ABSTRACT
Objective To introduce the therapeutic procedures of helical tomotherapy based total marrow irradiation(HT-TMI), and validate the feasibility of TMI. Methods At 1 week before bone marrow transplantation,12 patients received TMI conditioning regimen at a prescriptive dose of 12 Gy in 3 times,once daily. Patient immobilization, CT simulation, target delineation, plan design and dosimetric verification were implemented in sequence according to the TMI procedures. The dosimetric paramaters of the target and normal tissues were analysed. The correlation between the dose verification and image-guided results was observed. Results Compared with total body irradiation(TBI), TMI could significantly reduce the irradiation dose to normal tissues. The median dose D50of all normal tissues except the oral cavity were lower than 6 Gy,where The D50of lens,brain,lung and liver are (1.8±0.1) Gy, (5.7±0.2) Gy, (5.2±0.2) Gy, and (4.6±0.2) Gy, respectively. Pass rate of γ Index was larger than 95% with 3mm/3% criterian for each section. The positioning error of head and neck was relatively lower than that of pelvis at x-axis,and was higher at z-axis.Conclusions Helical tomotherapy based TMI is a feasible and reasonable approach,which has evident dosimetric advantage.