Chest CT at a dose below 0.3 mSv : impact of iterative reconstruction on image quality and lung analysis

Le nombre d'examens tomodensitométriques (Computed Tomography, CT) effectués chaque année étant en constante augmentation, différentes techniques d'optimisation, dont les algorithmes de reconstruction itérative permettant de réduire le bruit tout en maintenant la résolution spatiale, ont étés développées afin de réduire les doses délivrées. Le but de cette étude était d'évaluer l'impact des algorithmes de reconstruction itérative sur la qualité image à des doses effectives inférieures à 0.3 mSv, comparables à celle d'une radiographie thoracique. Vingt CT thoraciques effectués à cette dose effective ont été reconstruits en variant trois paramètres: l'algorithme de reconstruction, rétroprojection filtrée versus reconstruction itérative iDose4; la matrice, 5122 versus 7682; et le filtre de résolution en densité (mou) versus spatiale (dur). Ainsi, 8 séries ont été reconstruites pour chacun des 20 CT thoraciques. La qualité d'image de ces 8 séries a d'abord été évaluée qualitativement par deux radiologues expérimentés en aveugle en se basant sur la netteté des parois bronchiques et de l'interface entre le parenchyme pulmonaire et les vaisseaux, puis quantitativement en utilisant une formule de merit, fréquemment utilisée dans le développement de nouveaux algorithmes et filtres de reconstruction. La performance diagnostique de la meilleure série acquise à une dose effective inférieure à 0.3 mSv a été comparée à celle d'un CT de référence effectué à doses standards en relevant les anomalies du parenchyme pulmonaire. Les résultats montrent que la meilleure qualité d'image, tant qualitativement que quantitativement a été obtenue en utilisant iDose4, la matrice 5122 et le filtre mou, avec une concordance parfaite entre les classements quantitatif et qualitatif des 8 séries. D'autre part, la détection des nodules pulmonaires de plus de 4mm étaient similaire sur la meilleure série acquise à une dose effective inférieure à 0.3 mSv et le CT de référence. En conclusion, les CT thoraciques effectués à une dose effective inférieure à 0.3 mSv reconstruits avec iDose4, la matrice 5122 et le filtre mou peuvent être utilisés avec confiance pour diagnostiquer les nodules pulmonaires de plus de 4mm.

Anatomical UV Exposure in French Outdoor Workers.

BACKGROUND: Solar ultraviolet has been recognized as the main causative factor for skin cancer and is currently classified as a carcinogenic agent by International Agency for Research on Cancer. METHOD: Results from a previous phone survey conducted in 2012 in France were used to assess exposure conditions to sun among outdoor workers. Satellite data were used in combination with an exposure model to assess anatomical exposure. RESULT: The yearly median exposure of the outdoor worker population is 77  kJ/m2 to 116  kJ/m2. Road workers, building workers, and gardeners are the more exposed. About 70% of the yearly dose estimate is due to the cumulative summer and spring exposures. CONCLUSIONS: This study highlights the role of individual factors in anatomical exposure and ranks the most exposed body parts and outdoor occupations. Prevention messages should put emphasis on spring exposure, which is an important contributor to the yearly dose.

Professional trajectories, individual characteristics and staying satisfied and healthy

Staying satisfied and healthy in the face of a complex and uncertain professional world is a priority for individuals. This article examines the contribution of personality traits, career adaptability, and prior well-being as predictors of well-being over 1 year in four different professional trajectory groups: those who remained employed, those who experienced a professional change, those who moved from unemployment to employment, and those who remained unemployed. Results show meaningful differences between these groups in terms of well-being over 1 year. Employed individuals have higher life satisfaction and self-rated health than unemployed individuals. Regaining employment contributes to improved well-being. Different professional situations correspond to varying levels of career adaptability, suggesting it may be a precursor for career changes. Personality traits and career adaptability predict well-being over time, but the strongest predictor of future well-being is prior well-being. Results are discussed in light of career development, personality, and well-being theory.

Image quality in CT: From physical measurements to model observers.

Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment.

