title: [Dosimetric impact of breath-hold in the treatment of hepatocellular carcinoma by conformal radiation therapy].
abstract: OBJECTIVE
  To evaluate the dosimetric impact of breath-hold during radiotherapy of hepatocellular carcinoma (HCC) and to determinate the optimal respiratory phase for treatment (exhale or inhale).
  
  
  METHODS
  Two CT scans were performed in inhale and in exhale in 20 patients with HCC. The GTV was delineated slice by slice on the inspiration breath hold acquisition (GTV(insp)) and on the expiration breath hold acquisition (GTV(exp)). The superposition of two GTV allowed to obtain the global GTV (free respiration). PTV was defined by adding a margin of 1cm around each GTV. The liver, the duodenum, the two kidneys, the stomach and the spinal cord were delineated on each acquisition as organs at risk (OAR). Three dosimetric plans were created on inspiration, expiration and on global PTV.
  
  
  RESULTS
  The mean reduction in the volume of PTV with conformal radiation therapy (3D-CRT) in the hold-breath group compared to the free respiration group was of 33.5+/-11.9%. The average difference of V50%, V20, V30, V40 and V50 were around 4% in favor of the breath hold. The average value of NTCP was 8.9% in free respiration, 4.5% in expiration and 3.2% in inspiration. Further improvement in the OARs dosimetric parameters for the breath hold was observed.
  
  
  CONCLUSIONS
  Compared to the conformal radiotherapy with free respiration, the breath-hold allows reducing the volume of the PTV and the doses to the healthy liver and organs at risk. The use of this modality during different radiotherapy techniques (3D-CRT, IMRT and stereotactic) may be recommended. No difference in dosimetric value has been observed between the breath hold in expiratory and inspiratory phases.
authors.affiliation: Service de radiothérapie-oncologie, centre hospitalier Lyon-Sud Pierre-Bénite, 165, chemin du Grand-Revoyet, 69495 Pierre-Bénite cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Kubas
authors.forename: O
authors.initials: O
authors.lastname: Chapet
authors.forename: P
authors.initials: P
authors.lastname: Merle
authors.forename: F
authors.initials: F
authors.lastname: Lorchel
authors.forename: A
authors.initials: A
authors.lastname: d'Hombres
authors.forename: F
authors.initials: F
authors.lastname: Mornex
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D003287:Contrast Media; D004386:Duodenum / Q000000981:diagnostic imaging / Q000528:radiation effects; D045853:Exhalation; D005602:France; D006801:Humans; D001239:Inhalation; D007472:Iohexol / Q000031:analogs & derivatives; D007668:Kidney / Q000000981:diagnostic imaging / Q000528:radiation effects; D008099:Liver / Q000000981:diagnostic imaging / Q000528:radiation effects; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*; D018570:Risk Assessment; D013116:Spinal Cord / Q000000981:diagnostic imaging / Q000528:radiation effects; D013270:Stomach / Q000000981:diagnostic imaging / Q000528:radiation effects; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D003287:Contrast Media; C093233:iobitridol; D007472:Iohexol