Determination of optimal planning target volume margins in XXXX with gynecological cancer.

@entity1 @entity343 @entity28
PURPOSE: To define optimal planning target volume ( @entity343 ) margins for intensity modulated radiotherapy (IMRT)      knee-heel support (KHS) in @entity1 treated with adjuvant radiotherapy. METHODS: Computed tomography (CT) scans      KHS of 10 @entity1 were taken before and at 3rd and 5th week of treatment, fused and compared with initial IMRT plans. RESULTS: A @entity343 margin of 15  mm in anteroposterior (AP) and superoinferior (SI) directions and 5  mm in lateral directions were found to be adequate without any difference between      KHS except for the SI shifts in CTV-primary at the 3rd week. Five mm margin for iliac CTV was found to be inadequate in 10-20% of @entity1 in SI directions however when 7  mm margin was given for iliac @entity343 , it was found to be adequate. For presacral CTV, it was found that the most striking shift of the target volume was in the direction of AP. KHS caused significantly less volume of rectum and bladder in the treated volume. CONCLUSIONS: @entity343 margin of 15  mm in SI and AP, and 5  mm in lateral directions for CTV-primary were found to be adequate. A minimum of 7  mm @entity343 margin should be given to iliac CTV. The remarkable shifting in presacral CTV was believed to be due to the unforeseen hip malposition of @entity28 @entity1 . The KHS seems not to provide additional beneficial effect in decreasing the shifts both in CTV-primary and lymphatic, however it may have a beneficial effect of decreasing the OAR volume in @entity343 margins.
