High School SMILE Meeting
1997-98 -- 05-06 Academic Years
Medical Physics

*** Medical Physics ***

07 November 2000 Walter McDonald (CPS Sub and X-Ray Technician)
set up a transparent vertical sheet of plastic on the table, with a fluorescent lamp as illumination from behind, and he then displayed some large X-ray images of the spine, one after another, pointing out how he had enhanced some of them for detail using computer processing. According to Walter, the images are not produced by using a chemical liquid developer of a film emulsion, but rather through a process which reads the x-ray exposure on a plate and stores the result directly into computer memory. Interesting, Walter!

10 December 2002: Walter McDonald (CPS Substitute and X-ray Technician)  X-ray Images
showed X-ray images of live organisms that are created by making two exposures at lower and higher energy X-rays, and digitally combined to show separate images for bone and soft tissues.  In general, it is possible to lower the X-ray exposure received by patients in diagnostics, using this technique. These images, obtained through Dual Energy Subtraction Radiography,  [http://www.itnonline.net/ and http://www.gemedicalsystems.com/rad/xr/radio/products/de_perspectives.html] are quite useful in obtaining enhanced images of the skeletal system, as well as images in which the skeletal system is largely eliminated.  He mentioned that these images can also be used to determine bone mineral content, to look for signs of calcium depletion, for example as an indication of osteoporosis. Porter mentioned that one can target the location of a specific element, such as iron in the blood or Calcium in the bones, by using X-rays of energies just below and just above an ionization energy of inner electrons  [ about 13.6 ´ Z2 electron Volts for an atom of Atomic Number Z], to obtain images for the distribution of the element in question. With millisecond timing of X-ray pulses, one could make images of the blood distribution in and around the heart, between beats. For further discussion see the website http://www.radiologyinfo.org/content/mr-angiography.htm. Thanks for calling our attention to these exciting new diagnostic techniques, Walter!

25 February 2003: Walter McDonald passed around an article by Jim Ritter [Health Reporter] in the Metro Section of the Chicago Tribune of Friday 13 December 2002, which described the use of magnetic fields to guide the course of a catheter with a magnetic tip, which is used in connection surgery on the brain.  The catheter is fed through the femoral artery close to the surface in the groin area, and then magnetically guided through the large blood vessels to the region of interest.  Its course is tracked with X-rays that are taken every 3 seconds during surgery.  This catheter can reach 85-95 % of the brain , in contrast to conventional catheters that can only reach 60 % of the brain.  The treatment shows promise in treating blood clots, strokes, aneurisms, brain tumors, epilepsy, Parkinson's disease, and other brain disorders, with surgery that avoids the need for drilling holes in the skull.  It also shows promise in opening clogged arteries in the heart.