What is the procedure of alignment of c arm with ESWL machine (lithotripter).

This procedure may not be applicable with all the models of ESWL equipment manufactured by TMC as some equipment come with an inbuilt imaging system.

This procedure is suitable for Lithotripters that do not have an inbuilt imaging system and the user wants to use a imaging system ( a C-Arm image intensifier ) that is available in most hospitals.

Alignment of the C-arm to the ESWL is achieved using alignment sights on the ESWL and a “cross” to be positioned on the image intensifier. The lower sight is already mounted on the ESWL, it will appear as a “crossbar” on the X-Ray image. The upper sight will appear as a “pointer” on the X-Ray image. The middle sight, pointing to the focal zone, is positioned on the reflector open face and will appear as an “arrow” on the X-Ray image. Place the “cross” at the center of the C-arm image intensifier face. The “cross” now defines the center of the display monitor.                   

The C-arm/ESWL alignment is done using five movable axes on the C-arm: Wig-Wag axis; boom axis; Pitch axis; Roll axis; and the Up-Down axis. The alignment procedure is as follows:

a) Initial position of C-arm axes is as follows:

            Boom                -     Set at Midway of axis.

            Wig-Wag           -     Set at 0 degrees.

            Roll                   -     Set at 0 degrees.

            Pitch                  -     Set at 0 degrees.

            Up-Down            -     Left as is.

b) Turn the C-arm on. 

c) Move Boom and Wig-Wag axes to position the “arrow” tip (focal sight) to the center of the display monitor.

d) Using the display monitor controls, align the vertical axis of the monitor with the orientation of the patient’s spine such that the patient’s head is at the top, and the patient’s left side is on the right side of the screen.

e)  Verify that the arrow is still at the center of the display monitor. If not, perform step c, again.

f)  Lock Boom and Wig-Wag axes in place.

g) Move the Roll and Pitch alternately until the pointer (upper sight), the crossbar (lower sight) and the arrow (focal sight) are all set.

h) Lock Roll and Pitch in place.

i) Move the roll to about a 30 degree angle.

j) Using the C-arm controls adjust the height of the C-arm so that the “cross” on the display is at the tip of the arrow.

k) Move Roll back to 0 degrees and check to make sure the crossbar, the pointer, and the arrow are set as before, and that the “cross” on the display is still where the crossbar and the pointer meet.

l) The C-arm and the ESWL are now aligned.

m) Remove the upper and focal sights from the ESWL and place them aside gently.

You are now ready to go...