1. A method of providing intensity modulated radiation therapy to a target region wherein the tongue and groove effect is minimized, comprising: obtaining a multi-leaf collimator (MLC) sequence from an external leaf-sequencing algorithm; and modifying the MLC sequence to compensate for the tongue and groove effect, wherein modifications are selected such that mechanical limitations of the MLC are not exceeded and at least one of the following is minimized: a non-weighted sum of the tongue and groove effects, a weighted sum of the tongue and groove effects using time-dependent weighting, a weighted sum of the tongue and groove effects using position-dependent weighting, a weighted sum of the tongue and groove effects using time- and position-dependent weighting, the tongue and groove effect distribution variance in spatial coordinates, or the tongue and groove effect distribution variance in temporal coordinates.