It would be the PET, Positron Electron (or Emission) Tomography. A CAT scan, which is a Computer Aided Tomography uses a collimator in front of the sodium iodide crystals to get a bearing on the direction of the ray, and it moves the detector around the person to get the information from X-Rays to produce slices or a 3 d representation.
Marshall sol wrote: > This is a PET scan you are talking about? Or is it a CAT scan? MRI? I > lost which test is being examined. > sol > > Marshall Dudley wrote: > > >I believe they use an isotope of tecknesium (sp?). When atoms of this > >isotope decay they produce a positron, which finds an electron and they > >annilate each other. An electron and a positron both contain 511 MeV of rest > >mass energy, so they will produce two gamma rays of 511 MeV that are directed > >almost exactly directly away from each other. Sodium Iodide scintillating > >material surrounds the patient, and then multiple phototubes look at the > >sodium iodide. The configuration is such that the gamma is absorbed by the > >sodium iodide, which produces a flash of light, and the phototubes record the > >light and send the pulse to some pulse analysis hardware and computer. The > >pulse analysis determines exactly where in the sodium iodide the flash > >occured, and with two flashes on opposite sides, the computer figures out a > >straight line between the two, where the original source of the positron will > >be on this line. When another one occurs, if it occurs at the same spot, a > >second line will be computed that will intersect the first line, and that > >will be the spot that the activity is coming from. By analyzing tens of > >thousands of lines, the computer can come up with a pretty good 3 d view of > >where all the activity is. > > > >It is not the positron that causes damage to material, after all the loss of > >an electron is rather non consequential. It is the 511 MeV gamma rays, which > >is an extremely hard x-ray, like cosmic rays. that can cause damage if > >absorbed before they get out of the body. > > > >Marshall > > > > > > > > -- > The Silver List is a moderated forum for discussing Colloidal Silver. > > Instructions for unsubscribing are posted at: http://silverlist.org > > To post, address your message to: [email protected] > Silver List archive: http://escribe.com/health/thesilverlist/index.html > > Address Off-Topic messages to: [email protected] > OT Archive: http://escribe.com/health/silverofftopiclist/index.html > > List maintainer: Mike Devour <[email protected]>
