The effect of uterine motion and uterine margins on target and normal tissue doses in intensity modulated radiation therapy of XXXX .

@entity1 @entity19303 @entity202 @entity5 @entity343
In intensity modulated radiation therapy (IMRT) of @entity5 , uterine motion can be larger than cervix motion, requiring a larger clinical target volume to planning target volume (CTV-to- @entity343 ) margin around the uterine fundus. This work simulates different motion models and margins to estimate the dosimetric consequences. A virtual study used image sets from ten @entity1 . Plans were created with uniform margins of 1 cm ( @entity343 (A)) and 2.4 cm ( @entity343 (C)), and a margin tapering from 2.4 cm at the fundus to 1 cm at the cervix ( @entity343 (B)). Three inter-fraction motion models (MM) were simulated. In @entity19303 , all structures moved with normally distributed rigid body translations. In @entity202 , CTV motion was progressively magnified as one moved superiorly from the cervix to the fundus. In MM3, both CTV and normal tissue motion were magnified as in @entity202 , modeling the scenario where normal tissues move into the void left by the mobile uterus. Plans were evaluated using static and percentile DVHs. For a conventional margin ( @entity343 (A)), quasi-realistic uterine motion (MM3) reduces fundus dose by about 5 Gy and increases normal tissue volumes receiving 30-50 Gy by    5%. A tapered CTV-to- @entity343 margin can restore fundus and CTV doses, but will increase normal tissue volumes receiving 30-50 Gy by a further    5%.
