detectors application_number US 44945799 A description referring to fig1 a main support 10 can be secured to the floor of an x ray room or to a movable platform not shown and has a track 12 on which a lower slide 14 rides for movement along an x axis slide 14 supports the proximal or near end of a generally horizontal lower arm 16 through a bearing at 18 allowing rotation of arm 16 about an upwardly extending axis e g a z axis the distal or far end of lower arm 16 in turn supports an upwardly extending e g vertical column 20 mounted for rotation about an upwardly extending e g vertical axis though a bearing at 17 column 20 has a slot 20 a along its length an upper slide 22 engages slot 20 a to ride along the length of column 20 and is supported by a cable or chain system 24 that reverse direction over pulleys 26 at the top and bottom of column 20 only the top pulley is illustrated and connect to counterweights 28 riding inside column 20 upper slide 22 in turn supports an upper arm 30 through a bearing arrangement at 32 allowing rotation of upper arm 30 about a lateral e g horizontal axis extending along the length of upper arm 30 preferably the bearing arrangement is situated along the center of.