4 ms·

This is actually quite impressive! I wonder how much time it takes to scan one person? If these were made and distributed to enough hospitals adn scan is fast

• car 12y ago
  CT scan time is ~0.2-0.5 seconds for a 160mm slice, so a whole body can probably be scanned fairly quickly. However, CT scanning is only done for the body parts of interest, to keep radiation exposure low. Most fascinating here is the ability to capture a beating heart!
  • ahelwer 12y ago
    It's also computationally intensive to reconstruct all the x-ray images into a 3D model. I worked for a company that wrote software to speed this up with GPGPUs. Standard software packages took on the order of hours for one scan, while parallelism brought it down to 10s of minutes - this was just to transform the x-ray data into voxels. Not sure how long the post-processing to identify & highlight organs would take. It doesn't matter so much for humans, though. The main market for the above-mentioned software product was research labs imaging hundreds of lab rats.
    • marvin 12y ago
      The pretty pictures in the article can be rendered in real time using GPUs. Unless the pictures here use techniques that I haven't heard about, it is done by treating the voxels as a semi-transparent cloud of different-colored materials and using a fragment/pixel shader to simulate rays of light projected through this volume. It's pretty straightforward; the volume data is stored in a 3D texture and each ray of light is simulated using one "pixel" of the fragment shader. This is enhanced by assigning more weight to the voxels that are in a boundary region between tissues of different density (you see this effect in the pictures of lungs, kidneys etc; the organ is transparent but the edges are visible) and applying a shading model to these boundary regions to improve perception of their spatial orientation. Different organs can be pre-selected by marking their constituent voxels, and different models/colors/shading applied to each organ. This process can also sometimes be automated, if you have the luxury of a table that correlates voxel intensity (x-ray absorption value) with tissue type (bone, muscle, air, etc).
      • ajuc 12y ago
        I thought even to get voxels you first have to "solve sudoku"? You have sum of all the voxels "opacity" along rays from many directions and you want to know each voxel opacity.
        • marvin 12y ago
          Yes, my comment only treats the process from the point where you have a complete dataset of voxels to the point where you have a finished rendering. ahelwer didn't treat this part of the process in his comment.
        • ahelwer 12y ago
          It's much, much simpler than that. You just project a ray from the X-ray point source through the center of a voxel onto the detector, interpolate the X-ray energy detected, and add that energy to the sum in that voxel. Repeat for each voxel and each x-Ray taken (CT scans take a bunch of x-Rays going around in a circle), remove some noise, and boom you've voxelled the data. Fundamentally you're just summing the energy that passes through each point in space. It's trivially parallelizeable.
• athenot 12y ago
  Unfortunately, there's a tradeoff: each imaging session exposes the patient to radiation. Too much radiation can be problematic. The article does mention lower exposure but it's not clear whether it's just shorter in time (and more intense) or is the total level of radiation actually lower.
  • wyldfire 12y ago
    The dose is primarily a function of the power delivered to the X-Ray source, the size of the beam and the scan's duration. The big features of this device are coverage (160mm) and rotation speed (mostly dose neutral). If you were imaging 160mm before you had to use multiple sequential scans, so the dose is not significantly different from that scenario. Revolution has similar or superior (meaning less) dose than GE's previous high end scanner. GE's high end scanners tend to offer better dose than the competition.
• fluidcruft 12y ago
  IIRC on this scanner, the actual data collection is very fast (few minutes) but the high-quality image reconstruction needs just under an hour. The images in the link are also heavily manually post-processed which is labor intensive.
  • wyldfire 12y ago
    Hour-long reconstruction times are very abnormal. GE sells a low-dose feature branded "Veo" that has ~30-minute reconstruction times. CT750HD spectral imaging (branded GSI) takes as long as 20-minutes. Revolution imaging takes on the order of minutes (2-3). Indeed the 3d post-processing takes time and probably includes many manual steps/tweaks.
    • fluidcruft 12y ago
      We were told 45-50min was typical for the Veo recons a few months ago, but I wouldn't be surprised if they've improved performance in the interim.
      • wyldfire 12y ago
        Hmm, that's too bad. I could've sworn it had hit the 30-minute mark. There haven't been many refreshes so I don't know that it's been improved since the initial release. Well, IMO, after five or so minutes there's not a huge difference between 30 and 60. But it does depend a bit on how the imaging workflow goes (do you wait for those images before letting the patient leave?, e.g.). But you can get some pretty dramatic image quality or dose improvements from Veo, so maybe it's worth it.
        • deleted 12y ago
          [deleted]