title: A CT-assisted method of dosimetry in brachytherapy of lung cancer. Rotterdam Oncological Thoracic Study Group.
abstract: BACKGROUND
  The toxicity of endobronchial brachytherapy (EB), in particular fatal haemoptysis and bronchial wall necrosis, has been correlated with the total dose, fraction size, volume encompassed by the 100% isodose, and a proximal tumor location. We describe a CT-based planning method which, by improving target volume definition and volumetric dose information, can improve the therapeutic ratio of EB.
  
  
  METHODS
  Sixteen CT-assisted EB procedures were performed in patients who were treated with palliative high-dose rate EB. The CT data were used to analyze applicator position in relation to anatomy. An example of a three-dimensional optimized treatment plan was generated and analyzed using different types of dose-volume histograms.
  
  
  RESULTS
  The procedure was well tolerated by patients and no post-procedure complications were observed. The bronchial applicator was eccentrically positioned at the level of the carina/mainstem bronchus in 12 (of 14) CT scans. A planning CT prior to EB was not found to be useful as the final target volume and/or the final applicator position were not reliably predicted before the therapeutic bronchoscopy. CT-scans performed with the applicator in situ allowed the bronchial segments in the target volume to be identified and enabled dose prescription to the bronchial mucosa.
  
  
  CONCLUSIONS
  CT-assisted EB is feasible and underlines the need for using centered applicators for proximally located tumors. By enabling accurate mucosal dose prescription, CT-assisted EB may reduce the toxicity of fractionated EB in the curative setting. However, faster on-line EB treatment planning is needed for the routine clinical application of this technique.
authors.affiliation: Department of Radiation Oncology, University Hospital Rotterdam, Groene Hilledijk 301, 3075 EA, Rotterdam, Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Senan
authors.forename: F J
authors.initials: FJ
authors.lastname: Lagerwaard
authors.forename: C
authors.initials: C
authors.lastname: de Pan
authors.forename: D
authors.initials: D
authors.lastname: Sipkema
authors.forename: S A
authors.initials: SA
authors.lastname: Burgers
authors.forename: L H
authors.initials: LH
authors.lastname: Murrer
mesh_terms: D001918:Brachytherapy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D001980:Bronchi / Q000528:radiation effects; D001995:Bronchography; D001999:Bronchoscopy; D019583:Dose Fractionation, Radiation; D004867:Equipment Design; D005240:Feasibility Studies; D006469:Hemoptysis / Q000209:etiology; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D009336:Necrosis; D009862:Online Systems; D010166:Palliative Care; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D015203:Reproducibility of Results; D020545:Respiratory Mucosa / Q000528:radiation effects; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000000981:diagnostic imaging / Q000528:radiation effects