Date of Award

8-1-2012

Degree Name

Master of Science

Department

Biomedical Engineering

First Advisor

Chen, Ying(Ada)

Abstract

Objective: Breast cancer is one of the most worldwide cancers among women and in United States it is also the second leading cause of cancer related death among women. The earlier breast cancer is detected, the better the outcome of treatment will be. So early detect technique for breast cancer is crucial. However traditional mammography as a standard and important detection technique has its own disadvantage, like motion blur with X-tube movement and only 2D information offered. But Tomosynthesis as an alternative breast cancer detection technique can overcome these disadvantages effectively. That is the reason why more and more academic concerns are put on Tomosynthesis. This paper is to research the effects of different X-tube distributions for the reconstructed images quality, expecting to offer a reference to design imaging configuration for Tomosynthesis. The reconstructed algorithm used here is maximum Likelihood Expectation Maximization (MLEM) algorithm, considering the image quality reconstructed by MLEM is the best with regards to our simulated imaging system. Methods: Six X-tube distributions are simulated to generate the projection image. They are uniform parallel configuration, non-uniform parallel configuration (dense center), non-uniform parallel configuration (sparse center), uniform rectangle configuration, non-uniform rectangle configuration (dense near axis) and non-uniform rectangle configuration (sparse near axis). The impulse responses of these six imaging systems are studied. And a wire in each of these six imaging systems is simulated to evaluate imaging quality. The spatial resolutions of three directions (xyz) in the reconstructed images are compared. Results: Compared with parallel and Rectangle configurations, Rectangle ones can enhance the contrast between object and background, increase the sharpness of object. Compared with uniform and non-uniform configurations, the contrasts are similar but the object sharpness from uniform configuration is between those from two non-uniform configurations. Key words: Tomosynthesis, X-tube distribution, uniform, non-uniform, parallel, rectangle, MLEM

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