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25 April 2000 Effect of scatter radiation on image noise in cone-beam CT
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Cone beam CT has a capability of 3-dimensional imaging of large volumes with isotropic resolutions, and has a potentiality of 4-dimensional imaging (dynamic volume imaging) because cone beam CT acquires a large volume data with one rotation of X-ray tube-detector pair. However, one of the potential drawbacks with cone beam CT is larger amount of scattered X-rays. These X-rays may enhance the noise in reconstructed images, and thus affect low contrast detectability. The aim of this work was to estimate scatter fractions and effects of scatter on image noise, and was to seek methods of improving image quality in cone beam CT. First we derived a relationship between the noises in reconstructed image and in X-ray intensity measurement. Then we estimated scatter to primary ratios in X-ray measurements, using a Monte Carlo simulation. From these we estimated image noise in clinical relevant conditions. The results showed that scatter radiation made a substantial contribution to the image noise. However focused collimators improved it, because they decreased scatter radiation drastically while keeping the primary radiation nearly the same level. A conventional grid also improved image noise though the improvement was less than that of focused collimators.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Masahiro Endo, Takanori Tsunoo, and Nobuyuki Nakamori "Effect of scatter radiation on image noise in cone-beam CT", Proc. SPIE 3977, Medical Imaging 2000: Physics of Medical Imaging, (25 April 2000);


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