What anatomical feature must be aligned with the scanning device for accurate bone density measurements?

• A. The spine
• B. The knees
• C. The pelvis
• D. The shoulders

Answer: (C)

For accurate bone density measurements, it is essential that the pelvis is properly aligned with the scanning device. The pelvis is a critical anatomical site for assessing bone mineral density because it is a weight-bearing area where osteoporotic fractures commonly occur. Misalignment can lead to inaccurate results due to improper positioning, which can affect the measurement of the bone density values obtained and ultimately influence patient diagnosis and management.

In the context of dual-energy X-ray absorptiometry (DXA), which is typically used for bone densitometry, proper alignment ensures that the region of interest—the pelvis—is captured entirely within the scan field and that the measurements reflect true bone density rather than artifacts caused by mispositioning. This is why ensuring the pelvis is aligned is paramount for reliable and consistent results.