Keeping the I-I as close to patient’s surface as possible significantly reduces patient and operator exposures (Figure \). The I-I will intercept the primary beam earlier and allow less scatter to operator and staff. In addition, The Automatic Brightness Control (ABC) system would not need to compensate for the increased X-ray tube to I-I distance caused by the air gap. The presence of an air gap will always increase patient/operator radiation exposure and decrease image quality.
Figure: Benefit of Reducing the Air Gap (I-I Close to Patient)
Courtesy of Sorenson, 2000.
Care should be taken whenever the image view angle is changed during the procedure (e.g, changing from an ANT to a steep LAO). The I-I is often moved away from the patient while changing X-ray tube position. Large air gaps can result if the table or I-I height remains unadjusted.
