What are the two types of collimators commonly used in DXA?

• A. Fan and pinhole
• B. Circle and square
• C. Laser and optical
• D. Linear and circular

Answer: (A)

The primary types of collimators used in Dual-energy X-ray Absorptiometry (DXA) systems are indeed the fan and pinhole types.

Fan collimators are designed to shape the X-ray beam into a fan-like geometry, allowing for the scanning of larger areas at once. This is especially useful in DXA examinations, where a comprehensive assessment of bone density over a specified region, such as the lumbar spine or hip, is necessary. The fan shape increases the efficiency of the scan and enhances image quality by minimizing scatter radiation.

Pinhole collimators, on the other hand, create a narrow beam that is directed through a small opening, which helps in improving spatial resolution. This type of collimation is beneficial for detailed imaging in specific areas but is less common for full scans due to its limited field of view.

Together, these collimation methods optimize the performance of DXA systems by facilitating accurate bone density measurements while minimizing interference from surrounding tissues.