Hounsfield Unit

1. Definition
   1. XRay attenuation unit used in CT Scan interpretation
   2. Characterizes the relative density of a substance
   3. Each pixel is assigned a value between -1k to 1k
2. Indication
   1. Computed Tomographic Scanning (CT Scan)
3. Substance densities in Hounsfield Units
   1. Air: -1000
   2. Fat: -50
   3. Water: 0
   4. Soft tissue such as muscle: +40
   5. Calculus: +100 to +400
   6. Bone: +1000