An evaluation of the variability of tumor-shape definition derived by experienced observers from CT images of supraglottic carcinomas (ACRIN protocol 6658).

PURPOSE Accurate target definition is considered essential for sophisticated, image-guided radiation therapy; however, relatively little information has been reported that measures our ability to identify the precise shape of targets accurately. We decided to assess the manner in which eight "experts" interpreted the size and shape of tumors based on "real-life" contrast-enhanced computed tomographic (CT) scans. METHODS AND MATERIALS Four neuroradiologists and four radiation oncologists (the authors) with considerable experience and presumed expertise in treating head-and-neck tumors independently contoured, slice-by-slice, his/her interpretation of the precise gross tumor volume (GTV) on each of 20 sets of CT scans taken from 20 patients who previously were enrolled in Radiation Therapy Oncology Group protocol 91-11. RESULTS The average proportion of overlap (i.e., the degree of agreement) was 0.532 (95% confidence interval 0.457 to 0.606). There was a slight tendency for the proportion of overlap to increase with increasing average GTV. CONCLUSIONS Our work suggests that estimation of tumor shape currently is imprecise, even for experienced physicians. In consequence, there appears to be a practical limit to the current trend of smaller fields and tighter margins.

[1]  J. Dimopoulos,et al.  Systematic evaluation of MRI findings in different stages of treatment of cervical cancer: potential of MRI on delineation of target, pathoanatomic structures, and organs at risk. , 2006, International journal of radiation oncology, biology, physics.

[2]  G. Cook,et al.  Positron emission tomography for target volume definition in the treatment of non-small cell lung cancer. , 2005, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[3]  J. Fowler,et al.  Image guidance for precise conformal radiotherapy. , 2003, International journal of radiation oncology, biology, physics.

[4]  Dwight E Heron,et al.  Advances in image-guided radiation therapy--the role of PET-CT. , 2006, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[5]  Cedric X. Yu,et al.  Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT Subcommittee of the AAPM Radiation Therapy Committee. , 2003, Medical physics.

[6]  D. Hahn,et al.  Tumor volume as determined by computed tomography predicts local control in hypopharyngeal squamous cell carcinoma treated with primary surgery , 2004, European Radiology.

[7]  R. Weber,et al.  Concurrent chemotherapy and radiotherapy for organ preservation in advanced laryngeal cancer. , 2003, The New England journal of medicine.

[8]  Alicia Y Toledano,et al.  Interobserver reliability of computed tomography‐derived primary tumor volume measurement in patients with supraglottic carcinoma , 2005, Cancer.

[9]  W. Mendenhall,et al.  Parameters that predict local control after definitive radiotherapy for squamous cell carcinoma of the head and neck , 2003, Head & neck.

[10]  Bram Stieltjes,et al.  Functional magnetic resonance imaging for defining the biological target volume , 2006, Cancer imaging : the official publication of the International Cancer Imaging Society.

[11]  W. Tomé,et al.  Variations in target delineation for head and neck IMRT: An international multi-institutional study , 2004 .

[12]  W. Mendenhall,et al.  The impact of primary tumor volume on local control for oropharyngeal squamous cell carcinoma treated with radiotherapy , 2000, Head & neck.

[13]  Philippe Lambin,et al.  The current status of FDG-PET in tumour volume definition in radiotherapy treatment planning. , 2006, Cancer treatment reviews.

[14]  T. Leong,et al.  Influence of F-fluorodeoxyglucose-positron emission tomography on computed tomography-based radiation treatment planning for oesophageal cancer. , 2006, Australasian radiology.