What technique is commonly used to reduce the dose to the patient when positioning a C-Arm?

The technique involving the tube placed under the patient and the image intensifier (II) placed above the patient is effective in reducing the radiation dose to the patient. This positioning allows the radiation to pass through the patient towards the II, rather than scattering back towards the patient, which minimizes exposure to sensitive organs and tissues.

By having the tube positioned beneath the patient, the distance of the primary x-ray beam from the skin is increased, which greatly reduces the entrance dose. Furthermore, placing the II above the patient takes advantage of the geometry of the C-arm, allowing for better visualization of the images while simultaneously ensuring that the majority of the radiation dose is directed away from the patient. This method is utilized frequently in procedures to provide both safety and effective imaging.

Other techniques, such as positioning the tube above the patient with the II below or placing both the tube and II in front of the patient, may not provide the same reduction in patient dose due to increased scatter radiation exposure and closer proximity to sensitive organs.