Elective clinical target volumes for conformal therapy in anorectal cancer: a radiation therapy oncology group consensus panel contouring atlas.
OBJECTIVE
To develop a Radiation Therapy Oncology Group (RTOG) atlas of the elective clinical target volume (CTV) definitions to be used for planning pelvic intensity-modulated radiotherapy (IMRT) for anal and rectal cancers.


METHODS
The Gastrointestinal Committee of the RTOG established a task group (the nine physician co-authors) to develop this atlas. They responded to a questionnaire concerning three elective CTVs (CTVA: internal iliac, presacral, and perirectal nodal regions for both anal and rectal case planning; CTVB: external iliac nodal region for anal case planning and for selected rectal cases; CTVC: inguinal nodal region for anal case planning and for select rectal cases), and to outline these areas on individual computed tomographic images. The imaging files were shared via the Advanced Technology Consortium. A program developed by one of the co-authors (I.E.N.) used binomial maximum-likelihood estimates to generate a 95% group consensus contour. The computer-estimated consensus contours were then reviewed by the group and modified to provide a final contouring consensus atlas.


RESULTS
The panel achieved consensus CTV definitions to be used as guidelines for the adjuvant therapy of rectal cancer and definitive therapy for anal cancer. The most important difference from similar atlases for gynecologic or genitourinary cancer is mesorectal coverage. Detailed target volume contouring guidelines and images are discussed.


CONCLUSIONS
This report serves as a template for the definition of the elective CTVs to be used in IMRT planning for anal and rectal cancers, as part of prospective RTOG trials.
Myerson
Robert J
RJ
Department of Radiation Oncology, Washington University, St Louis, MO, USA. myerson@radonc.wustl.edu
Garofalo
Michael C
MC
El Naqa
Issam
I
Abrams
Ross A
RA
Apte
Aditya
A
Bosch
Walter R
WR
Das
Prajnan
P
Gunderson
Leonard L
LL
Hong
Theodore S
TS
Kim
J J John
JJ
Willett
Christopher G
CG
Kachnic
Lisa A
LA
D001005:Anus Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D006801:Humans; D007085:Ilium; D007264:Inguinal Canal / Q000000981:diagnostic imaging; D016013:Likelihood Functions; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008488:Medical Illustration; D010388:Pelvis; D018787:Radiation Oncology / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods / Q000592:standards*; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D012007:Rectum / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed