5. Traditional X-rays The 3 main parts of any x-ray tube are the anode, cathode & the tube When a filament is heated, much like a light bulb, electrons are ejected from the surface of the cathode

6. Traditional X-rays A large electrical potential, commonly called voltage, between the cathode and the anode force electrons emitted from the filament to accelerate towards the anode The beam is focused these electrons onto a small area on the tungsten anode

7. Traditional X-rays The electrons hitting the tungsten anode produce radiation at an efficiency of only 1% The other 99% is dissipated into heat at the surface of the target Copper is used to conduct this heat away Glass used in x-ray machines is high in lead content to prevent unwanted radiation from being emitted from the housing

10. Image Production Attenuation  Density =  Attenuation =  ”Blackness”

11. Physical Density vs Radiographic Density Paradoxical relationships Radiolucent vs Radiopaque

12. Densities Gas (black) Fat (Gray-black) Water (Gray) Bone (White)

13. Image Quality Thickness Motion Scatter Magnification Distortion

26. Helical CT Scanners takes advantage of 3rd generation computed tomography and utilize “slip-ring” technology the patient is transported without pause as the tube and detector rotate continuously around the patient

27. Helical CT Scanners This produces a corkscrew-like path through which the data is acquired The pitch of the scan, or helix, is defined by how far the patient is “translated” during one rotation of the tube The time it takes for a single rotation of the tube and detector is approximately 1 second The process is much, much faster than traditional CT scanners

29. MRI Principles TR (repetition time):refers to the time in milliseconds between the 90 deg RF pulses; Echo time (TE):is time between the RF pulse and the recording of signal;time in milliseconds between application of 90 degrees RF pulse and recording the signal (echo) produced by the sample.

30. MRI Prinicples The repetition time (TR) is the time between the RF pulses and the echo time (TE) is the time between the RF pulse and the recording of the signal. T1-weighted images (short TR/short TE) provide the best anatomic detail, but T2-weighted images (longTR/long TE) are often needed to demonstrate pathology.

31. T1 Images Provide the best anatomical detail Most useful for lesions involving marrow and SubQ fat Cortical bone, ligaments and tendons also have long T1 values

32. T2 Images Neoplasms, fluids and inflammation Used to distinguish between normal and abnormal soft tissues

54. Bennett’s Fracture

61. Anterior and Posterior Columns

62. Anterior Column

63. Posterior Column