X-ray Phase Contrast Imaging with Hybrid Semiconductor Pixel Detectors

AbstraktAbstract

This PhD. Thesis is devoted to the development of novel radiation imaging approaches based on the application of hybrid pixel semiconductor detectors. Phase contrast imaging, a technique utilizing the wave nature of ionizing radiation for image formation, is currently considered as a most promising way leading to soft tissue contrast improvement and dose reduction in X-ray radiography. Present approaches however put very stringent requirements on experimental instrumentation (the need of highly-brilliant X-ray sources provided namely by large synchrotron facilities, dedicated X-ray optics and elaborated image acquisition procedures such as multiple object exposure) which are usually not suitable for practical imaging applications. In frame of this Thesis, a novel technique based on the combination of a laboratory compact X-ray tube and the hybrid pixel detector of the Medipix type in a table-top setup was developed. The technique provides the possibility to perform simultaneous single-exposure acquisition of the phase-gradient, of the conventional absorption image and alternatively also of the image based on the local scattering power of the sample. In the context of this work a laboratory setup for the proposed approach was built up, including the design of dedicated gratings, optimization of the detector performance and development of data-processing techniques for retrieval of images formed by the different contrast mechanism (phase changes, attenuation). This novel technique has been successfully used for X-ray imaging with testing objects showing good reliability of the method as well as with more complex samples demonstrating the potential of the technique for application in biology, non-destructing testing and in the future also in medicine.

This PhD. Thesis is devoted to the development of novel radiation imaging approaches based on the application of hybrid pixel semiconductor detectors. Phase contrast imaging, a technique utilizing the wave nature of ionizing radiation for image formation, is currently considered as a most promising way leading to soft tissue contrast improvement and dose reduction in X-ray radiography. Present approaches however put very stringent requirements on experimental instrumentation (the need of highly-brilliant X-ray sources provided namely by large synchrotron facilities, dedicated X-ray optics and elaborated image acquisition procedures such as multiple object exposure) which are usually not suitable for practical imaging applications. In frame of this Thesis, a novel technique based on the combination of a laboratory compact X-ray tube and the hybrid pixel detector of the Medipix type in a table-top setup was developed. The technique provides the possibility to perform simultaneous single-exposure acquisition of the phase-gradient, of the conventional absorption image and alternatively also of the image based on the local scattering power of the sample. In the context of this work a laboratory setup for the proposed approach was built up, including the design of dedicated gratings, optimization of the detector performance and development of data-processing techniques for retrieval of images formed by the different contrast mechanism (phase changes, attenuation). This novel technique has been successfully used for X-ray imaging with testing objects showing good reliability of the method as well as with more complex samples demonstrating the potential of the technique for application in biology, non-destructing testing and in the future also in medicine.