TABLE 1.

Contributors of radiation exposure to patients undergoing ERCP

Parameter	Control of Parameter	How it changes radiation exposure
Patient size	Not controllable	Thicker patients require up to 10× as much radiation owing to decreased penetration of the x-ray beam
Difficulty or type of procedure	Not controllable	Some procedures inherently require more fluoroscopy time, which increases radiation exposure
Copper x-ray beam filtration	Property of newer equipment	Automatic addition of copper filtration preferentially attenuates low-energy x-rays and reduces exposure
Collimation and patient positioning without radiation	Property of newer equipment	Done graphically from the last image hold, eliminating the need for additional exposure to accomplish these tasks
Fluoroscopic loop review	Property of newer equipment	Shows the last 10 or more seconds of fluoroscopy without further exposure
Last image hold	Property of newer equipment	Shows just the last image without further exposure
Number of digital spot images taken	Partially controlled by endoscopist	Fewer digital spot images require less radiation
Fluoroscopy time	Partially controlled by endoscopist	Less fluoroscopy time results in less radiation exposure
Pulse mode setting	Partially controlled by endoscopist	Choosing a lower rate will result in less exposure
Image-intensifier magnification mode	Partially controlled by endoscopist	Choosing a lower magnification mode results in lower exposure (exposure in normal mode < exposure in Mag1 < exposure in Mag2)
Dose mode	Partially controlled by endoscopist	Choosing a lower dose setting results in less tube current and less radiation exposure
Collimation	Partially controlled by endoscopist	Using the filtration blades to limit the size of the field reduces the area exposed and improves image contrast
Imaging geometry	Partially controlled by endoscopist	Positioning the patient as close to the image intensifier and as far from the x-ray tube as practical reduces radiation exposure
X-Ray tube potential (kVp)	Partially controlled by endoscopist	Use of an automatic algorithm that uses higher kVp results in more-penetrating x-ray beams and less radiation exposure, although at the expense of less image contrast

Mag1, magnification mode 1; Mag2, magnification mode 2.