Which diagnostic procedure has the highest radiation exposure listed in the options?

The diagnostic procedure with the highest radiation exposure is a very heavy diagnostic series. This term typically refers to a series of imaging tests, often involving multiple X-rays or fluoroscopy procedures used to thoroughly assess areas of concern within the body. These types of series are designed to gather comprehensive information, which can significantly increase the cumulative dose of radiation received by the patient compared to single diagnostic tests.

In contrast, ordinary chest X-rays generally expose patients to a lower dose of radiation since they typically involve just one imaging session focused on the lungs and heart. A computed tomography (CT) scan, while it does involve more radiation than a standard X-ray due to its detailed imaging capabilities, still often presents a lower overall radiation dose than a very heavy diagnostic series because it is usually performed as a single scan rather than a series. Nuclear medicine scans also have a distinct radiation exposure profile, as they utilize radioactive tracers but typically result in a lower dose of radiation when compared to a comprehensive series of traditional X-rays.

Therefore, the very heavy diagnostic series is recognized for its higher cumulative radiation exposure owing to the nature and number of tests involved in the sequence.