Radiologic Technologist Practice Exam

Which imaging modality provides the highest dose of radiation for an average patient?

1. X-ray

2. CT scan

3. Ultrasound

4. MRI

The correct answer is: CT scan

The choice of CT scan as the imaging modality that provides the highest dose of radiation for an average patient is accurate because computed tomography (CT) involves the use of ionizing radiation to produce detailed cross-sectional images of the body. Unlike traditional X-rays, which give a limited two-dimensional view and typically involve lower doses of radiation, CT scans create multiple images and utilize a higher level of radiation to enhance the clarity and detail of the images produced. For instance, a single CT scan of the abdomen can expose a patient to a radiation dose equivalent to several hundred chest X-rays, depending on the specific scan protocol and the area being imaged. This higher radiation dose is necessary to achieve the diagnostic quality that CT imaging offers but does increase the patient's exposure compared to other imaging modalities. Ultrasound and MRI, on the other hand, do not use ionizing radiation at all. Ultrasound employs sound waves to create images, while MRI uses strong magnetic fields and radio waves. Because they do not involve radiation exposure, they are generally considered safer alternatives, especially for repeated imaging or for populations more vulnerable to radiation effects, such as children or pregnant women.