3D bronchial tree model and fractal analysis as tools for the performance evaluation of different CT acquisition/reconstruction schemes

摘要

We present an algorithm for the construction of a 3D bronchial tree representation based on an asymmetric dichotomy model proposed by Weibel. The model has a total of ten branch generations and three independent parameters for each branch. The bronchial tree model is constructed by dividing each branch of a generation into two subbranches, except for the first few generations where some branches divided into three subbranches. The bronchial tree model is used as a testground to simulate different CT acquisition/reconstruction schemes and examine the role of CT parameters, such as slice thickness and overlap/spacing, on the measurement of fractal properties of the lung. A digital version of the model with high resolution (0.2 mm/pix) is created first. Acquisition schemes are then simulated by dividing this high resolution version of the model into cross-sections and summing one or more cross- sections to form a series of 2D slices. Three acquisition schemes are simulated by choosing different ways to generate these 2D slices. To reconstruct the 3D bronchial tree structure from a series of 2D slices, interpolation is applied between the 2D slices to recover the original volume. Two types of interpolations are used here: (1) slice repetition (2) linear interpolation. Fractal measures of the 3D bronchial tree structure are estimated from the reconstructed images and compared with the same measures from the high resolution model.