Which imaging technique requires a patient screening before use?

The imaging technique that requires patient screening before use is MRI (Magnetic Resonance Imaging). This is because MRI uses strong magnetic fields and radio waves to create detailed images of organs and tissues. Patients must be screened for various factors that could pose risks or interfere with the procedure, such as the presence of metallic implants, pacemakers, certain aneurysm clips, or other ferromagnetic materials inside their bodies. These items can be dangerous due to the magnetic field and can cause injury or complicate the imaging process.

In contrast, X-rays, CT scans, and bone scans do not typically require such extensive screening for metallic objects within the body. While there are some considerations for these techniques, especially regarding patient condition or allergies (for contrast agents in CT scans), they do not have the same strict criteria related to metal and magnetism as MRI does. This emphasizes the unique nature of MRI and the importance of the screening process to ensure patient safety.