PART 4.4 - PALEORADIOGRAPHY IN RESEARCH
Related technologies
We've come a long way...
I thought it would be wrong not to mention two other technologies used within archaeological research which are based upon X-rays. The following short explanations are provided to spark your interest and acknowledge the existence of computed tomography and X-ray fluorescence.
What is computed tomography?
Computed tomography (CT) can simply be described as radiographs that are taken from multiple angles around the object or specimen and the resultant data is reconstructed using computing power to provide imaging in three planes (coronal, axial and sagittal). I provided a short video in Part 1 to explain the difference between radiography and CT. To supplement this, I have also provided two YouTube videos to explain CT and micro-CT (see below). Whilst conventional CT provides imaging with a resolution measured in millimetres, micro-CT provides resolutions measured in microns (0.001-0.020mm).
A CT scanner is incredibly expensive! It also requires a trained member of staff to operate safely, normally a radiographer. Access to CT is normally outside the scope of archaeological investigators, although there have been numerous examples within the literature of interesting cases (see below). The primary benefit of CT is the demonstration of an object as a volume of data, i.e. the ability to visualise every aspect of the object with overlapping structures as with radiographs. The digital data can be manipulated to demonstrate high or low density structures and three-dimensional reconstructions are also possible.
The imaging of ancient mummies has suffered the same issues of imaging for curiosity, where researchers conducted CT scans of the bodies simply to see what was inside instead of answering a research question. The article by Cox (2015) explores the issue and bemoans the 'Gee wow!' factor associated with the voyeuristic efforts of early examples within academic literature.
Open access examples of CT in archaeology:
My colleagues and I wrote this short case report on the CT scan of Ta Kush, the ancient Egyptian mummy from Maidstone Museum in Kent, United Kingdom. It is open access and can be viewed here.
Another example of CT being used upon an ancient Egyptian mummy, this time to ascertain the cause of death (through violence!).
Open access examples of micro CT in archaeology:
Dambrogio et al (2021) use micro CT to digitally unfold and read unopened letters from Renaissance Europe.
This article shows the use of micro CT to examine dental remains of 17th-19th century Dutch communities to assess for vitamin D deficiency. A good example of bioarchaeology using modern imaging methods.
What is x-ray fluorescence?
X-ray fluorescence (XRF) is another non-destructive method which uses X-rays. Widely used in archaeology, but less so with bony remains, XRF provides the elemental composition of materials according to their interaction with X-rays. In short, the hand-held or desktop machines register the characteristic radiation being emitted from the target material and relate this to the unique element upon the period table. There are no images, but a graph of results informs the investigator the composition of the item.
XRF machines are particularly useful for metal objects to demonstrate purity and perhaps the origin of component materials or place of manufacture (when comparing to items of known provenance). Check out this example of XFR being used to ascertain the authenticity of Victoria Cross (VC) medals. The VC is given to those in the British armed forces for valour in the presence of the enemy. The traditional belief is that each medal is made from the bronze guns captured from the Russians at Sebastopol (1856), but doubt has been questioned in recent times. The article uses XRF as a non-destructive method of analysis for 100 VC medals. Alternatively, you can read this article by Granite and Bauerochse about the use of XFR on a bog body.
Reading Task:
For Part 4 - Paleoradiography in research you are given the opportunity to direct your own reading, according to your own interests.
There are a variety of journal articles on this page, some of which are longer than others and some require institutional access (or payment). You can often gain access through your public library.
You will find a list of the literature below and within the Learning Resources section.
Radiography of skeletons from a London crypt (requires access).
Harris line investigation of medieval Korean skeletons (open access).
Review article on the use of x-rays with metalwork (open access).
Photodensitometry of juvenile archaeological skeletons (open access).
Procedural guide to radiogrammetry for archaeological bones (requires access).
Hunt, Roberts and Kirkpatrick (2018)
Systematic review of evidence for cancer in archaeological literature (requires access).
Review article with case study concerning computed tomography scanning of ancient mummies (open access).
