title: Minimal benefit of respiratory-gated radiation therapy in the management of thoracic malignancy.
abstract: BACKGROUND
  Respiratory-gated radiotherapy (RGRT) is used in several centres around the world. However, there is continuing controversy regarding the benefit of this technique. The aims of this study are to quantify the dosimetric benefits and the potential predictive factors.
  
  
  METHODS
  Thirty-four consecutive patients were planned using the RGRT and the Free Breathing (FB) approach and compared with regard to target volume coverage and normal tissue parameters. Potential predictive factors were also evaluated.
  
  
  RESULTS
  Tumour coverage was similar 94.4% versus 95.5%. Use of RGRT was not associated with a significant reduction in spinal cord, oesophagus or cardiac dosimetric parameters. However, it did reduce the lung mean dose by 1.33 Gy (P < 0.001) and V20 by 2.2% (P < 0.001). Only superior/inferior displacement of >1 cm was predictive of a >5% reduction in lung V20 parameter, and these patients all had a gross tumour volume (GTV) of <100 cm(3).
  
  
  CONCLUSIONS
  The dosimetric benefit of applying RGRT is small when applied in an unselected population of patients. Superior/inferior displacement of >1 cm for tumours with GTV less than 100 cm(3) may be used to select patients who may derive a >5% reduction in lung V20 parameters.
authors.affiliation: Department of Radiation Oncology, Westmead Hospital, Sydney, New South Wales, Australia; Department of Radiation Oncology, Nepean Hospital, Sydney, New South Wales, Australia; Cancer Care Centre, St George Hospital, Sydney, New South Wales, Australia.
authors.forename: Eric
authors.initials: E
authors.lastname: Hau
authors.forename: Melissa
authors.initials: M
authors.lastname: Rains
authors.forename: Lois
authors.initials: L
authors.lastname: Browne
authors.forename: Rebecca
authors.initials: R
authors.lastname: Muirhead
authors.forename: Roland
authors.initials: R
authors.lastname: Yeghiaian-Alvandi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001822:Body Burden; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D018570:Risk Assessment; D013899:Thoracic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
keywords: dosimetry; radiation; respiratory gating; thoracic malignancy