Prospective randomized double-blind pilot study of site-specific consensus atlas implementation for rectal cancer target volume delineation in the cooperative group setting

Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
International journal of radiation oncology, biology, physics (Impact Factor: 4.18). 02/2011; 79(2):481-9. DOI: 10.1016/j.ijrobp.2009.11.012
Source: PubMed

ABSTRACT Variations in target volume delineation represent a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the effect of a consensus guideline-based visual atlas on contouring the target volumes.
A representative case was contoured (Scan 1) by 14 physician observers and a reference expert with and without target volume delineation instructions derived from a proposed rectal cancer clinical trial involving conformal radiotherapy. The gross tumor volume (GTV), and two clinical target volumes (CTVA, including the internal iliac, presacral, and perirectal nodes, and CTVB, which included the external iliac nodes) were contoured. The observers were randomly assigned to receipt (Group A) or nonreceipt (Group B) of a consensus guideline and atlas for anorectal cancers and then instructed to recontour the same case/images (Scan 2). Observer variation was analyzed volumetrically using the conformation number (CN, where CN = 1 equals total agreement).
Of 14 evaluable contour sets (1 expert and 7 Group A and 6 Group B observers), greater agreement was found for the GTV (mean CN, 0.75) than for the CTVs (mean CN, 0.46-0.65). Atlas exposure for Group A led to significantly increased interobserver agreement for CTVA (mean initial CN, 0.68, after atlas use, 0.76; p = .03) and increased agreement with the expert reference (initial mean CN, 0.58; after atlas use, 0.69; p = .02). For the GTV and CTVB, neither the interobserver nor the expert agreement was altered after atlas exposure.
Consensus guideline atlas implementation resulted in a detectable difference in interobserver agreement and a greater approximation of expert volumes for the CTVA but not for the GTV or CTVB in the specified case. Visual atlas inclusion should be considered as a feature in future clinical trials incorporating conformal RT.

Download full-text


Available from: Shilpen Patel, Aug 14, 2015
  • Source
    • "Reference No. participants Intervention Method Comments [67] "
    [Show abstract] [Hide abstract]
    ABSTRACT: The global move towards more conformal radiotherapy for rectal cancer requires better imaging modalities that both visualise the disease accurately and are reproducible; to reduce interobserver variation. This review explores the advances in imaging modalities used in target volume delineation, with a view to make recommendations for current clinical practice and to propose future directions for research. A systematic review was conducted using MEDLINE and EMBASE. Articles considered relevant by the authors were included. Planning with orthogonal films is being replaced by computed tomography (CT) simulation. This is now considered the 'gold standard' and allows conformal three-dimensional planning. Magnetic resonance imaging (MRI) has been shown to overcome some of the limitations of CT and can be used either as a diagnostic image to visually aid planning, or as a 'planning' MRI carried out in the treatment position and co-registered with the planning CT. The latter approach has been shown to change the treated volumes compared with CT and in prostate cancer patients has been shown to reduce interobserver variation. There are remaining issues with four-dimensional motion that are yet to be fully appreciated or overcome. 2-[18F] fluoro-2-deoxy-d-glucose positron emission tomography/CT co-registered with planning CT results in smaller volumes than CT alone and also reduces interobserver variation, but requires further validation before routine implementation. Experimental work utilising novel positron emission tomography tracers and diffusion-weighted MRI shows promise and requires further evaluation. Rigorous quality assurance is important with processing of newer imaging modalities. Further work needs to be conducted into both interobserver variation and the formal evaluation of the clinical benefits of newer imaging modalities. Developments in image-guided radiotherapy are also required to ensure that improvements in target definition at the planning stage are reproducible throughout treatment.
    Clinical Oncology 02/2012; 24(1):52-63. DOI:10.1016/j.clon.2011.10.001 · 2.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A media space is currently being constructed which consists of three distinct components: audio/video equipment; groupware presenting a shared workspace; and a distributed software architecture providing layered services to support a variety of modes of cooperation in a highly-interactive work environment. The hardware configuration is described, with comments on the significance of equipment layout and performance, based on previous experience in multimedia conferencing. Initial work on a distributed software architecture is discussed, which will provide appropriate audio/video services layered to support a variety of modes of interaction
    Communications, 1992. ICC '92, Conference record, SUPERCOMM/ICC '92, Discovering a New World of Communications., IEEE International Conference on; 07/1992
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The American College of Radiology (ACR) Appropriateness Criteria on Resectable Rectal Cancer was updated by the Expert Panel on Radiation Oncology-Rectal/Anal Cancer, based on a literature review completed in 2007.
    International Journal of Radiation OncologyBiologyPhysics 04/2008; 70(5):1427-1430. DOI:10.1016/j.ijrobp.2007.09.029 · 4.18 Impact Factor
Show more