Virtual histology of dried and mummified biological samples by laboratory phase-contrast tomography

摘要

Ancient remains from humans, animals and plants hold valuable information about our history. X-ray imagingmethods are often, because of their non-destructive nature, used in the analysis of such samples. The classicalx-ray imaging methods, radiography and computed tomography (CT), are based on absorption, which works wellfor radiodense structures like bone, but gives limited contrast for textiles and soft tissues, which exhibit highx-ray transmission. Destructive methods, such as classical histology, have historically been used for analysingancient soft tissue but the extent to which it is used today is limited because of the fragility and value of manyancient samples. For detailed, non-destructive analysis of ancient biological samples, we instead propose x-rayphase-contrast CT, which like conventional CT gives volume data but with the possibility of better resolutionthrough the detection of phase shift. Using laboratory x-ray sources, we here demonstrate the capabilities ofphase-contrast tomography of dried biological samples. Virtual histological analysis of a mummified human handfrom ancient Egypt is performed, revealing remains of adipose cells in situ, which would not be possible withclassical histology. For higher resolution, a lab-based nano-CT arrangement based on a nanofocus transmissionx-ray source is presented. With an x-ray emission spot of 300 nm the system shows potential for sub-micronresolution3D imaging. For characterisation of the performance of phase-contrast imaging of dried samples apiece of wood is imaged. Finally, we present the first phase-contrast CT data from our nano-CT system, acquiredof the dried head of a bee.