AUTOMATIC C-ARM REPOSITIONING USING A TWO-BAR LINK SYSTEM FOR REDUCING RADIATION EXPOSURE

A C-arm fluoroscopy is a useful instrument for finding out the position of a needle in a minimally invasive surgery, but its use means that the surgeon and patient are exposed to radiation while the surgeon places the C-arm into the previous position and orientation as well as he/she regularly uses it to take X-ray images. In this paper, a two-bar link system and moving mechanism added on a C-arm are proposed to reduce the dose of the exposure. The two-bar link system consists of two bar links and three absolute encoders. It measures the relative position and angle between the C-arm and the surgical table in real time and stores the measurements in the system. The moving platform of C-arm is proposed to have two switchable casters for both passive freewheeling and active motor driving. Passive freewheeling allows the C-arm to be freely moved by human force and active motor driving returns the C-arm to its original position automatically. A simple experiment is performed to verify the feasibility of C-arm repositioning using a two-bar link system.