title: Evaluation of a laser system for CT software simulation (EXOMIO) in patients with breast cancer.
abstract: OBJECTIVE
  To develop a manually movable laser system connected to the CT table for alignment of the isocenter cross of irradiation fields on the patient's skin directly after CT software simulation.
  
  
  METHODS
  The specially designed laser system was constructed in the authors' department, and the mean focusing accuracy of isocenter translations was analyzed using Alderson phantom measurements. The mean overall accuracy from setup to treatment of the whole procedure of CT software simulation was measured by the comparison of bone structures and mamma contour of the digitally reconstructed radiograph (DRR) with the verification film. The time taken for the different setup procedure steps was evaluated for 70 breast cancer patients who were treated using tangential fields.
  
  
  RESULTS
  The mean focusing accuracy of the manually movable laser system after defined isocenter translation was measured as 0.8 +/- 0.5 mm, the mean patient movement on the CT table as 2.0 +/- 1 mm, and the mean positioning accuracy of the first treatment after patient positioning corresponding to the skin alignments as 3.9 +/- 1.5 mm. The time periods for the different steps of the CT software simulation were measured, and the total duration was found to be 35.8 +/- 3.3 min.
  
  
  CONCLUSIONS
  In general, the main advantage of well-known CT software simulation when compared to conventional simulation is the relief of the real X-ray simulator which is feasible with fast planning software (EXOMIO) and the presented movable laser system.
authors.affiliation: Department of Radiation Oncology, University of Marburg, Marburg, Germany. strassma@med.uni-marburg.de
authors.forename: Gerd
authors.initials: G
authors.lastname: Strassmann
authors.forename: Peter
authors.initials: P
authors.lastname: Vacha
authors.forename: Torsten
authors.initials: T
authors.lastname: Osterhaus
authors.forename: Anke
authors.initials: A
authors.lastname: Battmann
authors.forename: Detlev
authors.initials: D
authors.lastname: Richter
authors.forename: Kamal
authors.initials: K
authors.lastname: Nashwan
authors.forename: Hans Otto
authors.initials: HO
authors.lastname: Neidel
authors.forename: Klaus Jochen
authors.initials: KJ
authors.lastname: Klose
authors.forename: Rita
authors.initials: R
authors.lastname: Engenhart-Cabillic
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D007834:Lasers; D008875:Middle Aged; D009038:Motion; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods