Development of X-ray phase contrast imaging techniques for medical diagnostics: optimization of the method and implementation with new X-ray sources
Over the last years, the application of X-ray phase contrast imaging (PCI) techniques to biomedical imaging has attracted a vivid interest in the field of medical diagnostics. The unprecedented enhancement of the contrast that this new imaging modality may provide suggests the potential of overcoming the intrinsic limitations of standard radiology in the examination of soft tissues. PCI may allow observing contrast due to the phase modulation of X-rays, even if the amplitude (i.e. absorption) modulation is weak or absent, with a dose to the tissues similar or even reduced compared to conventional absorption radiography.
The aim of this research is to optimize PCI techniques by studying in-vitro and in-vivo relevant medical diagnostics cases and to compare the several PCI methods (crystal-, propagation-, grating-based techniques) for specific clinical applications. Presently we are focused on two major areas that are breast cancer and osteoarthritis detection, but other medical applications could be considered in the future. In previous works, the capability of PCI to differentiate malignant tissue from normal tissue in whole breast samples has been demonstrated and high resolution phase contrast tomography has been explored for the depiction of structural details and the visualization of pathologic features in relatively thick cartilage samples using different PCI methods.
Major aspects of the present and future research activity include image quality, diagnostic accuracy, and radiation dose exposure. Moreover, given the strong background in clinical diagnostic radiology, we aim to develop technical prerequisites (hardware, software) for an implementation into patient care. Highly collimated and partially coherent synchrotron radiation is used as gold standard radiation for the development of PCI, with the objective of implementing these techniques at compact high brilliant and high energetic X-ray sources presently under development around the word and in near future available in Munich.
This research is performed in the framework of a multidisciplinary team of complementary expertise formed by physicists of the LMU / TU (Munich) and of the European Synchrotron Radiation Facility (ESRF, Grenoble, France) and clinical partners at the department of clinical radiology (LMU, Munich).
Contribution to IMPRS curriculum:
Physical techniques in biomedicine
Lecturer: Paola Coan (2 SWS or block of lectures)
This course focuses on the description of the physical basics for biomedical diagnostics. The fundamentals of X-ray generation, interaction and detection in diagnostics imaging are introduced. The main concepts for the assessment of the performance of a detection apparatus (line-spread function, modulation transfer function, noise power spectrum, detective quantum efficiency) are described within the theory of linear-systems. The principal parameters (contrast, signal-to-noise ratio) for the evaluation of the image quality for digital systems are discussed. An overview of the principle imaging modalities used in biomedical diagnostics is given. The radioprotection aspects as well as the main quantities describing the radiobiological effects of the radiation on tissues are discussed. As a complementary part, some of the most advanced X-ray imaging techniques under development in recent years are presented.