I am in the need of scanning some fossils for analyzing their inner structure. Unfortunately I don't have access to a proper CT or micro-CT of industrial use that suits nicely fossils and neither the country in which these specimens are housed. Despite this I can manage to get access to some nice medical CT scans as a plan B.
I was wondering which are the drawbacks or disadvantages of working with these medical CT, as I have never used them in this way before. I understand that resolution or maybe the potency of it might be different, but besides that I don't have any other guess. I'm interested in managing the data of these scans, as it might be the only chance I have to scan these specimens.
Any help would be really appreciated.
Thanks in advance.
Hi, in my experience, medical CT scan machines may be good. I got very good scans of Pliocene dolphins from a medical CT scan machine in the past. However, you need to be careful about the fine tuning of the beams because not expert technicians could use too much or too few energy resulting in loss of contrast and details of your CT scan. I guess that this may be a common problem for both medical and industrial CT scans. Good luck!
You need to first define what resolution and field of view (FOV) you are looking for. Medical CTs are optimized for relatively low dose and seldom are we looking for the "inner structure" of bones. Typically a reconstructed image size is 512 x 512 or on that scale across the entire field of view. So, if your FOV is large, you can imagine your voxels will be pretty large. Most can only generate about 0.5 to 0.6 mm slice thickness, which will limit you in that dimension. I'm pretty sure there are scanning services out there, and possibly you can find a collaborator with access to a micro-CT to provide you the appropriate resolution.
In a word, don't. I used a medical CT-scanner to try and get CT-scan data for the fossils I did for my master's thesis as well as some other undescribed material. What I found out is the thing about medical CT-scanners is they have a pre-set limit on how high the intensity of the radiation can go in order to avoid an accident accidentally killing the patient by setting the radiation too high. It's pretty well establishing in the CT community exactly how strong the process has to be to distinguish flesh from bone and other tissue, so the limits on the scanner are pretty well defined.
What this means, however, is that if you are trying to distinguish fossil bone from rock it won't work, as in most cases the CT machine won't even have enough power to penetrate the material because it's set to go through squishy flesh and unfossilized bone. On the material I worked with, I got a featureless blob on the inside with no details whatsoever. A medical CT-scanner should work if you are scanning unfossilized zoological specimens, but if you are scanning fossil specimens with matrix you are out of luck. You need an industrial CT-scanner, because they are constructed to use much higher doses of radiation because they normally don't have to worry about killing their scanning subject.
The Human Evolution Laboratory (LEH, Laboratorio de Evolución Humana, ; www.ubu.es/leh) of the Department of Historical Sciences and Geography of the University of Burgos (Spain) have an interesting Micro-CT scanners. They have experience in vertebrates and invertebrates, and the prices are moderate. Url:
https://www.ubu.es/laboratorio-de-evolucion-humana-leh
Luck
Thanks for the wide array of answers. Unfortunately I wont have any access to any other CT but these medical ones that I can manage. The country where these fossils are located does not have infrastructure or institutions with the right equipment. We have access to a nice micro-CT at my current lab, but exporting some of the specimens would we logistically impossible (either too large or fragile). I guess this will be a matter of exploring the fine-tunning of the beams and trying if it works.
Dear Aldo Benites-Palomina
I am a doctoral student working on macrofossils (corals). In macrofossils, we prepare a thin section to examine and see the internal structure, and if the thin section is not responsive, we prepare a peel. Since you are working on vertebrates, medical CT scans are the best option for viewing the internal structure and preserving fossils. Have you ever taken a picture? My suggestion is to try the MRI once if you can. With respect
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