In situ position-resolved x-ray diffraction of an intact Roman-era Egyptian mummy guided by computed tomography

S. R. Stock; M. K. Stock; J. D. Almer

doi:10.1117/12.2530925

17 September 2019 In situ position-resolved x-ray diffraction of an intact Roman-era Egyptian mummy guided by computed tomography

S. R. Stock, M. K. Stock, J. D. Almer

Author Affiliations +

Proceedings Volume 11113, Developments in X-Ray Tomography XII; 1111312 (2019) https://doi.org/10.1117/12.2530925
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

Contrast in Computed Tomography (CT) most often relies on absorption differences, and reconstructions give absorptivity of each volume element (voxel) but not the material’s identity. This paper describes the first use of in situ position-resolved x-ray diffraction to identify different contents (see below) within an intact mummy. Hawara Portrait Mummy No. 4 (HPM4) was first imaged with a clinical CT scanner, and this 3D “roadmap” guided diffraction mapping at beamline 1-ID of the Advanced Photon Source. Only 24 hrs were available, and the CT data allowed mapping of only the volumes of interest. The long beam path through the mummy was a major complication solved by collecting each diffraction pattern at two detector-mummy separations. Accuracy in diffracting volume positions was 1-2 mm, and precision sufficed for diffraction identification of the materials. Diffraction patterns were collected from the mineralized tissues within the five year old child’s mummy (HPM4), specifically the skull, cervical vertebrae, femora and teeth. Patterns from the femorum lateral and medial sides (and the skull’s left and right sides) could be analyzed separately. Lattice parameters and crystallite sizes of the bones’ mineral phase were comparable with those from modern bone. Within the wrappings, wires were located by diffraction and identified as a modern dual phase steel, probably introduced during earlier conservation. Highly absorbing, millimeter-sized inclusions were identified as calcite. The position of these and other features were found at the positions indicated by the CT scans, and the limitations of the diffraction approach compared to absorption CT are discussed.

Conference Presentation

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S. R. Stock, M. K. Stock, and J. D. Almer "In situ position-resolved x-ray diffraction of an intact Roman-era Egyptian mummy guided by computed tomography", Proc. SPIE 11113, Developments in X-Ray Tomography XII, 1111312 (17 September 2019); https://doi.org/10.1117/12.2530925

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