Radiant energy – With infrared or thermal pattern recording – Thermal copying of documents
Patent
1972-02-09
1976-11-09
Lawrence, James W.
Radiant energy
With infrared or thermal pattern recording
Thermal copying of documents
250313, G03B 4116
Patent
active
039913104
ABSTRACT:
The center of tissue within a patient to be subjected to radiation treatment is located in terms of coordinates with respect to a predetermined origin defined by three mutually orthogonal reference axes. Projections of at least one of the axes are superimposed upon two radiographs in different radiographic planes showing the tissue center and surrounding features in enlarged dimensions. In order to determine the reduced, true coordinates of the tissue center in cases where frontal and lateral radiographs are obtained, one method is disclosed in which analytic geometry is applied to reduce the values of the projected coordinates. Reduction factors for the two radiographs are also ascertained so that the actual length, width and breadth of the treatment volume may be calculated. Alternatively, a localizer may be employed which positions the radiographs, or slides made therefrom, in orthogonal planes and illuminates the radiographs or slides with point light sources arranged to duplicate the geometry of the X-ray unit utilized in obtaining the radiographs. A transparency having graduated axes thereon is interposed between the light sources and the radiographs or slides and positioned such that projections of the origin of the graduated axes are aligned with the tissue centers on both of the radiographs, permitting the true coordinates and the dimensions of the treatment volume to be directly read from the graduations on the projected axes. A third technique is disclosed in which the true coordinates are determined irrespective of the angular locations of the X-ray focuses, and employs a two-dimensional simulation of the radiographic geometry upon which transverse coordinates from the radiographs are plotted using assumed focus-to-center distances and then translated graphically to find the true coordinates.
REFERENCES:
patent: 2650308 (1953-08-01), Catlin
patent: 2770719 (1956-11-01), Simjian
patent: 3082322 (1963-03-01), Koerner
patent: 3673394 (1972-06-01), Hartmann
Church C. E.
Lawrence James W.
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