Results: Averaged over ten patient simulations, targeting errors along the x, y, and z coordinates (patient's left-to-right, posterior-to-anterior, and head-to-foot) were, respectively, -0.060±0.363, -0.350±0.253, and 0.348±0.204 mm when MRI was used for treatment planning. Planning according to CT exhibited generally smaller errors, namely, 0.109±0.167, -0.191±0.144, and 0.211 ±0.094 mm. The largest errors along individual axes in MRI- and CT-planned treatments were, respectively, -0.761 mm in the y-direction and 0.428 mm in the x-direction, well within safe limits.
