A comparison between 2-Step IMRT and conventional IMRT planning.
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).
Bratengeier
Klaus
K
Universität Würzburg, Klinik und Poliklinik für Strahlentherapie, Würzburg, Germany. Bratengeier_k@klinik.uni-wuerzburg.de
Guckenberger
Matthias
M
Meyer
Jürgen
J
Müller
Gerd
G
Pfreundner
Leo
L
Schwab
Franz
F
Flentje
Michael
M
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