During which imaging procedure is gel often applied to the skin?

The application of gel to the skin is a standard practice during ultrasound imaging procedures. This gel serves several important purposes: it acts as a conductive medium that helps transmit sound waves between the ultrasound transducer and the skin, allowing for clearer images of the internal structures being examined. Additionally, it reduces air pockets that could interfere with the sound waves, ensuring that the ultrasound waves are effectively transmitted into the body.

In contrast, other imaging modalities such as X-rays, CT scans, and MRI do not typically require gel on the skin. X-rays usually involve direct exposure to the imaging plate or film without the need for a gel medium. CT scans involve the use of advanced imaging technology and typically do not necessitate a direct contact gel application, as they utilize X-ray equipment. MRIs use magnetic fields and radio waves to create images and generally do not require gel; however, some specific MRI techniques may employ a different approach for patient comfort or specific imaging purposes, but this is not standard. Thus, gel application is closely associated with ultrasound procedures, making it the correct choice for this question.