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The importance of computed tomography slice thickness in radiographic patient positioning for radiosurgery
Author(s) -
Murphy Martin J.
Publication year - 1999
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598500
Subject(s) - radiography , radiosurgery , image guided radiation therapy , computed radiography , tomography , nuclear medicine , radiology , skull , medicine , image resolution , computed tomography , radiation therapy , computer science , image quality , computer vision , surgery , image (mathematics)
A new radiographic patient positioning technique developed for radiosurgery has been analyzed to show the effect of computed tomography (CT) slice thickness on the precision of target localization during treatment. The positioning technique establishes the pose of the patient's anatomy during treatment by comparing treatment room radiographs with digitally reconstructed radiographs derived from a CT study. The measured pose is then used to align the x‐ray therapy beam with the treatment site, without resorting to mechanical fixation. The technique has been found to be sensitive to submillimeter changes in skull position, which is the level of precision desired for radiosurgery. In this report it is shown that the precision of head localization improves by a factor of 2 when the CT slice thickness is reduced from 3.0 to 1.5 mm. This indicates that, in radiosurgical applications, image‐guided beam alignment can be significantly influenced by the spatial resolution of the reference CT study. This result is relevant to all high‐precision radiographic positioning techniques that utilize CT images.