Lai Khin Wee

Multipurpose contrast enhancement on epiphyseal plates and ossification centers for bone age assessment

BackgroundThe high variations of background luminance, low contrast and excessively enhanced contrast of hand bone radiograph often impede the bone age assessment rating system in evaluating the degree of epiphyseal plates and ossification centers development. The Global Histogram equalization (GHE) has been the most frequently adopted image contrast enhancement technique but the performance is not satisfying. A brightness and detail preserving histogram equalization method with good contrast enhancement effect has been a goal of much recent research in histogram equalization. Nevertheless, producing a well-balanced histogram equalized radiograph in terms of its brightness preservation, detail preservation and contrast enhancement is deemed to be a daunting task.MethodIn this paper, we propose a novel framework of histogram equalization with the aim of taking several desirable properties into account, namely the Multipurpose Beta Optimized Bi-Histogram Equalization (MBOBHE). This method performs the histogram optimization separately in both sub-histograms after the segmentation of histogram using an optimized separating point determined based on the regularization function constituted by three components. The result is then assessed by the qualitative and quantitative analysis to evaluate the essential aspects of histogram equalized image using a total of 160 hand radiographs that are implemented in testing and analyses which are acquired from hand bone online database.ResultFrom the qualitative analysis, we found that basic bi-histogram equalizations are not capable of displaying the small features in image due to incorrect selection of separating point by focusing on only certain metric without considering the contrast enhancement and detail preservation. From the quantitative analysis, we found that MBOBHE correlates well with human visual perception, and this improvement shortens the evaluation time taken by inspector in assessing the bone age.ConclusionsThe proposed MBOBHE outperforms other existing methods regarding comprehensive performance of histogram equalization. All the features which are pertinent to bone age assessment are more protruding relative to other methods; this has shorten the required evaluation time in manual bone age assessment using TW method. While the accuracy remains unaffected or slightly better than using unprocessed original image. The holistic properties in terms of brightness preservation, detail preservation and contrast enhancement are simultaneous taken into consideration and thus the visual effect is contributive to manual inspection.

An artifacts removal post-processing for epiphyseal region-of-interest (EROI) localization in automated bone age assessment (BAA)

BackgroundSegmentation is the most crucial part in the computer-aided bone age assessment. A well-known type of segmentation performed in the system is adaptive segmentation. While providing better result than global thresholding method, the adaptive segmentation produces a lot of unwanted noise that could affect the latter process of epiphysis extraction.MethodsA proposed method with anisotropic diffusion as pre-processing and a novel Bounded Area Elimination (BAE) post-processing algorithm to improve the algorithm of ossification site localization technique are designed with the intent of improving the adaptive segmentation result and the region-of interest (ROI) localization accuracy.ResultsThe results are then evaluated by quantitative analysis and qualitative analysis using texture feature evaluation. The result indicates that the image homogeneity after anisotropic diffusion has improved averagely on each age group for 17.59%. Results of experiments showed that the smoothness has been improved averagely 35% after BAE algorithm and the improvement of ROI localization has improved for averagely 8.19%. The MSSIM has improved averagely 10.49% after performing the BAE algorithm on the adaptive segmented hand radiograph.ConclusionsThe result indicated that hand radiographs which have undergone anisotropic diffusion have greatly reduced the noise in the segmented image and the result as well indicated that the BAE algorithm proposed is capable of removing the artifacts generated in adaptive segmentation.

Performance metrics for active contour models in image segmentation

Image segmentation is one of the significant techniques in image processing to distinguish desired parts from its background for further analysis. It provides visual means for inspection of anatomical structure of human body, identification of disease, tracking of its development and input for surgical planning and simulation. Active contour models are regarded as promising and vigorously research model-based approach to computer assisted medical image analysis. However, it is not trivial to assess whether one segmentation algorithm performs more superior than the other. Therefore, a systematic assessment tool is designed and implemented to examine all the important aspects of active contour models. Meanwhile, a novel supervised evaluator including analytical method and empirical methods are proposed to acts as objective evaluator. The obtained results highlighted both the strengths and limitations of the studied active contour models. A proper area usage of each active contour model is also suggested at the end of this paper.

Synthesis of a Nano-Silver Metal Ink for Use in Thick Conductive Film Fabrication Applied on a Semiconductor Package

The success of printing technology in the electronics industry primarily depends on the availability of metal printing ink. Various types of commercially available metal ink are widely used in different industries such as the solar cell, radio frequency identification (RFID) and light emitting diode (LED) industries, with limited usage in semiconductor packaging. The use of printed ink in semiconductor IC packaging is limited by several factors such as poor electrical performance and mechanical strength. Poor adhesion of the printed metal track to the epoxy molding compound is another critical factor that has caused a decline in interest in the application of printing technology to the semiconductor industry. In this study, two different groups of adhesion promoters, based on metal and polymer groups, were used to promote adhesion between the printed ink and the epoxy molding substrate. The experimental data show that silver ink with a metal oxide adhesion promoter adheres better than silver ink with a polymer adhesion promoter. This result can be explained by the hydroxyl bonding between the metal oxide promoter and the silane grouping agent on the epoxy substrate, which contributes a greater adhesion strength compared to the polymer adhesion promoter. Hypotheses of the physical and chemical functions of both adhesion promoters are described in detail.

