Technical aspects of the integration of three-dimensional treatment planning dose parameters (GEC-ESTRO Working Group) into pre-implant planning for LDR gynecological interstitial brachytherapy.
This study investigates the technical feasibility of pre-implant image-based treatment planning for LDR GYN interstitial brachytherapy(IB) based on the GEC-ESTRO guidelines. Initially, a virtual plan is generated based on the prescription dose and GEC-ESTRO defined OAR dose constraints with a pre-implant CT. After the actual implant, a regular diagnostic CT was obtained and fused with our pre-implant scan/initial treatment plan in our planning software. The Flexi-needle position changes, and treatment plan modifications were made if needed. Dose values were normalized to equivalent doses in 2 Gy fractions (LQED 2 Gy) derived from the linear-quadratic model with alpha/beta of 3 for late responding tissues and alpha/beta of 10 for early responding tissues. D(90) to the CTV, which was gross tumor (GTV) at the time of brachytherapy with a margin to count for microscopic disease, was 84.7 +/- 4.9% of the prescribed dose. The OAR doses were evaluated by D(2cc) (EBRT+IB). Mean D(2cc) values (LQED(2Gy)) for the rectum, bladder, sigmoid, and small bowel were the following: 63.7 +/- 8.4 Gy, 61.2 +/- 6.9 Gy, 48.0 +/- 3.5 Gy, and 49.9 +/- 4.2 Gy. This study confirms the feasibility of applying the GEC-ESTRO recommended dose parameters in pre-implant CT-based treatment planning in GYN IB. In the process, this pre-implant technique also demonstrates a good approximation of the target volume dose coverage, and doses to the OARs.
Chi
A
A
Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL 60153, USA. achi@lumc.edu
Gao
M
M
Nguyen
N P
NP
Albuquerque
K
K
D001918:Brachytherapy / Q000379:methods*; D005260:Female; D005833:Genital Neoplasms, Female / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed