title: Electron arc therapy for bilateral chest wall irradiation: treatment planning and dosimetric study.
abstract: OBJECTIVE
  The treatment of patients with synchronous bilateral breast cancer is a challenge. We present a report of dosimetric data of patients with bilateral chest walls as the target treated with electron arc therapy.
  
  
  METHODS
  Ten consecutive patients who had undergone electron arc therapy to the bilateral chest wall for breast cancer were analysed. After positioning and immobilisation, patients underwent computed tomography scans from the neck to the upper abdomen. Electron arc plans were generated using the PLATO RTS (V1.8.2 Nucletron) treatment planning system. Electron energy was chosen depending upon the depth and thickness of the planning target volume (PTV). For all patients, the arc angle ranged between 80 and 280° (start angle 80°, stop angle 280°). The homogeneity index, coverage index and doses to organs at risk were evaluated. The patient-specific output factor and thermoluminescence dosimetry (TLD) measurements were carried out for all patients. The total planned dose to the PTV was 50Gy/25 fractions/5 weeks.
  
  
  RESULTS
  The mean PTV (± standard deviation) was 568.9 (±116)cm(3). The mean PTV coverage was 89 (±5.8)% of the prescribed dose. For the right lung, the mean values of D(1) and D(10) were 46 (±7.6) and 30 (±9)Gy, respectively. For the left lung, the mean values of D(1) and D(10) were 45 (±7) and 27 (±8)Gy, respectively. For the heart, the mean values of D(1), D(5) and D(10) were 21 (±15), 13.5 (±12) and 9 (±9)Gy, respectively. The mean values of TLD at various pre-specified locations on the chest wall surface were 1.84, 1.82, 1.82, 1.89 and 1.78Gy, respectively
  
  
  CONCLUSIONS
  The electron arc technique for treating the bilateral chest wall is a feasible and pragmatic technique. This technique has the twin advantages of adequate coverage of the target volume and sparing of adjacent normal structures. However, compared with other techniques, it needs a firm quality assurance protocol for dosimetry and treatment delivery.
authors.affiliation: Department of Medical Physics & Radiation Safety, International Oncology Centre, Fortis Hospital, Noida, India.
authors.forename: P K
authors.initials: PK
authors.lastname: Sharma
authors.forename: S V
authors.initials: SV
authors.lastname: Jamema
authors.forename: K
authors.initials: K
authors.lastname: Kaushik
authors.forename: A
authors.initials: A
authors.lastname: Budrukkar
authors.forename: R
authors.initials: R
authors.lastname: Jalali
authors.forename: D D
authors.initials: DD
authors.lastname: Deshpande
authors.forename: C M
authors.initials: CM
authors.lastname: Tambe
authors.forename: R
authors.initials: R
authors.lastname: Sarin
authors.forename: A
authors.initials: A
authors.lastname: Munshi
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D011874:Radiometry; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D035441:Thoracic Wall / Q000528:radiation effects*