Apparatus and methods for calculating gamma radiography variables
OwnerPaul T. Hayesinventor
Life of this patent
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Abstract
An apparatus and method for calculating gamma radiography variables is provided. The apparatus includes a base with a circular logarithmic time scale displayed thereon, a first disk concentric and rotatably coupled to said base for displaying a circular logarithmic radiation source scale and a circular logarithmic source-to-film distance scale, a second disk displaying a circular nearly linear steel thickness scale and a radial tick mark F, and a third disk displaying a radial baseline mark and a plurality of film type marks. The method disclosed allows calculation of exposure time from known quantities: film type, source-to-film distance, steel thickness, radiation source type and strength.
Claims16
A calculator for solving gamma radiography variables comprising:
- a base for displaying a time scale;
- a first disk rotatably coupled to said base for displaying a radiation source strength scale opposed to said time scale and for displaying a source-to-film distance scale;
- a second disk rotatably coupled to said base and said first disk for displaying a thickness scale opposed to said source-to-film distance scale and for displaying a radial F mark;
- and
- a third disk rotatably coupled to said base, said first disk and said second disk for displaying a film type scale opposed to said radial F mark and for displaying a radial baseline mark.
A circular calculator for solving gamma radiography variables comprising:
- a base for displaying a logarithmic time scale outside a circle of radius R.sub.1, wherein said logarithmic time scale begins at a zero reference point;
- a first disk of radius R.sub.1 adjacent to, and rotatably coupled to, said base and concentric with said circular logarithmic time scale for displaying a circular logarithmic radiation source strength scale and for displaying a circular logarithmic source-to-film distance scale;
- a second disk of radius R.sub.2 adjacent and concentric to said first disk and rotatably coupled to both said first disk and said base for displaying a circular thickness scale and for displaying a radial tick mark F, wherein R.sub.2 <R.sub.1 ;
- and
- a third disk of radius R.sub.3 adjacent and concentric to said second disk and rotatably coupled to said base, said second disk and said first disk for displaying a radial baseline mark and for displaying a plurality of film type marks, wherein R.sub.3 <R.sub.2.
A coplanar circular calculator for solving gamma radiography variables comprising:
- a base for displaying a logarithmic time scale outside a circle of radius R.sub.1, wherein said logarithmic time scale begins at a zero reference point;
- a first annular ring of outer radius R.sub.1, and inner radius R.sub.2, coplanar with, and rotatably coupled to, said base and concentric with said logarithmic time scale for displaying a circular logarithmic radiation source strength scale and for displaying a circular logarithmic source-to-film distance scale;
- a second annular ring of outside radius R.sub.2, and inside radius R.sub.3, coplanar with, concentric to, and rotatably coupled to, said first disk for displaying a circular thickness scale and for displaying a radial tick mark F;
- and
- a third disk of radius R.sub.3, coplanar with, concentric to, and rotatably coupled to said second disk for displaying a radial baseline mark and for displaying a plurality of film type marks.
A method of calculating exposure time for gamma radiography using an apparatus for calculating gamma radiography variables given film type, source-to-film distance, object thickness, and radiation source strength comprising:
- providing an apparatus for calculating gamma radiography variables including a base, a first disk, a second disk and a third disk;
- selecting a film type corresponding to film being used from a plurality of film types radially marked along a circumference of said third disk on said apparatus;
- rotating said second disk until a radial tick mark F on said second disk lines up with said selected film type mark;
- rotating said first disk until a source-to-film distance marked on said first disk corresponding to distance between a radiation source and film for said radiograph lines up with object thickness of subject radiograph as marked on said second disk;
- and
- reading exposure time displayed on base of said apparatus corresponding to radiation source strength of said radiation source as displayed on said first disk.
A method of adjusting calculation of exposure time for gamma radiography using an apparatus for calculating gamma radiography variables to obtain density between 2.75 and 3.0 comprising:
- providing an apparatus for calculating gamma radiography variables including a base, a first disk, a second disk, a third disk and radiographic film placed for exposure;
- setting a radial baseline mark on said third disk to a zero reference point;
- selecting a film type corresponding to said radiographic film from a plurality of film types radially marked along a circumference of said third disk of said apparatus;
- rotating said second disk until a radial tick mark F lines up with said selected film type mark;
- rotating said first disk until a source-to-film distance corresponding to distance between a radiation source and said radiographic film marked on said first disk lines up with object thickness of subject radiograph;
- selecting calculated exposure time displayed on base of said apparatus corresponding to radiation source strength of said radiation source as displayed on said first disk;
- exposing said radiographic film based on calculated exposure time;
- developing a radiograph;
- determining density of said developed radiograph;
- adjusting said radial baseline mark clockwise up to 45.degree. relative to said zero reference point to increase density if determined density is below a range of 2.75 to 3.0;
- adjusting said radial baseline mark counterclockwise up to -15.degree. relative to said zero reference point to decrease radiograph density if determined density is above said range of 2.75 to 3.0;
- and
- repeating above steps as necessary to obtain a radiograph of density 2.75 to 3.0.
Dependencies are inferred from the claim text.