Document Detail


Electromagnetic real-time tumor position monitoring and dynamic multileaf collimator tracking using a Siemens 160 MLC: geometric and dosimetric accuracy of an integrated system.
MedLine Citation:
PMID:  20656420     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: Dynamic multileaf collimator tracking represents a promising method for high-precision radiotherapy to moving tumors. In the present study, we report on the integration of electromagnetic real-time tumor position monitoring into a multileaf collimator-based tracking system.
METHODS AND MATERIALS: The integrated system was characterized in terms of its geometric and radiologic accuracy. The former was assessed from portal images acquired during radiation delivery to a phantom in tracking mode. The tracking errors were calculated from the positions of the tracking field and of the phantom as extracted from the portal images. Radiologic accuracy was evaluated from film dosimetry performed for conformal and intensity-modulated radiotherapy applied to different phantoms moving on sinusoidal trajectories. A static radiation delivery to the nonmoving target served as a reference for the delivery to the moving phantom with and without tracking applied.
RESULTS: Submillimeter tracking accuracy was observed for two-dimensional target motion despite the relatively large system latency of 500 ms. Film dosimetry yielded almost complete recovery of a circular dose distribution with tracking in two dimensions applied: 2%/2 mm gamma-failure rates could be reduced from 59.7% to 3.3%. For single-beam intensity-modulated radiotherapy delivery, accuracy was limited by the finite leaf width. A 2%/2 mm gamma-failure rate of 15.6% remained with tracking applied.
CONCLUSION: The integrated system we have presented marks a major step toward the clinical implementation of high-precision dynamic multileaf collimator tracking. However, several challenges such as irregular motion traces or a thorough quality assurance still need to be addressed.
Authors:
Andreas Krauss; Simeon Nill; Martin Tacke; Uwe Oelfke
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-07-23
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  79     ISSN:  1879-355X     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-03     Completed Date:  2011-02-01     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  579-87     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Affiliation:
Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. andreas.krauss@dkfz-heidelberg.de
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MeSH Terms
Descriptor/Qualifier:
Electromagnetic Fields*
Electronics
Equipment Design
Fiducial Markers
Film Dosimetry / methods
Movement*
Particle Accelerators / instrumentation*
Phantoms, Imaging*
Radiotherapy, Conformal / instrumentation,  methods
Radiotherapy, Intensity-Modulated / instrumentation*,  methods

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