You asked for it and here it is: exclusive videos of the CTX Imaging system we showed you yesterday. Here you can see a pig eating in slow motion, starting with the x-ray movie alone and then superimposing the 3D skull.
CTX Imaging is a unique method that uses computed-tomography with high-speed cinefluoroscopic video (1,000fps) and x-rays to create extremely accurate captures of skeletons in very fast motion. We talked with Dr. Elizabeth Brainerd, from the Department of Ecology and Evolutionary Biology at Brown University, who explains this open project after the jump.
[All videos by E.L. Brainerd, K. Metzger and D.B. Baier] Gizmodo: What are we looking at there?
Dr. Brainerd: This is a marker-based CTX of a pig feeding in slow motion, at 1/4 real speed. The pig collects pig chow from the ground and then chews for several cycles before collecting more food. The x-ray movie is shown first, and then the 3D skull and jaw models from CT are superimposed to show the accurate alignment of the bones over time.
Gizmodo: What is the method to achieve this kind of imaging?
Dr. Brainerd: Small metal beads were surgically implanted into the upper and lower jaws and teeth. A 3-D model from CT scanning was made of the skull and jaws. Biplanar, high-speed cinefluoroscopic video of feeding was collected and the X-ray video was used to align the markers in the CT model to produce an accurate (Â±1 mm) reconstruction of bone position over time.
Gizmodo: Amazing, and who is paying for all this cool gear?
Dr. Brainerd: This CTX development project at Brown is funded by the W.M. Keck Foundation and the National Science Foundation.
Gizmodo: How long does it take get the process complete, from the tomography scan to final animation?
Dr. Brainerd: Animal training, surgery to implant the metal spheres into the bones and recovery together take 1-2 weeks. Then we can collect and process the CT scan data in one day and the x-ray movie data in one day.
For one movement sequence it takes about 3-4 hours to extract the 3D coordinates of the metal spheres from the two video views, and then another 3 or so hours to combine the movement coordinates with the 3D model from the CT scan using the animation program Maya. So three days for data collection and processing. We are just getting started with our software development, so we expect that some of these steps will be faster and more automated in the future.
Gizmodo: Are you planning to do this in real time in the future? Is that even possible?
Dr. Brainerd: Real time could, I think, be possible with radiopaque metal spheres surgically implanted in the bones -- so for experimental animals only (not humans).
We currently have no plans to develop real-time CTX imaging because we are creating this technology for scientific research, and we do not see a current research application for real-time imaging. There could be some entertainment value in real time. It sure would be fun to see the bones inside an animal move in real time -- just like having x-ray vision.
(Video at full speed)
Gizmodo: Are there any potential commercial applications?
Dr. Brainerd: There may be future medical applications, particularly in orthopedics, maxillofacial surgery and possibly orthodontics. Seeing bones (and teeth) in action before and after treatment may help plan procedures to match patients' individual needs and to evaluate the efficacy of the treatment. At Brown we have three orthopedic bioengineering faculty on our CTX research team, and research groups at Henry Ford Hospital in Detroit and University of Pittsburgh have made great strides toward developing a marker-less system that can be used for human studies. We are also working toward a markerless CTX system at Brown, but at the moment we have only implemented a system that requires the surgical implantation of small (1 mm or less) metal spheres into the bones.
See abstract of a talk from the HFH and Pitt groups given by Scott Tashman at the 2006 American Society of Biomechanics meeting:
Gizmodo: Are you planning on licensing this technology to other scientific institutions or is it an open project, available for everyone?
Dr. Brainerd: Open project. We are currently working on a web site that will have some software downloads and information on where to buy and how to build the necessary hardware.
Thanks to Dr. Brainerd for her time and all the videos.
(fixed skull, rotating in 3D)
[All videos by E.L. Brainerd, K. Metzger and D.B. Baier]
Bones in Motion: Brown Scientists To Create New 3-D X-ray System [Brown University]
Project page [Brown University]