Radiation imaging system with cyclically shiftable grid assembly
First Claim
1. A method for producing a transparency image of an object subjected to penetrative radiation comprising:
- (a) positioning a generally planar image forming element at a predetermined position relative to a source of penetrative radiation;
(b) stationing a grid assembly at an exposure position between the radiation source and the image forming element;
(c) directing penetrative radiation to said image forming element for a predetermined time; and
,(d) oscillating the grid assembly in a direction generally parallel to said plane at a first relatively constant frequency and altering the extent of grid assembly displacement from said exposure position during successive oscillations by cyclically shifting said grid assembly at a second substantially lower relatively constant frequency so that the grid assembly displacement in one direction of motion from the exposure position is not duplicated for a period which is relatively large compared to said time.
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Accused Products
Abstract
An X-ray spot filmer is disclosed including a system for cyclically shifting a grid assembly interposed between an X-ray source and a film cassette. The system comprises an electrically energizable grid assembly actuator and an actuator controller for energizing the actuator to cyclically shift the grid assembly. The actuator controller includes actuator energizing output circuitry effective to govern the direction and speed of operation of the actuator in response to a control signal and control signal generator circuitry for producing control signals effective to govern operation of the output circuitry including an oscillator for producing a cyclically varying control signal which causes cyclic grid assembly shifting.
34 Citations
13 Claims
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1. A method for producing a transparency image of an object subjected to penetrative radiation comprising:
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(a) positioning a generally planar image forming element at a predetermined position relative to a source of penetrative radiation; (b) stationing a grid assembly at an exposure position between the radiation source and the image forming element; (c) directing penetrative radiation to said image forming element for a predetermined time; and
,(d) oscillating the grid assembly in a direction generally parallel to said plane at a first relatively constant frequency and altering the extent of grid assembly displacement from said exposure position during successive oscillations by cyclically shifting said grid assembly at a second substantially lower relatively constant frequency so that the grid assembly displacement in one direction of motion from the exposure position is not duplicated for a period which is relatively large compared to said time. - View Dependent Claims (2, 3)
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4. A method of shifting a grid while exposing a photographic film to penetrative radiation comprising:
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(a) interposing a grid assembly between a source of penetrative radiation and film; (b) oscillating the grid assembly in a plane generally parallel to the film at a relatively low frequency; and (c) vibrating the grid assembly at a substantially high frequency while oscillating the grid so that successive alternate reversals of grid assembly direction occur at different locations relative to the film. - View Dependent Claims (5, 6, 7, 8)
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9. An X-ray grid shifting arrangement comprising:
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(a) a grid assembly; and (b) a grid assembly actuator system for shifting the position of said grid assembly; (c) said actuator system comprising actuator means and actuator controller means, said actuator controller means comprising; (i) first signal producing means for producing a first actuator controlling signal whose value changes cyclically; and (ii) second signal producing means for producing a second actuator controlling signal whose value changes cyclically at a substantially different frequency from that of said first actuator controlling signal; (iii) said actuator controller means operating said actuator means to cyclically shift the position of said grid assembly as a function of said first and second signals. - View Dependent Claims (10, 11, 12, 13)
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Specification