This is a new technique of producing high energy X-rays for radiation therapy at a patients level. The dose delivery system uses a linear accelerator with no flattening filter. The technique improves patient radiation therapy by reducing radiation scattered to surrounding normal tissue and reducing electron contamination. It increases dose rate to shorten treatment time. The flattening filter reduces the efficiency of the beam by reducing the fluence and increasing scattered radiation. This technique involves removal of the flattening filter. It uses inverse planning to shape the dose distribution.