Development of 3D Image Reconstruction Based on Untracked 2D Fetal Phantom Ultrasound Images using VTK MAHANI HAFIZAH, TAN KOK, EKO SUPRIYANTO Department of Clinical Science and Engineering University Technology of Malaysia UTM Skudai, 81310 Johor MALAYSIA wmhafizah@gmail.com http://www.biomedical.utm.my Abstract: - Three dimensional (3D) ultrasound image reconstruction based on two dimensional (2D) images has become a famous method for analyzing some anatomy related to abnormalities. 3D ultrasound image reconstruction system is required in order to view the specific part of the object and so that it can be used for analysis purpose. In this paper, 2D images of fetal phantom were taken by using untracked free-hand ultrasound system. Few sets of 2D images were taken with different number of slices and after some basic 2D image processing, 3D reconstruction is done by using surface rendering techniques by implementing contour filtering and marching cubes algorithm in Visual C++ 6.0 with Visualization Toolkit (VTK) toolbox. From the experiment, we can conclude that in order to reconstruct a better 3D image, the aid of tracking sensor is important. Besides, image processing need to be performed thoroughly by adding other detailed processing techniques so that noises can be fully removed. From the result also, it can be concluded that the marching cube algorithm can give a better result compare to contour filtering where marching cubes algorithm can generate higher intensity 3D image which can make user easy to detect inner part and edges of 3D images. The number of slices should also be increased to improve the accuracy of the 3D image constructed. Key-Words: - 2D ultrasound, 3D ultrasound, marching cubes, contour filtering, visualization toolkit (VTK) 1 Introduction Medical imaging is the technique used to create images of the human body for clinical purposes especially for analyzing some anatomy related to abnormalities. Some of the commonly used imaging techniques are ultrasound, CT, and MRI [1-2]. However, the major difference between the other medical imaging equipment and ultrasound is that it is safer, low cost, non-invasive and non-traumatic. This made the diagnostic ultrasound machine become more popular than the other diagnostic tools [3]. Diagnostic ultrasound is applied for obtaining images of almost the entire range of internal organs in the abdomen including genitourinary system which consists of kidneys, urinary bladder, urethra and reproductive system of male and female [4, 44 - 47]. However, conventional 2D ultrasound imaging has limitations in quantifying the volume of structures of interest in the body, because only a two dimensional frame is produced at a given time. Volume quantification is important in assessing the progression of disease and tracking progression of response to treatment. Thus, 3D ultrasound imaging has drawn great attention in recent years especially in high quality hospitals and medical centers [5–6]. The 3D ultrasound systems can be classified as tracked free-hand, untracked free-hand, mechanical assemblies, and 2D arrays [7-8]. In tracked free-hand systems, the operator holds an assembly composed of the transducer and an attachment, and manipulates it over the anatomy and 2D images are digitized as the transducer is moved. For untracked free-hand systems approach, the operator moves the transducer in a steady and regular motion while 2D images are digitized and in order to reconstruct a 3D image, a linear or angular spacing between digitized images is assumed. In mechanical localizers, the transducer is translated or rotated mechanically, while 2D ultrasound images are digitized at predefined spatial or angular intervals while 2D arrays generates a pyramidal pulse of ultrasound and processes the echoes to generate 3D information in real-time [9-12]. The 3D reconstruction process refers to the generation of a 3D image from a digitized set of 2D images and two approaches can be used which is either 3D surface model or voxel-based volume. Besides, the ability to visualize information in the 3D image depends critically on the rendering technique. Three basic types being used are surface-based viewing techniques, multi-plane viewing techniques and volume-based rendering techniques [13-14]. In this paper, 2D images were taken by using untracked free-hand system. Few sets of 2D images were taken with different number of slices and after some 2D image processing, 3D reconstruction is done WSEAS TRANSACTIONS on SIGNAL PROCESSING Mahani Hafizah, Tan Kok, Eko SupriyantoISSN: 1790-5052 145 Issue 4, Volume 6, October 2010
