domain with automatic x‐ray segmentation
Authors: Aksoy Timur , Unal Gozde , Demirci Stefanie , Navab Nassir , Degertekin Muzaffer 
Published: September 2013

Purpose:A key challenge for image guided coronary interventions is accurate and absolutely robust image registration bringing together preinterventional information extracted from a three‐dimensional (3D) patient scan and live interventional image information. In this paper, the authors present a novel scheme for 3D to two‐dimensional (2D) rigid registration of coronary arteries extracted from preoperative image scan (3D) and a single segmented intraoperative x‐ray angio frame in frequency and spatial domains for real‐time angiography interventions by C‐arm fluoroscopy.Methods:Most existing rigid registration approaches require a close initialization due to the abundance of local minima and high complexity of search algorithms. The authorsˈ method eliminates this requirement by transforming the projections into translation‐invariant Fourier domain for estimating the 3D pose. For 3D rotation recovery, template Digitally Reconstructed Radiographs (DRR) as candidate poses of 3D vessels of segmented computed tomography angiography are produced by rotating the camera (image intensifier) around the DICOM angle values with a specific range as in C‐arm setup. The authors have compared the 3D poses of template DRRs with the segmented x‐ray after equalizing the scales in three domains, namely, Fourier magnitude, Fourier phase, and Fourier polar. The best rotation pose candidate was chosen by one of the highest similarity measures returned by the methods in these domains. It has been noted in literature that frequency domain methods are robust against noise and occlusion which was also validated by the authorsˈ results. 3D translation of the volume was then recovered by distance‐map based BFGS optimization well suited to convex structure of the authorsˈ objective function without local minima due to distance maps. A novel automatic x‐ray vessel segmentation was also performed in this study.Results:Final results were evaluated in 2D projection space for patient data; and with ground truth values and landmark distances for the images acquired with a solid phantom vessel. Results validate that rotation recovery in frequency domain is robust against differences in segmentations in two modalities. Distance‐map translation is successful in aligning coronary trees with highest possible overlap.Conclusions:Numerical and qualitative results show that single view rigid alignment in projection space is successful. This work can be extended with multiple views to resolve depth ambiguity and with deformable registration to account for nonrigid motion in patient data.
Calculation of dose distributions for 12 106Ru/106Rh ophthalmic applicator models with the PENELOPE Monte Carlo code
Authors: Hermida‐López M. 
Published: September 2013

Purpose:For decades,106Ru/106Rh ophthalmic applicators have been widely used to treat intraocular malignancies with good clinical outcomes. Determining the dosimetry of such applicators is challenging because of their spherical shape, the low range of emitted betas and the steep gradients involved. Furthermore, there is a lack of dose distribution data in the literature for some applicator models. It is crucial to understand the generated dose distributions to improve the treatment planning process. This study aims to calculate the dose distributions in water for 12 commercially available 106Ru/106Rh ophthalmic applicators.Methods:The applicators were modeled using the Monte Carlo (MC) code PENELOPE‐2008.1. A planar nonclinical applicator was also simulated. Depth‐dose profiles along the central axis and lateral dose profiles at several depths were calculated and compared with the available published measured and calculated data. In the absence of published data, measurements performed by the manufacturer were used.Results:For some applicators, the calculated results obtained in this work showed improved consistency with the available experimental data compared with previously published calculations. For others, the data calculated in this work represent the first published dose data.Conclusions:The MC code PENELOPE‐2008.1 can accurately calculate the dose distributions for106Ru/106Rh ophthalmic applicators. The obtained set of tabulated dose distribution values may be useful for quality assurance of treatment planning systems and as a reference for comparison with future measurements and calculations.
Power spectrum analysis of the x‐ray scatter signal in mammography and breast tomosynthesis projections
Authors: Sechopoulos Ioannis , Bliznakova Kristina , Fei Baowei 
Published: September 2013

