Which of the following is NOT a primary type of imaging modality used in radiology?

In the context of imaging modalities used in radiology, the correct choice is blood tests, which are not a primary type of imaging modality. Imaging modalities in radiology are primarily focused on visualizing structures within the body to assist in diagnosis and treatment planning. The main types of imaging modalities include X-ray, ultrasound, and computed tomography (CT).

X-rays use ionizing radiation to produce images of bones and certain tissues, making them a fundamental tool in diagnosing various conditions. Ultrasound employs sound waves to create images, primarily used for examining soft tissues and monitoring pregnancies. Computed tomography combines X-ray technology with computer processing to generate detailed cross-sectional images of the body, providing more comprehensive information than traditional X-rays.

Blood tests, on the other hand, are laboratory analyses conducted on samples of blood to evaluate various health parameters, such as organ function, disease presence, and overall health status. Although blood tests provide critical health information, they do not create images and therefore do not classify as an imaging modality in radiology.