3D-Conformal versus intensity-modulated postoperative radiotherapy of vaginal vault: A dosimetric comparison.
We evaluated a step-and-shoot IMRT plan in the postoperative irradiation of the vaginal vault compared with equispaced beam arrangements (3-5) 3D-radiotherapy (RT) optimized plans. Twelve patients were included in this analysis. Four plans for each patient were compared in terms of dose-volume histograms, homogeneity index (HI), and conformity index (CI): (1) 3 equispaced beam arrangement 3D-RT; (2) 4 equispaced beam arrangement 3D-RT; (3) 5 equispaced beam arrangement 3D-RT; (4) step-and-shoot IMRT technique. CI showed a good discrimination between the four plans. The mean scores of CI were 0.58 (range: 0.38-0.67) for the 3F-CRT plan, 0.58 (range: 0.41-0.66) for 4F-CRT, 0.62 (range: 0.43-0.68) for 5F-CRT and 0.69 (range: 0.58-0.78) for the IMRT plan. A significant improvement of the conformity was reached by the IMRT plan (p < 0.001 for all comparisons). As expected, the increment of 3D-CRT fields was associated with an improvement of target dose conformity and homogeneity; on the contrary, in the IMRT plans, a better conformity was associated to a worse target dose homogeneity. A significant reduction in terms of D(mean), V90%, V95%, V100% was recorded for rectal and bladder irradiation with the IMRT plan. Surprisingly, IMRT supplied a significant dose reduction also for rectum and bladder V30% and V50%. A significant dosimetric advantage of IMRT over 3D-RT in the adjuvant treatment of vaginal vault alone in terms of treatment conformity and rectum and bladder sparing is shown.
Cilla
Savino
S
Department of Oncology, "John Paul II" Center for High Technology Research and Education in Biomedical Sciences, Catholic University, Campobasso, Italy.
Macchia
Gabriella
G
Digesù
Cinzia
C
Deodato
Francesco
F
Romanella
Michele
M
Ferrandina
Gabriella
G
Padula
Gilbert D A
GD
Picardi
Vincenzo
V
Scambia
Giovanni
G
Piermattei
Angelo
A
Morganti
Alessio Giuseppe
AG
D000368:Aged; D002277:Carcinoma / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D016889:Endometrial Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D005260:Female; D006801:Humans; D007044:Hysterectomy; D008875:Middle Aged; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D018714:Radiotherapy, Adjuvant; D050397:Radiotherapy, Intensity-Modulated; D016896:Treatment Outcome