title: Dosimetric uncertainties of three-dimensional dose reconstruction from two-dimensional data in a multi-institutional study.
abstract: Inconsistencies in the treatment planning process leading to dosimetric uncertainties may affect conclusions drawn from interinstitutional radiation oncology clinical trials. The purpose of this study was to assess the dosimetric uncertainties resulting from the process of reconstructing three-dimensional dose distributions from two-dimensional treatment plan information provided by participating institutions in a randomized clinical trial. This study was based on American College of Radiology Protocol #427, Locally Advanced Multi-Modality Protocol; a multi-institutional phase II randomized study involving radiation therapy for patients with inoperable non-small cell lung cancer. Several sources of dosimetric uncertainty were identified and analyzed, including image quality of hard-copy computed tomography (CT) images, slice spacing of CT scans, treatment position, interpretations of target volumes by radiation oncologists, the contouring of normal anatomic structures, and the use of common beam models for all dose calculations. Each source of uncertainty was investigated using a set of plans, with the ideal characteristics of digital images with 3-mm axial slice spacing and a flat couch, consisting of eight cases from Vanderbilt University Medical Center with electronically transferred CT data. The target volume DVH values were dependent on the additional uncertainty introduced by differences in delineation of the target volumes by the participating radiation oncologists. The DVH values for the lungs and heart were dependent on image quality and treatment position. Esophagus DVH values were not dependent on any of the sources of uncertainty. None of the structure DVH values were dependent on slice thickness or variations in the contouring of normal anatomic structures. Reconstruction of three-dimensional dose distributions from two-dimensional treatment plan information may be useful in cases for which digital CT data is not available or for historical data review. However, dosimetric accuracy will depend on image quality of the treatment planning CT data and consistency in the delineation of tumor volumes.
authors.affiliation: Department of Radiation Oncology, The Vanderbilt Clinic, Vanderbilt University Medical Center, Nashville, Tennessee, USA. rweinber@mdanderson.org
authors.forename: Rebecca
authors.initials: R
authors.lastname: Weinberg
authors.forename: Darryl G L
authors.initials: DG
authors.lastname: Kaurin
authors.forename: Hak
authors.initials: H
authors.lastname: Choy
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
authors.forename: Robert
authors.initials: R
authors.lastname: MacRae
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Jaechul
authors.initials: J
authors.lastname: Kim
authors.forename: Susan L
authors.initials: SL
authors.lastname: Tucker
authors.forename: Philip D
authors.initials: PD
authors.lastname: Bonomi
authors.forename: Chandra
authors.initials: C
authors.lastname: Belani
authors.forename: George
authors.initials: G
authors.lastname: Starkschall
mesh_terms: D001822:Body Burden; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology
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