Christine, after the bantering of some people...
As someone wrote: Is the radiation according to a L4_L5 problem? Or below? If not rethink, What about triggerpoints in the gluteal area and lumbar area? Some might trigger pain in the legs. And not always according to Travell.
Is it possible having an orthosympathetic involvement, check mobility and pain from T8 to L1 (T11-L1 should cause pain on overpressure and deep palpation paravertebral) What about muscle length/ strength?
Best effect by traction, specific mobilisation of effected vertebraes. Mobilization ala Butler. Muscle strengthening in semi flexion, e.g. push lower part of back down onto the floor.
Best of luck.