Purpose:To analyze the frequency domain characteristics of the signal in mammography images and breast tomosynthesis projections with patient tissue texture due to detected scattered x‐rays.Methods:Acquisitions of x‐ray projection images of 19 different patient breasts were simulated using previously acquired volumetric patient images. Acquisition of these images was performed with a dedicated breast CT prototype system, and the images were classified into voxels representing skin, adipose, and glandular tissue with a previously validated automated algorithm. The classified three dimensional images then underwent simulated mechanical compression representing that which is performed during acquisition of mammography and breast tomosynthesis images. The acquisition of projection images of each patient breast was simulated using Monte Carlo methods with each simulation resulting in two images: one of the primary (non‐scattered) signal and one of the scatter signal. To analyze the scatter signal for both mammography and breast tomosynthesis, two projections images of each patient breast were simulated, one with the x‐ray source positioned at 0° (mammography and central tomosynthesis projection) and at 30° (wide tomosynthesis projection). The noise power spectra (NPS) for both the scatter signal alone and the total signal (primary + scatter) for all images were obtained and the combined results of all patients analyzed. The total NPS was fit to the expected power‐law relationship NPS(f) = k/f∧β and the results were compared with those previously published on the power spectrum characteristics of mammographic texture. The scatter signal alone was analyzed qualitatively and a power‐law fit was also performed.Results:The mammography and tomosynthesis projections of three patient breasts were too small to analyze, so a total of 16 patient breasts were analyzed. The values of β for the total signal of the 0° projections agreed well with previously published results. As expected, the scatter power spectrum reflected a fast drop‐off with increasing spatial frequency, with a reduction of four orders of magnitude by 0.1 lp/mm. The β values for the scatter signal were 6.14 and 6.39 for the 0° and 30° projections, respectively.Conclusions:Although the low‐frequency characteristics of scatter in mammography and breast tomosynthesis were known, a quantitative analysis of the frequency domain characteristics of this signal was needed in order to optimize previously proposed software‐based x‐ray scatter reduction algorithms for these imaging modalities.
Content‐based image retrieval of multiphase CT images for focal liver lesion characterization
Authors: Chi Yanling , Zhou Jiayin , Venkatesh Sudhakar K. , Tian Qi , Liu Jimin 
Published: September 2013

Purpose:Characterization of focal liver lesions with various imaging modalities can be very challenging in the clinical practice and is experience‐dependent. The authors’ aim is to develop an automatic method to facilitate the characterization of focal liver lesions (FLLs) using multiphase computed tomography (CT) images by radiologists.Methods:A multiphase‐image retrieval system is proposed to retrieve a preconstructed database of FLLs with confirmed diagnoses, which can assist radiologists’ decision‐making in FLL characterization. It first localizes the FLL on multiphase CT scans using a hybrid generative‐discriminative FLL detection method and a nonrigid B‐spline registration method. Then, it extracts the multiphase density and texture features to numerically represent the FLL. Next, it compares the query FLL with the model FLLs in the database in terms of the feature and measures their similarities using the L1‐norm based similarity scores. The model FLLs are ranked by similarities and the top results are finally provided to the users for their evidence studies.Results:The system was tested on a database of 69 four‐phase contrast‐enhanced CT scans, consisting of six classes of liver lesions, and evaluated in terms of the precision‐recall curve and the Bullˈs Eye Percentage Score (BEP). It obtained a BEP score of 78%. Compared with any single‐phase based representation, the multiphase‐based representation increased the BEP scores of the system, from 63%–65% to 78%. In a pilot study, two radiologists performed characterization of FLLs without and with the knowledge of the top five retrieved results. The results were evaluated in terms of the diagnostic accuracy, the receiver operating characteristic (ROC) curve and the mean diagnostic confidence. One radiologistˈs accuracy improved from 75% to 92%, the area under ROC curves (AUC) from 0.85 to 0.95 (p = 0.081), and the mean diagnostic confidence from 4.6 to 7.3 (p = 0.039). The second radiologistˈs accuracy did not change, at 75%, with AUC increasing from 0.72 to 0.75 (p = 0.709), and the mean confidence from 4.5 to 4.9 (p = 0.607).Conclusions:Multiphase CT images can be used in content‐based image retrieval for FLLˈs categorization and result in good performance in comparison with single‐phase CT images. The proposed method has the potential to improve the radiologists’ diagnostic accuracy and confidence by providing visually similar lesions with confirmed diagnoses for their interpretation of clinical studies.
Third ventricular enlargement in early stages of multiple sclerosis is a predictor of motor and neuropsychological deficits: a cross-sectional study
Authors: Müller Martin , Esser Regina , Kötter Katharina , Voss Jan , Müller Achim , Stellmes Petra 
Published: September 2013

