Which of the following describes the function of a phantom used for daily QC?

• A. To measure patient density
• B. To assess operator skills
• C. To ensure machine accuracy over time
• D. To calibrate new sensors

Answer: (C)

The function of a phantom used for daily quality control (QC) is crucial in ensuring that a bone densitometry machine remains accurate over time. A phantom is a standard reference object that mimics human bone density and composition, allowing operators to perform consistent and reproducible testing.

By using a phantom, operators can evaluate the precision of measurements taken by the machine. The phantom provides a baseline against which daily measurements can be compared. If the machine's readings deviate from the expected values obtained with the phantom, it indicates a potential issue with the machine's calibration or function that needs to be addressed.

This practice of using a phantom provides ongoing assurance that the equipment operates within acceptable limits, thus ensuring the reliability of the bone density measurements for patient assessment, which is critical in diagnosing and managing conditions like osteoporosis.

Other options, while related to bone densitometry, do not accurately reflect the primary function of daily QC phantoms. For example, measuring patient density involves evaluating individual patient results rather than the machine's operational accuracy, assessing operator skills is an evaluation of proficiency unrelated to the phantom's function, and calibrating new sensors pertains to an initial setup rather than ongoing accuracy checks.