Directional-TV algorithm for image reconstruction from limited-angular-range data

Investigation of image reconstruction from data collected over a limited-angular range in X-ray CT remains a topic of active research because it may yield insight into the development of imaging workflow of practical significance. This reconstruction problem is well-known to be challenging, however, because it is highly ill-conditioned. In the work, we investigate optimization-based image reconstruction from data acquired over a limited-angular range that is considerably smaller than the angular range in short-scan CT. We first formulate the reconstruction problem as a convex optimization program with directional total-variation (TV) constraints applied to the image, and then develop an iterative algorithm, referred to as the directional-TV (DTV) algorithm for image reconstruction through solving the optimization program. We use the DTV algorithm to reconstruct images from data collected over a variety of limited-angular ranges for breast and bar phantoms of clinical- and industrial-application relevance. The study demonstrates that the DTV algorithm accurately recovers the phantoms from data generated over a significantly reduced angular range, and that it considerably diminishes artifacts observed otherwise in reconstructions of existing algorithms. We have also obtained empirical conditions on minimal-angular ranges sufficient for numerically accurate image reconstruction with the DTV algorithm.     

Étude de faisabilité : l’utilisation de l’imagerie médicale en éducation thérapeutique en radiothérapie

PurposeAssess the feasibility of a randomized controlled trial (RCT) exploring the use of medical imaging as a therapeutic education (TPE) intervention in external radiation therapy.Materials and methodsExperimental feasibility trial of “RCT” type carried out in a single-center, between November 2019 and March 2020, following adult patients treated by thoracic radiotherapy. In addition to the information usually given, the experimental group benefited from an intervention consisting in the visualization of their own medical images using the open-source software “Stone of Orthanc”.ResultsForty-nine patients were recruited with a refusal rate of 8.16% (4/49). 20 patients were withdrawn from the study for health reasons (COVID), 10 for medical reasons. All the remaining 15 participants completed the process. Although not significant, the experimental group showed a median gain in the perception of knowledge compared to the control group (+ 1.9 (1.6 – 2.2)) vs (+ 1.4 (1.4 – 1.8)), as well as a decrease in scores related to anxiety (? 3.0 (?4.5 - (?2.0)) vs ? 1.0 (?5.0 - 0.0)) and emotional distress ((? 5.0 (? 7.5 - (? 3.5)) vs (? 2.0 (? 5.0 - (? 1.0)) A significant reduction (p = 0.043) is observed for the depression score ((? 2.0 (?3.0 - (?1.5)) vs (0.0 (0.0 – 0.0)).ConclusionThis study demonstrates the feasibility of the project, with promising preliminary results. Some adaptations in order to conduct a larger-scale RCT are highlighted.     

Reference values of postural balance in preschoolers: Age and gender differences for 4–5 years old Tunisian children

BackgroundPreschool age is a critical stage of postural balance development. Posturography normative data during this age are crucial for surveillance of postural balance and for the timely diagnosis of any dysfunction. The aim of this study was to provide normative data, specific to Tunisian preschoolers, according to age and gender, and to examine gender- and age-related differences in postural balance.Research questionAre there postural balance gender- and age-related differences in Tunisian preschoolers?MethodsThe study included 410 (205 boys and 205 girls) preschool children aged between 4- and 5-year-old selected within a large geographic area of Tunisia. Postural balance was assessed using a stabilometric platform under 4 sensory conditions. The mean center of pressure velocity (CoP-V) parameter was selected for analysis. Differences between gender and age groups were analysed using the Mann–Whitney U. Normative data were expressed in percentiles.ResultsSignificant gender effect was found in conditions where sensory inputs are most challenged with a significantly smaller mean CoP-V in girls compared to boys (p < 0.05). Moreover, 5-year-old children had significantly better postural balance than 4-year-old ones in almost all conditions (p < 0.05).SignificanceThe normative data established for Tunisian preschoolers provide useful comparative data for pediatricians, teachers and coaches for the early evaluation and monitoring of postural balance during this age. Gender and age-related differences should be considered in this population.