title: Development of delineation for the left anterior descending coronary artery region in left breast cancer radiotherapy: An optimized organ at risk.
abstract: The left anterior descending coronary artery (LAD) and diagonal branches (DBs) are blurred on computed tomography (CT). We aimed to define the LAD region (LADR) with adequate inclusion of the LAD and DBs and contouring consistency.
  
  
  
  The LADR was defined using coronary CT angiograms. The inclusion ratio was used to assess the LAD and DBs inclusion by the LADR. Four radiation oncologists delineated the LAD and LADR, using contrast-enhanced CT of 15 patients undergoing left breast radiotherapy. The Sørensen-Dice similarity index (DSI), Jaccard similarity index (JSI), and Hausdorff distance (HD) were calculated to assess similarity. The mean dose (Dmean) and maximum dose (Dmax) to the LAD and LADR were calculated to compare consistency. Correlations were evaluated using Pearson's correlation coefficient.
  
  
  
  The inclusion ratio of the LAD by the LADR was 96%. The mean DSI, JSI, and HD values were respectively 27.9%, 16.7%, and 0.42mm for the LAD, and 83.1%, 73.0%, and 0.18mm for the LADR. The Dmeanbetween the LAD and LADR were strongly correlated (r=0.93).
  
  
  
  Delineation of the LADR significantly improved contouring similarity and consistency for dose reporting. This could optimize dose estimation for breast radiotherapy.
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, Taiwan; Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Jie
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Computer Science and Information Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors.forename: Kai-Lung
authors.initials: KL
authors.lastname: Hua
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Hsu
authors.affiliation: Department of Radiation Oncology, Changhua Christian Hospital, Taiwan.
authors.forename: Jhen-Bin
authors.initials: JB
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, E-Da Cancer Hospital, Kaohsiung, Taiwan.
authors.forename: Chou-Hsien
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Lu
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Kun-Yao
authors.initials: KY
authors.lastname: Dai
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Xu-Nian
authors.initials: XN
authors.lastname: Huang
authors.affiliation: Department of Radiology, MacKay Memorial Hospital, Taipei, Taiwan.
authors.forename: Jun-Zhao
authors.initials: JZ
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, Taiwan. Electronic address: radionc1@gmail.com.
authors.forename: Meng-Hao
authors.initials: MH
authors.lastname: Wu
authors.affiliation: Department of Radiation Oncology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, Taiwan. Electronic address: chenmdphd@gmail.com.
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D000072226:Computed Tomography Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk; D056888:Patient Positioning; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods
keywords: Coronary artery; Left breast cancer; Radiotherapy