The Application Study Of Spectral CT Examination In The Ancient Archaeology

Objective:The purpose of this study is to try to apply the CT examination in ancient archaeology, first to study the feasibility and application of spectral CT scanning in anthropology evaluation of human bones with copper arrowhead in Jing Gou Zi tomb and copper arrowhead itself,then to research CT and multiple reconstruction techniques in the detection and diagnosis of diseases of ancient people. Materials and methods:A right hip(03LJM46B) and two lumbar vertebrae(03LJM47B) with copper arrowhead and an ancient human skull with suspected lesions(03LJM55B) were the research objects in this study. These bones were unearthed at Jing Gou Zi tomb in Linxi County, north of the city of Chifeng in Inner Mongolia Autonomous Region site. Radiocarbon dating shows that the age was 2485+45BP, roughly in the late Spring and Autumn period to the Warring States period.All human bones were performed spectral CT scanning, spectrum analysis software and MARs technology used to remove metal artifacts caused by copper arrowhead to obtain clear CT images. Gemstone spectral imaging(GSI) was applied to M47 B second lumbar vertebrae and one lumbar sample after lumbar internal fixation. The effect in removing metallic artifacts on GSI with Mono(monochromatic) or Mono+MARs(Metal Artifact Reduction System) by 120 ke V was explored. Then the efficiency of GSI in removing metallic artifacts caused by bronze Zu arrowheads was obtained. Quantitative image analyses and qualitative image analyses were carried out based on Mono images and Mono+MARs images of M47 B second lumbar vertebrae and the lumbar sample after lumbar internal fixation. Quantitative image analyses included: CT Housefield unit of metallic artifacts resulted from bronze Zu arrowheads and nail-stick system of internal fixation, and the cancellous bone. Qualitative image analyses included: the scale of metallic artifacts caused by bronze Zu arrowheads and nail-stick system of internal fixation. The efficiency of reducing metallic artifacts caused by bronze Zu arrowheads with GSI were analyzed through quantitative and qualitative image analyses.In the study of anthropology, a series of data of the right hip and lumbar vertebrae were obtained using bone measurement instruments. At the same time, the CT image data of them were imported into the postprocessing software, Mimics, to obtain reconstruction images and the parameters in 3D model, and the statistical analysis of data aimed to judge the reliability of measurement using CT scanning. Using these parameters, the age and height of the owner of the right hip and lumbar vertebrae age were calculated. Finally, the injury and the pathological changes of the right hip and lumbar vertebrae caused by copper arrowhead were analyzed from CT images.Study on the shape of copper arrowheads, vernier caliper was used to measure part parameters of the copper arrowheads exposed outer of bone. At the same time, the CT image data were imported into Mimics software for 3D reconstruction, the copper arrowheads were isolated from human bone virtually and basic parameters of copper arrowheads were measured in 3D reconstruction model. Finally, the bounding box and the center of the copper arrowhead were constructed in Mimics software, the relationship of copper arrowheads and other copper arrowheads over the same period was analyzed by compared the parameters of them.The CT images of the ancient skull with lesion was obtained and CT scan data were reconstructed using advanced volumeshare 4.0(ADW4.0) imaging software on a CT workstation, including volume rendering(VR), multiplanar reconstruction(MPR), maximum intensity projection(MIP), tissue transition projection(TTP) and CT virtual endoscopy(CTVE). Paraffin-embedded specimens stained with HE were performed. Result:1. In the condition of 120 ke V, CT Housefield unit of metallic artifacts induced by the bronze Zu arrowhead on Mono+MARs images is lower than that on Mono images(-951.3±20.9 vs.-400.5±52.5, p < 0.001), and the noise of metallic artifacts induced by the bronze Zu arrowhead on Mono+MARs images is lower than that on Mono images(20.6±9.37 vs. 64.6±13.98, p < 0.001). The scale of metallic artifacts caused by this bronze Zu arrowhead on Mono+MARs images is superior to that on Mono images(2.26±0.72 vs. 4.44±0.82, p < 0.001). The effect of reducing the metallic artifacts caused by this bronze Zu arrowhead is favorable on Mono+MARs images. The boundaries of bronze Zu arrowhead and second lumbar vertebrae are clear; it’s beneficial for the extraction of boundary and 3D reconstruction.2. There was no significant difference between the physical anthropology data of the right hip and lumbar vertebrae using instrument and 3D reconstruction images and the 3D images were not restricted by space and can get more data. Also the individual age and height of the right hip and lumbar vertebrae were calculated. CT images also showed the bone density around the copper arrowheads decreased and the CT value reflected the pathological change of osteoporosis in the corresponding region.3. Study on the shape of copper arrowheads showed that there was obvious difference between the distance of each wing of two copper arrowheads. The two arrowheads maybe come from different places. But there was no significant difference in distance between surface contour point to the centre of the arrowhead and some kind of relation between the two arrowheads existed.4. The CT images of the skull indicated a reduction in bone density and relatively homogeneous lesions. More features were revealed using CT reconstruction techniques. Lesions seen in low-magnification images using a 3D deep-field microscope had an irregular honeycomb-like structure. Paraffinembedded specimens stained with HE showed trabeculae with tortuous irregular arrangements varying in shape and width. Those features have been described as having fibrous dysplasia. Conclusion1. It is feasible that CT examination can be used in the ancient human archaeology.2. Physical anthropology data of ancient human bones can be obtained using CT imaging without damage to the specimen and more data can be obtained than using traditional measuring tools. Data of CT imaging is benefit to realize digitization of ancient bones.3. Spectral CT imaging and postprocessing can eliminate the metal artifacts of the copper arrowheads and obtain complete information of the arrowheads.4. CT examination and reconstruction techniques applying in ancient human specimen combined with histological can make a preliminary diagnosis of ancient human diseases.