| 摘要 |
<p>A patient support system for irradiation therapy or treatment simulation comprises a main arm (1) on a sub-floor mounted pivot (10) about a first vertical axis (17), which supports a further arm (49) rotatable about a second vertical axis (16). At the other end of the arm (49) a vertical pillar (4), pivotable about a third vertical axis (15), supports a vertically displaceable carriage (3) on which a patient support table top (2) is directly mounted. A control system is described which enables x, y coordinate command values to control respective drives associated with the three vertical axes to position a patient quickly and accurately relative to the treatment isocentre. This takes the form of a cartesian error nulling arrangement in which the actual coordinates Xa(act), Ya(act) are computed (143) from angular measurements phi1, phi2 (116A,104A) about axes (17) and (16), cartesian error signals EX, EY are formed by subtraction (146,147), and angular error signals Ephi1, Ephi2 are derived therefrom to actuate the respective motor drives (131, 132), phi3 being derived from phi1 and phi2 to maintain a steady direction for the table top (2). The system requires only a shallow well while providing a large range of vertical lift. Furthermore, no sub-table x-y carriage is required increasing patient accessability.</p> |