Comparison studies of 2D and 3D ultrasound biparietal diameter for gestational age estimation

Accurate determination of gestational age is fundamental to fetal growth assessment, either clinically or by ultrasound evaluation. The antenatal measurement of the fetal biparietal diameter (BPD) by ultrasound has been used to predict fetal gestational age. The performance of conventional two-dimensional (2D) ultrasonograhpy (US) measurement and proposed Visualization toolkit, VTK programmable interactive three-dimensional (3D) for gestational age prediction is investigated in this paper. Data has been acquired in the form of video clip and DICOM file. Three-dimensional BPD reconstructions were visualized using open-source object-oriented Visualization toolkit, VTK. Ten trial measurements were taken for each method. Descriptive analysis of both UTV 380 and DICOM were calculated. Computed mean and standard deviation for both measurements are 47.326±0.643345mm (UTV 380) and 47.099±0.377343mm (DICOM). Computed mean and standard deviation for 2D measurement is 46.290±0.455705mm. Using 3D volume acquisition, it is feasible to perform and interpret a structural survey with higher accuracy in which a 2D survey is performed. Further research is necessary to standardize the acquisition of volumes to minimize artifacts and produce uniform images.

Color morphology and segmentation of the breast thermography image

Breast cancer is one of the most feared cancers among women due its high incidence in females around the world. The screening tools that are used for breast cancer detection are mammogram, ultrasound, MRI, CT-scan, PET and thermogram. Although mammogram is considered as the gold standard screening tool, this procedure is invasive, expensive, time consuming and causes physical discomfort to the patient. Therefore, to overcome this problem, high interest has been given to thermogram, a non-ionizing and non-contact procedure. However, the absence of clear edges of breasts and low contrast may cause difficulty to analyze the thermogram. This study proposes a pre-processing method to detect breast and body boundaries to eliminate unwanted area and to extract colors in thermogram image. This pre-processing procedure is a technique done before the data is used for feature extraction and image classification process.

Generic computing of enhanced speckle reduction on low end ultrasound machine images

Due to the emergence of microelectronics, ultrasound diagnostic machine can now be manufactured at low cost. The affordability of low cost ultrasound diagnostic machine is of utter importance in allowing wider exposure of ultrasound technology to the general public. Nonetheless, in comparison with international standard requirements, the quality of images from low cost ultrasound machine is still lacking. Furthermore, the evaluation of the quality is subjective and the process is tedious. In this paper, an enhanced processing of ultrasound images using de-speckle diffusion method is proposed and the result is evaluated quantitatively on aspects such as vertical and horizontal distance accuracy, axial and lateral resolution, near field distance, penetration depth and high scatter accuracy. It comprises of the directions north, south, east and west, and the average is taken into calculation by utilizing the instantaneous coefficient of variation (ICOV) method. Algorithms are verified according to its performance in speckle reduction and edge preservation based on root mean square error (RMSE), signal-to-noise ratio (SNR) and peak signal-to-noise ratio (PSNR). The result indicates that de-speckle diffusion is more robust compared to adaptive speckle reduction method. The results obtained proved that the proposed technique could greatly improve the low cost ultrasound image quality.

Comparative studies of two dimensional and three dimensional ultrasonic nuchal translucency in trisomy assessments.

Current two-dimensional (2D) ultrasonic marker measurements are inherent with intra- and inter-observer variability limitations. The objective of this paper is to investigate the performance of conventional 2D ultrasonic marker measurements and proposed programmable interactive three-dimensional (3D) marker evaluation. This is essentially important to analyze that the measurement on 3D volumetric measurement possesses higher impact and reproducibility vis-à-vis 2D measurement. Twenty three cases of prenatal ultrasound examination were obtained from collaborating hospital after Ethical Committees approval. The measured 2D ultrasonic marker is Nuchal Translucency or commonly abbreviated as NT. Descriptive analysis of both 2D and 3D ultrasound measurement were calculated. Three trial measurements were taken for each method. Both data were tested with One-Sample Kolmogorov-Smirnov Test and results indicate that markers measurements were distributed normally with significant parametric values at 0.621 and 0.596 respectively. Computed mean and standard deviation for both measurement methods are 1.4495 ± 0.46490 (2D) and 1.3561 ± 0.50994 (3D). ANOVA test shows that computerized 3D measurements were found to be insignificantly different from the mean of conventional 2D at the significance level of 0.05. With Pearsons correlation coefficient value or R = 0.861, the result proves strong positive linear correlation between 2D and 3D ultrasonic measurements. Reproducibility and accuracy of 3D ultrasound in NT measurement was significantly increased compared with 2D B-mode ultrasound prenatal assessment. 3D reconstructed imaging has higher clinical values compare to 2D ultrasound images with less diagnostics information.

An object-oriented approach of generic diffusion computing for three dimensional ultrasound volumetric images

Medical image information representation using two dimensional image planes have major drawbacks on the grounds that the there are technical constrains in providing the optimized spatial orientation and physical limitations. In comparison, three dimensional imaging shows higher degree of versatility in clinical application. Conventional anisotropic diffusion and speckle removal might have promising performance on 2D ultrasonic images, but it is not effective in 3D ultrasonic images. In this paper, we have developed extension algorithms for 3D diffusion in ultrasonic volume rendering using open source visualization toolkits. Investigations have been conducted on 3D volume rendering based on visualization toolkit (VTK) generic computing and the simulation results were compared with ordinary 2D diffusion in 3D ultrasonic image. Obstructive effect was eliminated with the proposed technique by conserving information between neighboring 2D slices. The experimental results show the significant improvement of 3D diffusion on 3D ultrasound volume rendering.