What does the CT number, or Hounsfield unit, indicate?

The CT number, commonly referred to as the Hounsfield unit, is a specific measurement that indicates the density of a tissue relative to water. This unit of measurement is crucial for tissue characterization because it allows radiologists and medical professionals to differentiate between various types of tissues based on their density. Water is assigned a value of zero Hounsfield units, while air, fat, muscle, and dense tissues like bone are given negative, low positive, and high positive values respectively. This standardized scale provides valuable information for diagnosing conditions and understanding the composition of structures within the scanned area. This understanding enhances the ability to identify abnormal growths, fluid collections, and other variations in tissue density, facilitating improved patient management and treatment planning.