title: Simultaneous irradiation of the breast and regional lymph nodes in prone position using helical tomotherapy.
abstract: OBJECTIVE
  We investigated dosimetric advantages of using helical tomotherapy to simultaneously irradiate the breast and regional lymph nodes for patients positioned prone, and compared tomotherapy plan qualities for the prone position with those previously published for the supine position.
  
  
  METHODS
  Tomotherapy plans for 11 patients (5 left breast, 6 right) simulated with the involved breast suspended downward were generated. Each target (ipsilateral breast and supraclavicular, axillary and internal mammary chain nodes) was to receive 45 Gy.
  
  
  RESULTS
  For targets, V(40.5)≥99.9% and V(42.8)≥99.5% for all patients, where V(40.5) and V(42.8) denote the relative target volume receiving at least 40.5 and 42.8 Gy, respectively. The targets' maximum dose was, on average, approximately 49.5 Gy. The mean doses to the contralateral lung and heart were lower for right-breast cases (2.8 Gy lung, 2.7 Gy heart) than for left-breast cases (3.8 Gy lung, 8.7 Gy heart). Mean organ doses to the ipsilateral lung (9.3 Gy) and contralateral breast (2.3 Gy) from the prone breast tomotherapy plans were similar to those reported for conventional radiotherapy techniques. For the left breast with regional nodes, tomotherapy plans for prone-positioned patients yielded lower mean doses to the contralateral breast and heart than previously reported data for tomotherapy plans for supine-positioned patients.
  
  
  CONCLUSIONS
  Helical tomotherapy with prone breast positioning can simultaneously cover the breast and regional nodes with acceptable uniformity and can provide reduced mean dose to proximal organs at risk compared with tomotherapy with supine position. The similarity of plan quality to existing data for conventional breast radiotherapy indicates that this planning approach is appropriate, and that the risk of secondary tumour formation should not be significantly greater.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kainz
authors.forename: J
authors.initials: J
authors.lastname: White
authors.forename: G-P
authors.initials: GP
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Hermand
authors.forename: M
authors.initials: M
authors.lastname: England
authors.forename: X A
authors.initials: XA
authors.lastname: Li
mesh_terms: D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000532:radiotherapy*; D004947:Esophagus / Q000528:radiation effects; D005260:Female; D006321:Heart / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000528:radiation effects; D008198:Lymph Nodes / Q000528:radiation effects; D015182:Lymphatic Irradiation / Q000379:methods*; D008207:Lymphatic Metastasis; D058958:Organs at Risk / Q000528:radiation effects; D056888:Patient Positioning / Q000379:methods*; D016684:Prone Position; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D016683:Supine Position