Analysis of Errors in Three-Dimensional Reconstruction of Radium Implants from Stereo Radiographs

Fitzgerald, Lawrence T.; Mauderli, Walter

doi:10.1148/115.2.455

Cited by 12 publications

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“…Several authors have pointed out the inconsistencies associated with source localization from paired radiographs. [16][17][18] One of the more promising methods of resolving the resultant source localization errors is through the use of a third film. [19][20][21] We are currently implementing a three-film technique that will provide a better basis for comparison to the axial scan data than our current orthogonal film method.…”

Section: Discussionmentioning

confidence: 99%

Source localization from axial image sets by iterative relaxation of the nearest neighbor criterion

et al. 1999

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The use of axial image sets has become widely used to localize interstitial brachytherapy sources. One application of this method of localization is to perform post-implant dosimetry following transperineal interstitial permanent prostate brachytherapy (TIPPB) where the target structure and the source locations are displayed on the same image. The design of an appropriate scanning sequence often results in abutting slices of an intermediate slice width (3, 4, or 5 mm). Because a single source may be imaged on more than one slice, the resultant scans always show many more source locations than actual sources implanted. The physicist is then faced with the tedious task of determining which sources appear on more than one slice and deciding which source locations to eliminate from the data set. We have developed an algorithm, similar to one employed by Roy et al., which automates this process by relaxing the nearest neighbor criterion until the number of sources is reduced to either the number of sources implanted or the number counted on a projection radiograph. This paper details this algorithm and the results of its application to phantom studies, comparing to known source locations, as well as clinical studies, comparing to orthogonal film source localization, on a series of ten patients. Phantom studies demonstrate the superiority of the algorithm over orthogonal film reconstruction, locating 100% of the sources within 5 mm of the actual location as compared to 66% for the paired radiographs. The clinical study findings are commensurate with these results, with 72% of the sources on average located within 5 mm of the corresponding source in the other data set. The positive correlation of the quality of the orthogonal film reconstruction results with the quality of the coregistration results suggests that differences in registration between the two data sets may be due primarily to the uncertainties in the orthogonal film reconstruction.

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Section: Discussionmentioning

confidence: 99%

Source localization from axial image sets by iterative relaxation of the nearest neighbor criterion

et al. 1999

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“…(ii) To simplify seed matching, stereo views with less than 20" of radiographic source separation are generally used. The small parallax may lead to inaccurate seed locations in the direction toward the radiographic (x-ray) source positions (Hallert 1970, Fitzgerald andMauderli 1975).…”

Section: Introductionmentioning

confidence: 99%

Rapid, accurate, three-dimensional location of multiple seeds in implant radiotherapy treatment planning

1983

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The three-dimensional (3D) locations of the radioactive seeds in an interstitial implant can be obtained from stereo-shift or orthogonal radiographs. When an implant contains a large number of seeds, however, there are often ambiguities in identifying corresponding seed images on two radiographs. Our method achieves accurate spatial locations by using three radiographs whose x-ray source positions are (i) in a plane which does not intersect the implant and (ii) widely separated to achieve adequate parallax. All triangulation is done in an anatomical coordinate reference frame attached to the patient so that patient motion does not introduce errors. We achieve independent error-insensitive calibration of each radiograph, rapid and accurate data entry in the local coordinates of each radiograph, 3D seed location in the patient (anatomical) reference frame, and automatic verification of each calculation.

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“…Η ακρίβεια της μεθόδου των προβολικών εικόνων είναι γενικά καλύτερη από αυτή της στερεο-μετατόπισης 15 . Για τη δεύτερη τεχνική, μικρά σφάλματα στη μέτρηση των yσυντεταγμένων μπορούν να οδηγήσουν σε μεγάλα σφάλματα στις ζ-τιμές, ειδικά εάν η μετατόπιση αντιστοιχεί σε μικρό τόξο 16 " 18 . Παρ'όλα αυτά, οι τεχνικές στερεομετατόπισης είναι καταλληλότερες για περιπτώσεις όπου οι πηγές δεν μπορούν τόσο εύκολα να ταυτοποιηθούν σε δύο ορθογώνιες προβολές (π.χ.…”

Section: τεγνικές στερεο-υετατόττισηςunclassified

Τριδιαστατη Ανακατασκευη Εμφυτευματων Βραχυθεραπειας Απο Εικονες Υπολογιστικου Τομογραφου

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Analysis of Errors in Three-Dimensional Reconstruction of Radium Implants from Stereo Radiographs

Cited by 12 publications

References 0 publications

Source localization from axial image sets by iterative relaxation of the nearest neighbor criterion

Source localization from axial image sets by iterative relaxation of the nearest neighbor criterion

Rapid, accurate, three-dimensional location of multiple seeds in implant radiotherapy treatment planning

Τριδιαστατη Ανακατασκευη Εμφυτευματων Βραχυθεραπειας Απο Εικονες Υπολογιστικου Τομογραφου

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