Total marrow irradiation planning, dosimetry and investigation of the effect of organ motion on dose distribution

Total marrow irradiation which is a method treats patients with hematologic malignancies. It is purpose to obtain homogeneous dose distributions in the planning target volume when sparing critical organs such as brain, eyes, oral cavity, lungs, heart, liver, kidneys, rectum and bladder. All the bones in an anthropomorphic rando phantom were contoured. The planning target volume (PTV) was consisted of 3 mm margin for bones. TMI method was performed using intensity modulated radiation therapy technique (IMRT) with the three isocenter technique for an anthropomorphic rando phantom in Varian Eclipse planning system. Thermoluminescence dosimeters put into the rando phantom to determine the effect of organ motion on dose distribution. TMI method was applied for patients with hematologic malignancies after rando phantom study with same technique. The treatment plans were delivered and verified using Matrixx phantom. The prescribe dose was 1200cGy and 150cGy per fraction for all plans. 99% of prescription dose was covered the 99% of target volume for the rando phantom study. Dose values for PTV and organs at risk (OAR) were compared with that of conventional TBI. It was found dose reduction between these two method 28% for lungs and 66% for eyes. When analyzed the effect of organ motion, the average difference between the motion and no motion delivery was found 5%. When applied TMI method for these patients, 95% of prescribed dose was covered 95% of target volume. Mean lungs dose was found 69%. Planar dose distributions of all plans satisfied the 3% and 3 mm gamma criteria with an average pass rate of 97.3%. Good target coverage with significant normal tissue sparing was showed to provide using TMI method in the present study.