title: Rapid automated treatment planning process to select breast cancer patients for active breathing control to achieve cardiac dose reduction.
abstract: OBJECTIVE
  To evaluate a rapid automated treatment planning process for the selection of patients with left-sided breast cancer for a moderate deep inspiration breath-hold (mDIBH) technique using active breathing control (ABC); and to determine the dose reduction to the left anterior descending coronary artery (LAD) and the heart using mDIBH.
  
  
  METHODS
  Treatment plans were generated using an automated method for patients undergoing left-sided breast radiotherapy (n = 53) with two-field tangential intensity-modulated radiotherapy. All patients with unfavorable cardiac anatomy, defined as having >10 cm(3) of the heart receiving 50% of the prescribed dose (V(50)) on the free-breathing automated treatment plan, underwent repeat scanning on a protocol using a mDIBH technique and ABC. The doses to the LAD and heart were compared between the free-breathing and mDIBH plans.
  
  
  RESULTS
  The automated planning process required approximately 9 min to generate a breast intensity-modulated radiotherapy plan. Using the dose-volume criteria, 20 of the 53 patients were selected for ABC. Significant differences were found between the free-breathing and mDIBH plans for the heart V(50) (29.9 vs. 3.7 cm(3)), mean heart dose (317 vs. 132 cGy), mean LAD dose (2,047 vs. 594 cGy), and maximal dose to 0.2 cm(3) of the LAD (4,155 vs. 1,507 cGy, all p <.001). Of the 17 patients who had a breath-hold threshold of ≥ 0.8 L, 14 achieved a ≥ 90% reduction in the heart V(50) using the mDIBH technique. The 3 patients who had had a breath-hold threshold <0.8 L achieved a lower, but still significant, reduction in the heart V(50).
  
  
  CONCLUSIONS
  A rapid automated treatment planning process can be used to select patients who will benefit most from mDIBH. For selected patients with unfavorable cardiac anatomy, the mDIBH technique using ABC can significantly reduce the dose to the LAD and heart, potentially reducing the cardiac risks.
authors.affiliation: Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, ON, Canada. anthony.fyles@rmp.uhn.on.ca
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Purdie
authors.forename: Mohammad
authors.initials: M
authors.lastname: Rahman
authors.forename: Andrea
authors.initials: A
authors.lastname: Marshall
authors.forename: Fei-Fei
authors.initials: FF
authors.lastname: Liu
authors.forename: Anthony
authors.initials: A
authors.lastname: Fyles
mesh_terms: D000328:Adult; D000368:Aged; D001331:Automation / Q000379:methods; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D003331:Coronary Vessels / Q000528:radiation effects*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000528:radiation effects; D006801:Humans; D001239:Inhalation; D008875:Middle Aged; D058958:Organs at Risk / Q000000981:diagnostic imaging* / Q000528:radiation effects; D018579:Patient Selection; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration; D013997:Time Factors; D047368:Tumor Burden