title: Is abdominal compression useful in lung stereotactic body radiation therapy? A 4DCT and dosimetric lobe-dependent study.
abstract: OBJECTIVE
  To determine the usefulness of abdominal compression in lung stereotactic body radiation therapy (SBRT) depending on lobe tumor location.
  
  
  METHODS
  Twenty-seven non-small cell lung cancer patients were immobilized in the Stereotactic Body Frame™ (Elekta). Eighteen tumors were located in an upper lobe, one in the middle lobe and nine in a lower lobe (one patient had two lesions). All patients underwent two four-dimensional computed tomography (4DCT) scans, with and without abdominal compression. Three-dimensional tumor motion amplitude was determined using manual landmark annotation. We also determined the internal target volume (ITV) and the influence of abdominal compression on lung dose-volume histograms.
  
  
  RESULTS
  The mean reduction of tumor motion amplitude was 3.5 mm (p = 0.009) for lower lobe tumors and 0.8 mm (p = 0.026) for upper/middle lobe locations. Compression increased tumor motion in 5 cases. Mean ITV reduction was 3.6 cm(3) (p = 0.039) for lower lobe and 0.2 cm(3) (p = 0.048) for upper/middle lobe lesions. Dosimetric gain of the compression for lung sparing was not clinically relevant.
  
  
  CONCLUSIONS
  The most significant impact of abdominal compression was obtained in patients with lower lobe tumors. However, minor or negative effects of compression were reported for other patients and lung sparing was not substantially improved. At our institute, patients with upper or middle lobe lesions are now systematically treated without compression and the usefulness of compression for lower lobe tumors is evaluated on an individual basis.
authors.affiliation: University of Lyon, CREATIS, CNRS UMR 5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France. bouilhol@creatis.insa-lyon.fr
authors.forename: Gauthier
authors.initials: G
authors.lastname: Bouilhol
authors.forename: Myriam
authors.initials: M
authors.lastname: Ayadi
authors.forename: Simon
authors.initials: S
authors.lastname: Rit
authors.forename: Sheeba
authors.initials: S
authors.lastname: Thengumpallil
authors.forename: Joël
authors.initials: J
authors.lastname: Schaerer
authors.forename: Jef
authors.initials: J
authors.lastname: Vandemeulebroucke
authors.forename: Line
authors.initials: L
authors.lastname: Claude
authors.forename: David
authors.initials: D
authors.lastname: Sarrut
mesh_terms: D000005:Abdomen; D016477:Artifacts; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000601:surgery; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000601:surgery*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D055595:Mechanical Phenomena; D011874:Radiometry; D016634:Radiosurgery / Q000379:methods*