Document Detail

Operator-free, film-based 3D seed reconstruction in brachytherapy.
MedLine Citation:
PMID:  12118599     Owner:  NLM     Status:  MEDLINE    
In brachytherapy implants, the accuracy of dose calculation depends on the ability to localize radioactive sources correctly. If performed manually using planar images, this is a time-consuming and often error-prone process-primarily because each seed must be identified on (at least) two films. In principle, three films should allow automatic seed identification and position reconstruction; however, practical implementation of the numerous algorithms proposed so far appears to have only limited reliability. The motivation behind this work is to create a fast and reliable system for real-time implant evaluation using digital planar images obtained from radiotherapy simulators, or mobile x-ray/fluoroscopy systems. We have developed algorithms and code for 3D seed coordinate reconstruction. The input consists of projections of seed positions in each of three isocentric images taken at arbitrary angles. The method proposed here consists of a set of heuristic rules (in a sense, a learning algorithm) that attempts to minimize seed misclassifications. In the clinic, this means that the system must be impervious to errors resulting from patient motion as well as from finite tolerances accepted in equipment settings. The software program was tested with simulated data, a pelvic phantom and patient data. One hundred and twenty permanent prostate implants were examined (105 125I and 15 103Pd) with the number of seeds ranging from 35 to 138 (average 79). The mean distance between actual and reconstructed seed positions is in the range 0.03-0.11 cm. On a Pentium III computer at 600 MHz the reconstruction process takes 10-30 s. The total number of seeds is independently validated. The process is robust and able to account for errors introduced in the clinic.
D A Todor; G N Cohen; H I Amols; M Zaider
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Physics in medicine and biology     Volume:  47     ISSN:  0031-9155     ISO Abbreviation:  Phys Med Biol     Publication Date:  2002 Jun 
Date Detail:
Created Date:  2002-07-16     Completed Date:  2003-01-07     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2031-48     Citation Subset:  IM    
Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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MeSH Terms
Brachytherapy / instrumentation*,  methods*
Models, Statistical
Phantoms, Imaging
Prostatic Neoplasms / radiotherapy
Radiometry / methods
Radiotherapy Planning, Computer-Assisted

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