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Proceedings Paper

Registration of portal images for online correction of positioning errors during radiation therapy of prostate cancer
Author(s): Julia Vlad; Sebastian Eulenstein; Waldemar Wlodarczyk; Peter Wust; Roland Felix
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Paper Abstract

Radiation therapy of prostate cancer requires a high geometric accuracy of dose delivery. Unfortunately, this accuracy can be hardly obtained because of imperfect patients repositioning throughout the preparation and execution of the treatment. In order to correct for such errors we developed methods for online registration of portal images (PI) and digitally reconstructed radiographs (DRR). To improve the preconditions for registration of the Pis and DRRs image preprocessing, such as contrast-limited adaptive histogram equalization (CLAHE) of the Pis, noise and edge filtering of the Pis and the DRRs, has been performed. Then, similarity measures as mean square error, cross correlation and mutual information were investigated. A fully automatic bony-based registration method has been developed. As a reference method a semi-automatic stereometric fiducial-based registration has also been developed. This method uses gold seeds implanted into the prostate as internal fiducial markers for assessment of the similarity measures. Small lead spheres as well were adhered as external fiducial markers on the Alderson phantom. This method was also used for the verification of the automatic bony-based registration. The registration of repositioning was then performed fully automatically in less than 30 s with the Alderson phantom and with the patient data. At the present stage, there remains a registration error of less than 2 mm.

Paper Details

Date Published: 28 May 2001
PDF: 8 pages
Proc. SPIE 4319, Medical Imaging 2001: Visualization, Display, and Image-Guided Procedures, (28 May 2001); doi: 10.1117/12.428102
Show Author Affiliations
Julia Vlad, Strahlenklinik Charite Campus Virchow Klinikum (Germany)
Sebastian Eulenstein, Strahlenklinik Charite Campus Virchow Klinikum (Germany)
Waldemar Wlodarczyk, Strahlenklinik Charite Campus Virchow Klinikum (Germany)
Peter Wust, Strahlenklinik Charite Campus Virchow Klinikum (Germany)
Roland Felix, Strahlenklinik Charite Campus Virchow Klinikum (Germany)

Published in SPIE Proceedings Vol. 4319:
Medical Imaging 2001: Visualization, Display, and Image-Guided Procedures
Seong Ki Mun, Editor(s)

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