Study for the CAMRT Radiography Exam. Prepare with flashcards and multiple-choice questions, each question includes hints and explanations. Get ready for your exam!

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What is typically the CT number for fat?

  1. 20

  2. 0

  3. -100

  4. 100

The correct answer is: -100

The CT number for fat typically falls around -100 Hounsfield units. This negative value indicates that fat is less dense than water, which is assigned a CT number of 0 Hounsfield units. The CT scale is calibrated such that the densities of various substances are represented numerically: air has a very low CT number (around -1000), while water is at 0, and various types of soft tissue have CT numbers ranging from slightly positive to just above zero. Fat's unique location on this scale reflects its tissue properties, specifically low density compared to water and soft tissues. The negative value helps radiologists differentiate fat from other types of tissue in CT imaging, which is crucial for accurate diagnosis and treatment planning.