Mapping the timeliness of routine childhood vaccination in The Gambia: A spatial modelling study.

INTRODUCTION: Timeliness of routine vaccination shapes childhood infection risk and thus is an important public health metric. Estimates of indicators of the timeliness of vaccination are usually produced at the national or regional level, which may conceal epidemiologically relevant local heterogeneities and makeitdifficultto identify pockets of vulnerabilities that could benefit from targeted interventions. Here, we demonstrate the utility of geospatial modelling techniques in generating high-resolution maps of the prevalence of delayed childhood vaccination in The Gambia. To guide local immunisation policy and prioritize key interventions, we also identified the districts with a combination of high estimated prevalence and a significant population of affected infants. METHODS: We used the birth dose of the hepatitis-B vaccine (HepB0), third-dose of the pentavalent vaccine (PENTA3), and the first dose of measles-containing vaccine (MCV1) as examples to map delayed vaccination nationally at a resolution of 1 × 1-km2 pixel. We utilized cluster-level childhood vaccination data from The Gambia 2019-20 Demographic and Health Survey. We adopted a fully Bayesian geostatistical model incorporating publicly available geospatial covariates to aid predictive accuracy. The model was implemented using the integrated nested Laplace approximation-stochastic partial differential equation (INLA-SPDE) approach. RESULTS: We found significant subnational heterogeneity in delayed HepB0, PENTA3 and MCV1 vaccinations. Specificdistricts in the central and eastern regions of The Gambia consistentlyexhibited the highest prevalence of delayed vaccination, while the coastal districts showed alower prevalence forallthree vaccines. We also found that districts in the eastern, central, as well as in coastal parts of The Gambia had a combination of high estimated prevalence of delayed HepB0, PENTA3 and MCV1 and a significant population of affected infants. CONCLUSIONS: Our approach provides decision-makers with a valuable tool to better understand local patterns of untimely childhood vaccination and identify districts where strengthening vaccine delivery systems could have the greatest impact

The effect of delayed scanning of storage phosphor plates on occlusal caries detection

PubMed ID: 22282506Objective: The aim of this study was to determine (1) the effect of various scan delays on pixel intensity measurements and (2) the diagnostic accuracy of occlusal caries detection. Methods: 72 non-cavitated extracted human permanent molar teeth with sound and carious occlusal surfaces were radiographed using the DIGORA ® storage phosphor plates (SPPs) (Soredex Corporation, Helsinki, Finland). Plates were scanned immediately and 10 min, 30 min, 60 min and 120 min after exposure. Three different plates were used for each scan delay. An aluminium (Al) wedge was used to evaluate the change in mean grey values (MGVs) for scan delays. Diagnostic accuracy for occlusal caries detection was performed by scoring all the digital images. The true presence of caries was determined by stereomicroscopy. Comparison of MGVs of the Al wedge for immediate and delayed scans was made using repeated measures analysis of variance (ANOVA) and Tukey-Kramer tests. The accuracy was expressed as the area under the receiver operating characteristics curves (A z). A zs were compared using two-way ANOVA and t-tests. Kappa was used to measure inter and intraobserver agreement. Results: The mean A zs of immediately scanned plates were higher than the A zs of plates scanned with four different delays (p < 0.05). The A z of immediately scanned images was significantly higher than the A zs of images with 60 min and 120 min scan delays (p < 0.05) but not for 10min and 30min delays (p > 0.05). MGVs of immediately scanned plates were significantly higher than the plates scanned with four different delays (p < 0.05). Agreement decreased with increasing scan delays. Conclusion: Scanning of DIGORA SPPs should not be delayed beyond 30min for accurate occlusal caries diagnosis. © 2012 The British Institute of Radiology

Perceptibility curve test for digital radiographs before and after application of various image processing algorithms

WOS: 000251682300008PubMed ID: 18033946Objectives: The aim of the present study was to compare digital radiographs before and after the application of various digital image enhancement methods by means of a perceptibility curve (PC) test. Methods: Radiographs of an aluminium test object containing holes with sizes ranging from 0.5 mm to 1.5 mm were exposed at nine time settings, ranging from 0.05 s to 3.2 s using Digora(R) (Soredex, Helsinki, Finland) storage phosphor system. Original digital images were then enhanced and displayed in colour-coded, contrast- and brightness-enhanced, histogram-equalized and negative modes. Thus, five series of images were created. Eight observers independently evaluated all of the images in the same random order and under the same viewing conditions. The object detail with the lowest perceptible contrast was recorded for each observer and each image type. Modified PCs were plotted according to the mean observer data. Repeated-measures ANOVA was used to compare the PCs and the perceptible number of details in original and enhanced images for each exposure (P = 0.05). The Bonferroni/Dunn test was used to identify statistical differences among the groups. Results: Histogram equalization showed the maximum number of perceptible details in both the lowest optimal exposure time and the widest exposure range (P 0.05). Conclusion: Histogram-equalization enhancement of Digora(R) images demonstrated subjectively superior image quality, followed by contrast and brightness enhancement