ABSTRACT
Objective To evaluate the clinical application value of a novel immobilization system in total marrow irradiation ( TMI) with MVCT image. Methods From 2016 to 2017, a retrospective analysis of the setup errors of 22 patients receiving TMI in two groups ( twelve patients were immobilized with the novel immobilization system in group 1, ten patients were immobilized with the combinatorial immobilization devices in group 2) was performed in this study on Zhongnan Hospital of Wuhan University. Two-sample t-test was used to analyze the differences of setup errors and the consistency of setup between two groups. Results In group 1, the setup errors on left-right, superior-inferior, anterior-posterior and rotation directions were ( 1.06±0.79) , ( 1.34±0.66) , ( 2.45±1.48) mm and ( 0.63°±0.65°) for the head and neck position, ( 1.58±1.13) , ( 2.38±1.99) , ( 2.05± 1.68) mm and ( 0.31°± 0.32°) for the chest position, ( 1.67± 1.24) , ( 3.88±2.20) , ( 1.96± 1.32) mm and ( 0.48°± 0.53°) for the pelvis position, and ( 0.95± 0.73) , ( 1.99± 1.35) , ( 3.66±2.13) mm and ( 0.24°±0.31°) for the lower limb, respectively. In group 2, the setup errors were ( 2.59±2.58) , ( 3.28±1.85) , ( 3.71±2.43) mm and ( 1.15°±1.18°) for the head and neck position, ( 4.38±3.69) , ( 5.64±3.78) , ( 2.72± 1.91) mm and ( 1.55°± 0.86°) for the chest position, ( 4.14± 2.97) , ( 6.97±3.68) , ( 2.21±2.26) mm and ( 1.23°±0.74°) for the pelvis position, ( 2.28± 1.15) , ( 5.97± 3.00) , ( 3.44±1.93) mm and ( 1.09°±0.94°) for the lower limb, respectively. The setup errors significantly differed between two groups on the left-right, superior-inferior and rotation directions for all positions ( all P<0.05) . The setup consistency significantly differed between two groups on the left-right, superior-inferior and rotation directions for the chest and pelvis positions ( all P<0.05) . Conclusion The novel immobilization system can significantly improve the setup accuracy and setup consistency, and enhance the precision of treatment for patients.
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.