Identifying Individual T Cell Receptors of Optimal Avidity for Tumor Antigens.

Cytotoxic T cells recognize, via their T cell receptors (TCRs), small antigenic peptides presented by the major histocompatibility complex (pMHC) on the surface of professional antigen-presenting cells and infected or malignant cells. The efficiency of T cell triggering critically depends on TCR binding to cognate pMHC, i.e., the TCR-pMHC structural avidity. The binding and kinetic attributes of this interaction are key parameters for protective T cell-mediated immunity, with stronger TCR-pMHC interactions conferring superior T cell activation and responsiveness than weaker ones. However, high-avidity TCRs are not always available, particularly among self/tumor antigen-specific T cells, most of which are eliminated by central and peripheral deletion mechanisms. Consequently, systematic assessment of T cell avidity can greatly help distinguishing protective from non-protective T cells. Here, we review novel strategies to assess TCR-pMHC interaction kinetics, enabling the identification of the functionally most-relevant T cells. We also discuss the significance of these technologies in determining which cells within a naturally occurring polyclonal tumor-specific T cell response would offer the best clinical benefit for use in adoptive therapies, with or without T cell engineering.

Optimization of Radiation Dose and Image Quality in Musculoskeletal CT: Emphasis on Iterative Reconstruction Techniques (Part 1).

Computed tomography (CT) is a modality of choice for the study of the musculoskeletal system for various indications including the study of bone, calcifications, internal derangements of joints (with CT arthrography), as well as periprosthetic complications. However, CT remains intrinsically limited by the fact that it exposes patients to ionizing radiation. Scanning protocols need to be optimized to achieve diagnostic image quality at the lowest radiation dose possible. In this optimization process, the radiologist needs to be familiar with the parameters used to quantify radiation dose and image quality. CT imaging of the musculoskeletal system has certain specificities including the focus on high-contrast objects (i.e., in CT of bone or CT arthrography). These characteristics need to be taken into account when defining a strategy to optimize dose and when choosing the best combination of scanning parameters. In the first part of this review, we present the parameters used for the evaluation and quantification of radiation dose and image quality. In the second part, we discuss different strategies to optimize radiation dose and image quality at CT, with a focus on the musculoskeletal system and the use of novel iterative reconstruction techniques.

Complications After Laparoscopic Roux-en-Y Gastric Bypass in 1573 Consecutive Patients: Are There Predictors?

BACKGROUND: Roux-en-Y gastric bypass (RYGBP), one of the commonest performed bariatric procedures, remains a technically challenging operation associated with significant morbidity in high-risk patients. This study was conducted in order to identify predictors of complications after laparoscopic RYGBP. METHODS: Our prospectively established database has been assessed to review 30-day and in-hospital complications graded according to a validated scoring system (Clavien-Dindo) and separated into minor (Clavien-Dindo I-IIIa) and major (Clavien-Dindo IIIb-IV) complications. Patient- and procedure-related factors were analyzed using univariate analysis. Significant factors associated with morbidity were introduced into a multivariate analysis to identify independent predictors. RESULTS: Between 1999 and 2012, 1573 patients underwent laparoscopic RYGBP, 374 male and 1199 female. Mean age was 41 years, and mean body mass index (BMI) was 44.5 kg/m(2). One hundred fifty-nine procedures were reoperations. One hundred fifty (9.5 %) patients developed at least one complication, and 43 (2.7 %) had major complications, leading to death in one case (0.06 %). Risk factors for morbidity were male gender (p = 0.006) and overall experience of the team (p < 0.0001). Prolonged 3-day antibiotic therapy was associated with significantly reduced overall (p < 0.0001) and major (p = 0.005) complication rates. Major complications were associated with smoking (p = 0.016). CONCLUSIONS: The most significant individual risk factors for early complications after RYGBP are male gender, limited surgical experience, and single dose of antibiotics. RYGBP should be performed by experienced teams. Smoking should be discontinued before surgery. Prolonged antibiotic therapy could be considered, especially if a circular stapled gastrojejunostomy is performed with the anvil introduced transorally.