ObjectivesWhether transcranal sonography (TCS) depicted third ventricular enlargement as a sign of brain atrophy is predictive for neuropsychological deficits in mildly affected patients with multiple sclerosis (MS).DesignCross-sectional study of a cohort of mildly diseased patients with MS.SettingNeurological MS outpatient clinic at a large teaching hospital in central Europe.ParticipantsFifty-four patients with MS (16 men, 38 women, mean age 40±10 years, mean disease duration 6±5 years; mean Expanded Disability Status Scale 2±1.3) and 33 healthy controls (12 men, 21 women; 38±11 years) underwent clinical examination, an assessment of the third ventricle width by means of TCS and the Brief Repeatable Battery of Neuropsychological tests for MS, the 25-Feet Foot Walk test, the 9-Hole PEG test, the Beck Depression Inventory and a quantitative fatigue assessment. Statistical analysis was performed with univariate correlation and thereafter by stepwise regression analysis.ResultsPatients’ mean third ventricular width (3.9±1.6 mm) was significantly wider compared to controls (3.4±0.8 mm). Using stepwise regression analysis models with age, MS duration, third ventricle width and quantitative fatigue assessment as baseline variables, an increasing third ventricle width significantly correlated with the target variables worsening of motor deficits (p<0.002), worsening of verbal recall (p<0.04) and of visual spatial recall (p<0.005). Severity of depression and of fatigue was unrelated to third ventricular width.ConclusionsIn this cohort of patients with MS with mild disease, third ventricular enlargement was indicative for motor deficits and cognitive impairment, even after considering fatigue as a relevant comorbidity. Third ventricular enlargement by means of TCS seems to be a useful, clinically meaningful parameter to stage patients’ disease severity. Follow-up studies must show whether an intraindividual future third ventricular increase indeed signals larger cognitive impairment.
Real time shift reporting by emergency physicians predicts overall ED performance
Authors: Husain Nadia , Bein Kendall J , Green Timothy C , Veillard Anne-Sophie , Dinh Michael M 
Published: September 2013

ObjectiveTo investigate factors associated with emergency physician perception of the shift and to determine whether these perceptions were predictors of overall daily emergency department (ED) performance indicators.MethodsThis was an observational study conducted at an inner city ED in New South Wales. Shift reports completed by the emergency physician in charge at clinical handover times between February and July 2012 were included. Variables collected by the shift report included (1) total number of patients in ED, (2) number of patients in the ED with length of stay (LOS) greater than 4 h, (3) number of admitted patients, (4) number of patients waiting to be seen by a doctor and (5) medical staffing levels. Outcomes of interest for this study were shift perception scores (1=very poor to 5=very good) and daily ED performance measures. Performance measures were the proportion of patients admitted or discharged from ED within 4 h (National Emergency Access Target, NEAT) and the percentage of inpatient admissions leaving ED within 8 h of ED arrival time.ResultsThe number of patients in ED with LOS >4 h (OR 0.83, 95% CI 0.79 to 0.87, p value <0.001) and number of patients waiting to be seen (OR 0.92, 95% CI 0.88 to 0.95, p value <0.001) were the factors most strongly associated with shift perception score. After adjustment, the mean NEAT performance improved 6% for each incremental increase in average shift perception score (β=0.06 95% CI 0.04 to 0.07, p<0.001).ConclusionsShift reports and shift perceptions by emergency physicians may be used to predict overall ED performance.
OP10 How do Women Living in Socioeconomically Contrasting Neighbourhoods Perceive the Relationship between their Neighbourhoods and Health? A Qualitative Study in Aleppo, Syria
Authors: Zaman S , Fouad F , Pless-Mulloli T , White M , Ahmad B 
Published: September 2013

