Quantifying the accuracy of affine transformations for modeling organ motion variabilities in external beam radiotherapy of prostate cancer Conference Paper


Authors: Fontenla, E.; Mageras, G.; Roeske, J. C.; Pelizzari, C. A.; Chen, G. T. Y.; Ling, C. C.
Editor: Enderle, J. D.
Title: Quantifying the accuracy of affine transformations for modeling organ motion variabilities in external beam radiotherapy of prostate cancer
Conference Title: 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Abstract: The present study is one part of an investigation of the hypothesis that a previously formulated statistical model [1] of organ motion can predict a more accurate distribution of dose to the target volume and normal tissues than would otherwise be calculated based only on the static anatomical information available in the planning CT scan. This study concerns utilizing affine transformations to model the day-to-day variability in the shape and size of the prostate, bladder, and rectum. Using data from a CT serial imaging study [3], the accuracy of this affine approximation was quantified for each organ by calculating the distance between corresponding points on the surface of the organ as delineated in the initial and subsequent CT scans, after the initial surface was transformed onto the subsequent scans using the affine transformation calculated for that organ motion. It was found that the distance between corresponding points on the two surfaces was less than 7.45 mm for 95% of the prostate points analyzed (average 2.7 mm), less than 10.6 mm for 95% of the bladder points analyzed (average 3.4 mm), and less than 14.5 mm for 95% of those rectum points for which this distance could be quantified (average 5.5 mm). However, on certain CT planes the rectum surfaces exhibited deviations that could not be properly quantified with the method utilized, and consequently the distance values for the rectum are not an accurate representation of the true accuracy of the affine transformation.
Keywords: radiotherapy; prostate cancer; prostate; computerized tomography; tumors; dosimetry; biological organs; tissue; rectum; bladder; organ motion; mathematical models; approximation theory; affine transformations
Journal Title IEEE Engineering in Medicine and Biology Society. Annual International Conference. Proceedings
Volume: 3
Conference Dates: 2000 Jul 23-28
Conference Location: Chicago, IL
ISBN: 1094-687X
Publisher: IEEE  
Location: Chicago, IL
Date Published: 2000-01-01
Start Page: 2149
End Page: 2152
Language: English
PROVIDER: scopus
DOI: 10.1109/IEMBS.2000.900555
DOI/URL:
Notes: Annu Int Conf IEEE Eng Med Biol Proc -- Conference code: 58180 -- Export Date: 18 November 2015 -- CODEN: CEMBA -- 23 July 2000 through 28 July 2000 -- Source: Scopus
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  1. Gikas S Mageras
    277 Mageras
  2. C Clifton Ling
    331 Ling