title: Dependence of coronary 3-dimensional dose maps on coronary topologies and beam set in breast radiation therapy: a study based on CT angiographies.
abstract: OBJECTIVE
  In left-side breast radiation therapy (RT), doses to the left main (LM) and left anterior descending (LAD) coronary arteries are usually assessed after delineation by prior anatomic knowledge on the treatment planning computed tomography (CT) scan. In this study, dose sensitivity due to interindividual coronary topology variation was assessed, and hot spots were located.
  
  
  METHODS
  Twenty-two detailed heart models, created from heart computed tomography angiographies, were fitted into a single representative female thorax. Two breast RT protocols were then simulated into a treatment planning system: the first protocol comprised tangential and tumoral bed beams (TGs_TB) at 50 + 16 Gy, the second protocol added internal mammary chain beams at 50 Gy to TGs_TB (TGs_TB_IMC). For the heart, the LAD, and the LM, several dose indicators were calculated: dose-volume histograms, mean dose (Dmean), minimal dose received by the most irradiated 2% of the volume (D2%), and 3-dimensional (3D) dose maps. Variations of these indicators with anatomies were studied.
  
  
  RESULTS
  For the LM, the intermodel dispersion of Dmean and D2% was 10% and 11%, respectively, with TGs_TB and 40% and 80%, respectively, with TGs_TB_IMC. For the LAD, these dispersions were 19% (Dmean) and 49% (D2%) with TGs_TB and 35% (Dmean) and 76% (D2%) with TGs_TB_IMC. The 3D dose maps revealed that the internal mammary chain beams induced hot spots between 20 and 30 Gy on the LM and the proximal LAD for some coronary topologies. Without IMC beams, hot spots between 5 and 26 Gy are located on the middle and distal LAD.
  
  
  CONCLUSIONS
  Coronary dose distributions with hot spot location and dose level can change significantly depending on coronary topology, as highlighted by 3D coronary dose maps. In clinical practice, coronary imaging may be required for a relevant coronary dose assessment, especially in cases of internal mammary chain irradiation.
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d'Evaluation de la Dose Interne, Fontenay-aux-Roses, France. Electronic address: alexandra.moignier@gmail.com.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Moignier
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d'Evaluation de la Dose Interne, Fontenay-aux-Roses, France.
authors.forename: David
authors.initials: D
authors.lastname: Broggio
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SER/UEM, Unité d'Expertise en radioprotection Médicale, Fontenay-aux-Roses, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Derreumaux
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d'Evaluation de la Dose Interne, Fontenay-aux-Roses, France.
authors.forename: Fida
authors.initials: F
authors.lastname: El Baf
authors.affiliation: Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Service de Radiothérapie Oncologique, Paris, France.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Mandin
authors.affiliation: Institut Gustave Roussy, Service de Radiothérapie Oncologique, Villejuif, France.
authors.forename: Théodore
authors.initials: T
authors.lastname: Girinsky
authors.affiliation: Centre Chirurgical Marie-Lannelongue, Service de Radiologie, Le Plessis-Robinson, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Paul
authors.affiliation: Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Service de Radiothérapie Oncologique, Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Chea
authors.affiliation: Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Service de Radiothérapie Oncologique, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Jenny
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d'Evaluation de la Dose Interne, Fontenay-aux-Roses, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Franck
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SER/UEM, Unité d'Expertise en radioprotection Médicale, Fontenay-aux-Roses, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Aubert
authors.affiliation: Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Service de Radiothérapie Oncologique, Paris, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Mazeron
mesh_terms: D001011:Aorta / Q000033:anatomy & histology; D001027:Aortography / Q000379:methods; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000528:radiation effects; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008323:Mammary Arteries / Q000000981:diagnostic imaging* / Q000528:radiation effects; D008953:Models, Anatomic; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden