What is the motion of the fan beam scan arm?

• A. Circular
• B. Linear
• C. Variable
• D. Random

Answer: (B)

The motion of the fan beam scan arm in bone densitometry is primarily linear. This type of motion involves the scan arm moving back and forth in a straight line, allowing for a continuous collection of data along a specific pathway. This linear motion is essential for creating images of the bone density, as it enables the measurement of different sites in a consistent and repeatable manner.

In bone densitometry, the fan beam itself sweeps across the area being scanned, producing images that reflect the density of bones in that area. This linear pathway allows for precise measurements, making it a critical part of acquiring accurate data for assessment of bone health.

Other types of motion, such as circular or random, would not provide the same level of precision and control necessary for bone density measurements. Circular movement might cause overlap and inconsistent readings, while random motion could lead to a lack of reproducibility in results. Thus, the straightforward linear motion of the scan arm is the ideal choice for effective and reliable bone density assessment.