title: Conformal radiotherapy planning for lung cancer: analysis of set-up uncertainties.
abstract: The objective of this study was to evaluate set-up uncertainties using a portal imaging system in a population of inoperable non-small cell lung cancer. Twenty-one patients were treated by a conformal radiotherapy technique with a personalized immobilization cast. The beam was verified by comparison with a corresponding digitally reconstructed radiograph by superimposition of anatomical structures. One thousand eight hundred eighty three images were analyzed. The mean intrafraction and interfraction errors (+/-SD) were 2.17 mm and 0.9 +/- 3.7 mm, 2.3 mm and 0.9 +/- 3.1 mm, 3 mm and 0.7 +/- 3 mm on the lateral (x), cranio-caudal (y) and anterior-posterior (z) axes, respectively. The mean systematic error was small, less than 1 mm, in all directions. The random errors were 2.5 mm, 2.4 mm, and 1.8 mm on the x, y, and z axes, respectively. No correlation between errors and the patient's height, weight, age, or sex was found. Set-up errors accuracy depending on practices, each institution should review their own treatments to quantify and reduce set-up errors in clinical practice.
authors.affiliation: Departments of Oncology-Radiotherapy, Institut Curie, Paris, France. philippe.giraud@curie.net
authors.forename: Philippe
authors.initials: P
authors.lastname: Giraud
authors.forename: Yann
authors.initials: Y
authors.lastname: De Rycke
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Rosenwald
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Cosset
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D003952:Diagnostic Imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008175:Lung Neoplasms / Q000532:radiotherapy*; D015588:Observer Variation; D011832:Radiation Injuries / Q000517:prevention & control; D020266:Radiotherapy, Conformal / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012149:Restraint, Physical / Q000295:instrumentation / Q000379:methods; D014057:Tomography, X-Ray Computed; D035501:Uncertainty