title: Quantification of coronary artery motion and internal risk volume from ECG gated radiotherapy planning scans.
abstract: Radiotherapy for carcinoma of breast and thoracic structures involves inadvertent radiation to heart and coronary arteries (CA). Coronary artery stenosis in high radiation dose segments has been documented. Cardiac and respiratory motion induced displacement of CA and internal risk volume (IRV) margin remains inadequately quantified.
  
  
  
  Twenty cases of carcinoma breast, lung and lung metastasis were enrolled in this study. ECG gated intravenous contrast enhanced computed tomography (CECT) scans were performed in inspiratory breath hold (IBH) and expiratory breath hold (EBH). The images were segregated into inspiratory systole (IS), inspiratory diastole (ID), expiratory systole (ES) and expiratory diastole (ED) sets. Left anterior descending (LAD), limited segment of LAD close to chest wall (short LAD), right coronary artery (RCA), Left circumflex artery (LCX) and left ventricle (LV) were delineated in all four sets. Mean displacements in systole versus diastole and inspiration versus expiration were calculated in three co-ordinates [anterio-posterior (Z), left-right (X) and cranio-caudal (Y)].
  
  
  
  Mean of displacement (mm) between systole and diastole (IS versus ID; and ES versus ED) in X, Y, Z co-ordinates were: LAD 3.0(±1.6), 2.8(±1.5), 3.6(±2.0); Short-LAD 3.0(±1.1), 0.8(±0.4), 2.4(±0.6); LV 2.4(±1.6), 1.7(±1), 5.0(±1.5); LCX 4.9(±1.6), 2.9(±1.3), 5.1(±1.9); RCA 6.6(±2.2), 3.6(±2.1), 5.9(±2.2). Mean displacement between inspiration and expiration (IS versus ES; and ID versus ED) in X, Y, Z axes were: LAD 3.3(±1.5), 8.0(±3.4), 3.8(±1.8); Short-LAD 2.7(±1), 12.2(±4.4), 3.3(±1.5); LV 2.9(±1.4), 9.8(±3.3), 4.7(±1.9); LCX 2.9(±.8), 9.7(±3.2), 6.2(±2.5); RCA 2.6(±1.3), 7.6(±2.5), 3.8(±1.7).
  
  
  
  Radial (RM), cranio-caudal margin (CC) of 7mm, 4mm in breath-hold radiotherapy whereas RM, CC of 7mm, 13mm respectively in free breath radiotherapy will cover the range of motions of CA, LV and can be recommended as IRV for these structures.
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Tejinder
authors.initials: T
authors.lastname: Kataria
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Shyam Singh
authors.initials: SS
authors.lastname: Bisht
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Gupta
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Ashu
authors.initials: A
authors.lastname: Abhishek
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Trinanjan
authors.initials: T
authors.lastname: Basu
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Kushal
authors.initials: K
authors.lastname: Narang
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Shikha
authors.initials: S
authors.lastname: Goyal
authors.affiliation: Clinical Oncology, Delhi State Cancer Institute, India.
authors.forename: Pragya
authors.initials: P
authors.lastname: Shukla
authors.affiliation: Cardiology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Bansal
authors.affiliation: Cardiology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Hardeep
authors.initials: H
authors.lastname: Grewal
authors.affiliation: Radiology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Kulbeer
authors.initials: K
authors.lastname: Ahlawat
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Susovan
authors.initials: S
authors.lastname: Banarjee
authors.affiliation: Radiation Oncology, Medanta - The Medicity, Gurgaon, India.
authors.forename: Manoj
authors.initials: M
authors.lastname: Tayal
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D003331:Coronary Vessels / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009038:Motion; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012306:Risk
keywords: Coronary artery motion; ECG gated; IRV; Internal risk volume; Thoracic radiotherapy