A patient bed includes a base, a patient support, and an elevation mechanism for raising or lowering the patient support relative to the base. The elevation mechanism comprises a first pair of arms and a second pair of arms, with both the pairs of arms mounted relative to the patient support and the base. The first pair of arms and the second pair of arms have pivot connections at the patient support, with the pivot connections of at least one pair of the pair of arms moving in a sinusoidal path when the patient support is raised or lowered with respect to the base.