title: Cardiac motion during deep-inspiration breath-hold: implications for breast cancer radiotherapy.
abstract: OBJECTIVE
  Many patients with left-sided breast cancer receive adjuvant radiotherapy during deep-inspiration breath hold (DIBH) to minimize radiation exposure to the heart. We measured the displacement of the left anterior descending artery (LAD) and heart owing to cardiac motion during DIBH, relative to the standard tangential fields for left breast cancer radiotherapy.
  
  
  METHODS
  A total of 20 patients who had undergone computed tomography-based coronary angiography with retrospective electrocardiographic gating were randomly selected for the present study. The patients underwent scanning during DIBH to control the influence of respiration on cardiac motion. Standard medial and lateral tangential fields were placed, and the LADs were contoured on the systolic- and diastolic-phase computed tomography data sets by the clinicians. Displacement of the LAD during cardiac contractions was calculated in three directions: toward the posterior edge of the treatment fields, left-right, and anteroposterior. Displacement of the entire heart was measured on the maximal and minimal intensity projection computed tomography images.
  
  
  RESULTS
  The mean displacement of the LAD from cardiac contraction without the influence of respiration for 20 patients was 2.3 mm (range, 0.7-3.8) toward the posterior edge of the treatment fields, 2.6 mm (range, 1.0-6.8) in the left-right direction, and 2.3 mm (range, 0.6-6.5) in the anteroposterior direction. At least 30% of the LAD volume was displaced >5 mm in any direction in 2 patients (10%), and <10% of the LAD volume was displaced >5 mm in 10 patients (50%). The extent of displacement of the heart periphery during cardiac motion was negligible near the treatment fields.
  
  
  CONCLUSIONS
  Displacement of the heart periphery near the treatment fields was negligible during DIBH; however, displacement of the LAD from cardiac contraction varied substantially between and within patients. We recommend maintaining ≥ 5 mm of distance between the LAD and the field edge for patients undergoing breast cancer radiotherapy during DIBH.
authors: Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors: Xiaochun
authors: X
authors: Wang
authors: Tinsu
authors: T
authors: Pan
authors: Chelsea
authors: C
authors: Pinnix
authors: Sean X
authors: SX
authors: Zhang
authors: Mohammad
authors: M
authors: Salehpour
authors: Tzouh Liang
authors: TL
authors: Sun
authors: Gregory
authors: G
authors: Gladish
authors: Eric A
authors: EA
authors: Strom
authors: George H
authors: GH
authors: Perkins
authors: Welela
authors: W
authors: Tereffe
authors: Wendy
authors: W
authors: Woodward
authors: Karen E
authors: KE
authors: Hoffman
authors: Thomas A
authors: TA
authors: Buchholz
authors: T Kuan
authors: TK
authors: Yu
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000502:physiology*; D005260:Female; D006321:Heart; D006801:Humans; D001239:Inhalation; D009068:Movement / Q000502:physiology*; D009200:Myocardial Contraction; D018714:Radiotherapy, Adjuvant; D014057:Tomography, X-Ray Computed / Q000379:methods