title: A comparison between 2-Step IMRT and conventional IMRT planning.
abstract: OBJECTIVE
  2-Step intensity modulated radiation therapy (2-Step IMRT) is an IMRT segmentation procedure based on analytical approximations [Bratengeier K. 2-Step IMAT and 2-Step IMRT: a geometrical approach. Med Phys 2005;32:777-785; Bratengeier K. 2-Step IMAT and 2-Step IMRT in three dimensions. Med Phys 2005;32:3849-3861]. The aim was to benchmark it with other IMRT algorithms and to establish it as planning tool for fast IMRT application with a reduced number of segments.
  
  
  METHODS
  2-Step IMRT plans were compared with IMRT-solutions obtained with methods from a commercial planning system (Pinnacletrade mark TPS). The four clinical cases chosen were: paraspinal tumour, carcinoma of the prostate, head and neck carcinoma and breast carcinoma. In addition the "Quasimodo" phantom study was used to compare the quality of the 2-Step IMRT method with respect to other planning procedures in the ESTRO study.
  
  
  RESULTS
  The number of segments (and - to a minor degree - the monitor units per dose) of the majority of 2-Step IMRT plans was lower than for the commercial algorithms. The quality of the 2-Step IMRT-plan was comparable. In the Quasimodo comparison 2-Step IMRT plans with nine beams would place in the mid-range of all participants, whereas the 15-beam arrangements could compete with the best results.
  
  
  CONCLUSIONS
  2-Step IMRT is a valuable IMRT segmentation method, especially if the number of segments is to be limited (e.g. for reasons of precision, speed and leakage radiation).
authors: Universität Würzburg, Klinik und Poliklinik für Strahlentherapie, Würzburg, Germany. Bratengeier_k@klinik.uni-wuerzburg.de
authors: Klaus
authors: K
authors: Bratengeier
authors: Matthias
authors: M
authors: Guckenberger
authors: Jürgen
authors: J
authors: Meyer
authors: Gerd
authors: G
authors: Müller
authors: Leo
authors: L
authors: Pfreundner
authors: Franz
authors: F
authors: Schwab
authors: Michael
authors: M
authors: Flentje
mesh_terms: D000465:Algorithms; D001943:Breast Neoplasms / Q000532:radiotherapy; D002648:Child; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013125:Spinal Neoplasms / Q000532:radiotherapy