BackgroundThere is substantial evidence from multilevel studies in high income countries that neighbourhood socioeconomic status (SES) influences health independent of individual SES characteristics. In comparison, few qualitative studies have explored lay knowledge of neighbourhood influence on health. We explored and compared views on how neighbourhoods influenced health in married women, from different socioeconomic positions and living in neighbourhoods of contrasting SES in Aleppo.MethodsA qualitative study was undertaken in April-May 2011 as part of a mixed-method study investigating the relationship between neighbourhood socioeconomic status and self-reported health (prior to the armed conflict in Aleppo). In-depth interviews were conducted with 27 married women. Respondents were asked how living in the neighbourhood influenced their health and whether anything disturbed them in their life in the neighbourhood. Thematic analysis was used.ResultsOnly a few high-income women living in high SES neighbourhoods perceived a direct link between neighbourhood characteristics and physical health. However, all respondents pointed to multiple physical and social neighbourhood characteristics that they perceived as stressors. Many respondents, irrespective of their neighbourhood SES, perceived the poor quality of the physical neighbourhood environment, especially from traffic congestion and waste, to influence their wellbeing. We found similarities in women’s views on perceived neighbourhood stressors based on household and neighbourhood socioeconomic status as well as ethnicity and religion. Irrespective of socioeconomic position, respondents from certain religious or ethnic minorities emphasised the importance to their wellbeing of living in neighbourhoods with a large population of a similar religious or ethnic composition. The majority of women living in poor neighbourhoods viewed poor quality housing and overcrowding as sources of stress.ConclusionOur findings support previous results from western nations. Overall this suggests that the influence of neighbourhood on wellbeing maybe a universal phenomenon. Religion represented an important ‘normative guideline’ in the way women perceived their neighbourhoods and their effect on wellbeing. This study offers a unique insight into mechanisms by which neighbourhoods influenced health and wellbeing of women before the armed conflict in Syria. Understanding the nature and causes of neighbourhood influences on health and health inequalities will be particularly important for urban and social renewal policies as Syria emerges from its present crisis. It will also have wider application for urban renewal in other nations.
PP14 Whole Grain intake Correlates in Young Adults
Authors: Kamar M , Evans Cel 
Published: September 2013

BackgroundWhole grain consumption has been linked to reduced risks of hypertension, diabetes, obesity, cardiovascular disease, and various types of cancer. Almost a third of UK adults and children do not consume whole grains at all, and as little as 5% of the population reach the recommended three portions per day. Little has been done to explore whole grain consumption correlates in the UK - with no studies on young adults. This age group has been found to be on the lower end of whole grain intake in studies at the national level. This study aimed to explore the awareness, consumption patterns, barriers and possible facilitators for whole grain consumption in a sample of UK young adults.MethodsParticipants were 20 students aged 20-35 years old of various ethnicities. Dietary patterns and awareness about whole grains were measured using picture-assisted 24-hour recalls followed by questionnaires. Focus group discussions were conducted, where awareness, barriers and facilitators for consumption were discussed. Participants were also educated on health benefits, available varieties, identification of whole grain products, and provided with sample products to try. After 2 weeks the participants were followed-up using picture-assisted 24-hour recalls and questionnaires.ResultsThe results of the study show an improvement in consumption, awareness of health benefits, identification, and acceptance of whole grain foods among participants at follow up by 0.25 servings/week, 41%, 50%, and 8.5% respectively. The majority of participants reported bread and cereal products to be their favourite varieties. The top barriers to whole grain consumption appeared to be: sensory properties, higher price, lower availability, and lack of awareness of health benefits. Suggested facilitators of consumption were educational campaigns, a standardised whole grain product stamp, price reductions and offers, and increased availability and varieties. Asian ethnicity, female gender, home eating, and healthier lifestyles were observed to be positively associated with some whole grain intake correlates, but with no statistical significance.ConclusionThis study identified barriers and facilitators to whole grain consumption in UK young adults. More research should address whole grain intake correlates and interventions. This would encourage governmental, health service, and industrial action to improve whole grain awareness, availability, and consumption.