image/svg+xml7 X/1/2019 InterdIscIplInarIa archaeologIca natural scIences In archaeology homepage: http://www.iansa.eu Looking Beyond the Surface: Use of High Resolution X-Ray Computed Tomography on Archaeobotanical Remains Charlene Murphy a , Dorian Q. Fuller a,b* , Chris Stevens a,c , Tom Gregory a , Fabio Silva d,e , Rita Dal Martello a , Jixiang Song f , Andrew J. Bodey g , Christoph Rau g a UCL, Institute of Archaeology, 31–34 Gordon Square, London, WC1H 0PY, United Kingdom b School of Cultural Heritage, Northwest University, Xian, 710069, China c School of Archaeology and Museology, Peking University, 100871, China d Department of Archaeology, Anthropology and Forensic Science, Bournemouth University, Fern Barrow, Poole, Dorset, BH12 5BB, United Kingdom e Faculty of Humanities and Performing Arts, University of Wales Trinity Saint David, Lampeter Campus, Ceredigion, SA48 7ED, United Kingdom f Department of Archaeology, Center for Archaeological Science, Sichuan University, Chengdu, China g Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, OX11 0DE, United Kingdom 1. Introduction High Resolution X-Ray Computed Tomography (HRXCT) imaging ofers a powerful 3-dimensional, non-destructive and non-invasive diagnostic tool to image the external and internal properties of a range of specimens of interest (Friis et al. , 2014). HRXCT ofers new possibilities in terms of the research questions which may be asked of fragile and valuable archaeological and specifcally archaeobotanical material. This paper will discuss the methods and results of the successful use of HRXCT to image preserved archaeobotanical specimens of horsegram ( Macrotyloma uniforum ) from diferent time periods ranging from the Neolithic (4,000 BP) to modern specimens (present day) from South Asia, and additional taxa including lentil ( Lens culinaris ), goosefoot ( Chenopodium sp.), and soybean ( Glycine max ).HRXCT has grown in popularity recently as it has become more user friendly – with a broad range of disciplines employing this imaging technique, including: material sciences (Guo et al. , 2017), art conservation (Cotte, 2016), conservation (Wilson et al. , 2017), heritage studies (Bertrand et al. , 2012), paleobotany (DeVore, Kenrick, Pigg, 2006; Friis et al. , 2007; 2014; Scott et al. , 2009), plant sciences (McElrone et al. , 2013; Staedler et al. , 2013), archaeological artefacts (Mocella et al. , 2015; Bukreeva et al. , 2016), archaeobotanical material (Murphy and Fuller, 2017; Zong et al. , 2017), soil micromorphology (O´Donnell et al. , 2007) and sedimentology (Appoloni et al. , 2007). HRXCT is a very efective method for a large range of disparate disciplines as it encompasses a wide variety of Volume X ● Issue 1/2019 ● Pages 7–18 *Corresponding author. E-mail: d.fuller@ucl.ac.uk ArTICLE INFO Article history: Received: 2 nd May 2018 Accepted: 9 th May 2019 DOI: http://dx.doi.org/ 10.24916/iansa.2019.1.1 Key words: High-Resolution X-Ray Computed Tomography (HRXCT)Synchrotronmorphometricsimagingarchaeobotany ABSTrACT High Resolution X-Ray Computed Tomography (HRXCT) ofers a powerful 3-dimensional, non- destructive and non-invasive diagnostic tool for imaging the external and internal structures of a range of specimens of interest including archaeobotanical remains. HRXCT ofers new possibilities in terms of the research questions which may be asked of fragile and valuable archaeological and specifcally archaeobotanical material. This technology, although currently somewhat limited in terms of time and access to beamtimes at National Synchrotrons, requires simple, non-destructive preparation of samples and produces exciting results. Based upon two rounds of successful work, we believe that this new methodology has wider implications and utility for advancing the feld of imaging, and investigating aspects of plant domestication such as internal anatomical changes.
image/svg+xmlIANSA 2019 ● X/1 ● 7–18 Charlene Murphy, Dorian Q. Fuller, Chris Stevens, Tom Gregory, Fabio Silva, Rita Dal Martello, Jixiang Song, Andrew J. Bodey, Christoph Rau: Looking Beyond the Surface: Use of High Resolution X-Ray Computed Tomography on Archaeobotanical Remains 8 advanced microscopy and imaging techniques, which can be adapted to the heterogeneous and complex structures of the materials imaged (Bertrand et al. , 2012; Cnudde and Boone, 2013). Resolutions can be a little better than a micron with microtomography, and extend to nanometers with nanotomographic methods. For our research purposes, we looked at both charred and modern seeds. We started with a 15 KeV monochromatic beam, but progressed to using a fltered pink (polychromatic) beam for an improved high signal to noise ratio, which provided consistent and excellent image contrast for most plant applications (McElrone et al. , 2013; Murphy and Fuller, 2017). 1.1 Synchrotron technology HRXCT with a synchrotron employs the same principles as current medical CAT-scanning to generate three-dimensional images from two dimensional projections taken at diferent orientations of the specimen. HRXCT uses energies that are high enough to penetrate and study the internal structures of the specimens (Bird et al. , 2008; Pantos, 2005, p.199). Synchrotron radiation is made up of extremely bright light. This type of radiation is naturally emitted by cosmic sources, but it can also be generated at synchrotron facilities such as Diamond Light Source in the UK (Figure 1) (Bertrand et al. , 2012). Synchrotron radiation is produced when electrons are sped up to extremely high velocities by a linear accelerator and sent into orbit within a storage ring. Magnets, placed at various locations throughout the synchrotron storage ring, regularly bend the path of the accelerated particles as they circulate, generating synchrotron radiation (Winick, 1994; Greene, 2016) – Figure 2. The synchrotron radiation is produced with a high degree of parallelism, ranging