Which scan speed/mode should be used for a body part with a thickness greater than 25 cm?

• A. Thin Mode (Lunar)
• B. Standard Mode (Lunar)
• C. Thick Mode (Lunar)
• D. Fast Array (Hologic)

Answer: (C)

Using Thick Mode for a body part with a thickness greater than 25 cm is appropriate because this mode is specifically designed to accommodate and optimally image denser and thicker areas of the body. When the body part exceeds 25 cm in thickness, using a mode that is engineered for thicker areas ensures that the resulting scan captures sufficient detail and accuracy in bone density measurements.

Thick Mode can take into account the greater attenuation of the X-rays due to the increased density encountered in thicker anatomical regions. This results in improved image quality and more reliable data on bone mineral density, which is critical for diagnosing conditions such as osteoporosis.

In contrast, other modes like Thin Mode or Standard Mode may not penetrate adequately through thicker tissues, potentially leading to inaccurate measurements or missed diagnoses. Fast Array, while efficient, is typically used for speed and may sacrifice some level of detail that is necessary for thorough assessment in thicker body areas.