Tumor motion contributes to the uncertainties. The tumor motions of tumors in different sites have different causes, but for this project the focus is on thoracic, liver, and adrenal gland tumors. The motion of these tumor types is mainly caused by the patient's respiration. So, the tumor motion pattern depends on the respiration pattern of the patient. The motion of lung tumors has been reported to have a peak-to-peak amplitude of up to 24 mm. Currently, the tumor motion is handled by enlarging the margins, such that the tumor is always inside the defined volume. But enlarging the margins also results in an increase of irradiated volume consisting of healthy tissue.