Abstract
The purpose of this study is to investigate the impacts of added filtration on the contrast-detail detectability of a digital X-ray imaging system for small animal studies. A digital X-ray imaging system specifically designed for small animal studies was used. This system is equipped with a micro X-ray source with a tungsten target and a beryllium window filtration and a CCD-based digital detector. Molybdenum filters of 0 mm, 0.02 mm, and 0.05 mm in thickness were added. The corresponding X-ray spectra and contrast-detail detectabilities were measured using two phantoms of different thicknesses simulating breast tissue under different exposures. The added Mo filters reduced the low-energy as well as the high-energy photons, hence providing a narrowband for imaging quality improvement. In the experiments with a 1.15 cm phantom, the optimal image detectability was observed using 22 kVp and the 0.05 mm Mo filter. With the 2.15 cm phantom, the best detectability was obtained with 22 kVp and the 0.02 mm Mo filter. Our experiments showed that appropriate filtrations could reduce certain low- and high-energy components of X-ray spectra which have limited contributions to image contrast. At the same time, such filtration could improve the contrast-detail detectability, particularly at relatively low kVp and high filtration. Therefore, optimal image quality can be obtained with the same absorbed radiation dose by the subjects when appropriate filtration is used.
Highlights
When X-ray images are acquired, both patient radiation dose and image quality should be considered
The contrast-detail curves using the 1.15 cm and the 2.15 cm phantoms are given in Figures 5 and 6, respectively
Mo filters of different thicknesses were used in a digital X-ray imaging system for small animals research
Summary
When X-ray images are acquired, both patient radiation dose and image quality should be considered. Low-energy X-ray photons of an entrance spectrum penetrate tissue poorly and may not reach the image detector for useful diagnostic information. These attenuated X-ray photons only contribute to patient’s radiation dose and should be selectively removed from the X-ray beam by adding appropriate filtration between the X-ray source and the patients. Appropriate filtration can remove low and high-energy photons in the X-ray beam. The material and thickness of filters need to be carefully selected to satisfy both patient radiation dose and image quality considerations so that good performance of an X-ray imaging system can be achieved [1, 2]
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