Three-dimension anatomy-based planning optimization for high dose rate vaginal vault brachytherapy.
OBJECTIVE
To retrospectively compare 3-dimension (3D)-inverse planning optimization with 2 conventional planning methods in vaginal vault high-dose-rate brachytherapy.


METHODS
We randomly selected 26 patients with endometrium cancer, treated with external beam radiotherapy followed by intracavitary high-dose-rate brachytherapy. The study was carried out in the Radiotherapy Unit of King Abdulaziz University Hospital, Jeddah, Saudi Arabia between July 2010 and October 2011. For each brachytherapy fraction, dose-volume-histograms were analyzed for 3 different dose prescription protocols: 0.5 cm from the applicator's tip, 0.5 cm along the applicator's surface, and inverse planning.


RESULTS
Dose-volume-histogram analysis showed a significant difference (p<0.001) between the 3 treatment planning methods regarding clinical-target-volume prescribed dose coverage: 26.7%+/-5.4%  versus 48.5%+/-6.7% versus 68.6%+/-7.5%. The doses received by the volumes of 2 cm3 of organs-at-risk were (p<0.001): rectum: 4.6+/-1.1 Gy versus 2.8+/-0.5 Gy versus 3.3+/-0.5 Gy; sigmoid: 1.4+/-0.8 Gy versus 0.7+/-0.3 Gy versus 0.9+/-0.5 Gy; and bladder: 3.7+/-1.0  Gy versus 2.3+/-0.5 Gy, versus 2.7+/-0.6 Gy.


CONCLUSIONS
Three-dimension inverse planning provides the ability to balance the target dose coverage against the sparing of organs at risk. For vaginal vault high-dose-rate inverse planning brachytherapy, the use of a CT scan only for the first fraction of treatment is feasible, and the dosimetric impact is minimal.
Department of Radiology, King Abdulaziz University Hospital, PO Box 80215, Jeddah 21589, Kingdom of Saudi Arabia. yasirbahadur@hotmail.com
Yasir A
YA
Bahadur
Ashraf H
AH
Hassouna
Camelia T
CT
Constantinescu
Adly F
AF
Naga
Noor M
NM
Ghasal
Mohamed E
ME
Elsayed
D001918:Brachytherapy / Q000379:methods; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D012809:Colon, Sigmoid / Q000528:radiation effects; D016889:Endometrial Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005240:Feasibility Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D018579:Patient Selection; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D014621:Vagina / Q000528:radiation effects