What consequence does decreasing the field size from 16" to 4.5" have in fluoroscopy?

Decreasing the field size from 16 inches to 4.5 inches in fluoroscopy primarily leads to an increased radiation dose to the patient. When the field size is reduced, a greater amount of the available radiation is concentrated on a smaller area of the patient's body. This increased intensity results in a higher dose of radiation being delivered to that specific area, which is particularly significant in fluoroscopic procedures where radiation is already being used continuously.

This focus of radiation on a smaller area can increase the exposure to the tissues being imaged. The body may absorb more radiation per unit area, leading to a potential increase in dose without necessarily improving the quality of the image. It's important to carefully manage field sizes in fluoroscopy to minimize the radiation dose while still obtaining clear and useful diagnostic images. Thus, while other factors such as image quality can be affected by field size, the primary consequence of decreasing the field size is the increased radiation dose.