X-ray scanner & detector signal processing system

• US 4,788,704 A
• Filed: 11/17/1987
• Issued: 11/29/1988
• Est. Priority Date: 03/04/1985
• Status: Expired due to Term

• Current Assignee: Heimann GmbH
• Original Assignee: Heimann GmbH
• Inventors: Koch, Cornelius, Donges, Gerhard
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Hynds, Joseph A.
• Application Number:
  US07/121,862
• Time in Patent Office: 378 Days
• Field of Search: 378/99, 378/57, 378/58, 378/100, 358/111, 358/106, 358/105, 358/167, 358/163, 250/359.1, 250/360.1, 364/574, 364/517
• US Class Current: 378/98.8
• CPC Class Codes: G01N 23/043 using fluoroscopic examination, with visual observation or video transmission of fluoroscopic images
• CPC Class Codes: G01V 5/20 Detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects
• CPC Class Codes: H05G 1/60 Circuit arrangements for obtaining a series of X-ray photographs or for X-ray cinematography

Abstract

An X-ray device for scanning objects moving on a conveyor path and for processing the detector signals acquired by the scan has a comparator for identifying faulty signals, the comparator being in a control chain for an image storage memory such that, in the event of a faulty detector signal, the contents of a memory row preceding the faulty detector signal are transferred into the memory row into which the faulty detector signal, if a correct signal, would have been stored. The system also includes a correction element for generating a reference signal at 100% radiation intensity in which the mean value of a number of measured signals is formed. The system also includes an element for reducing the amplitude of the useful signal during measurement in comparison to the amplitude allocated to a radiation intensity of 100%.

Claims

1. An x-ray device for scanning objects moving on a conveyor path and for processing signals for generating a visual display of said objects comprising:

means disposed on one side of said conveyor path for directing a fan-shaped x-ray beam at said objects perpendicular to the direction of conveyance of said objects;

an array of a plurality of x-ray detectors disposed on an opposite side of said conveyor path for detecting radiation passing through said objects;

an image memory connected to a display means for visually displaying said objects, said image memory having a plurality of memory cells corresponding in number to said plurality of detectors for storing a signal from each detector therein;

means for controlling entry of signals from said detectors into said memory;

means for measuring at least one selected type of error in a current detector signal; and

comparator means connected to said means for measuring for identifying the presence of an unacceptable error in a current detector signal, said comparator means being connected to said means for controlling entry of signals and supplying a signal thereto upon identification of an unacceptable error inhibiting transfer of said current detector signal into said image memory and instead transferring the contents of a selected memory cell preceding the cell allocated for said current detector signal to said cell allocated for said current signal in place of said current signal.

2. An x-ray device as claimed in claim 1, further comprising:

means for reducing the amplitude of said detector signal during measurement in comparision to an amplitude allocated to a radiation intensity of 100%.

3. An x-ray device as claimed in claim 2, further comprising means for forming a reference signal at 100% radiation intensity.

4. An x-ray device as claimed in claim 3, wherein said means for reducing the amplitude is a divider having an input connected to said detector array, an input connected to said means for generating said reference signal, and an output connected to said means for controlling entry of signals into said image memory.

5. An x-ray device as claimed in claim 4, wherein said means for forming a reference signal is an accumulator having an input connected to said output of said divider.

6. An x-ray device as claimed in claim 5, wherein said accumulator generates a reference signal R_i through n cycles according to the formula ##EQU2## wherein R_i is the measured value of the signal from each of said detectors.

7. An x-ray device for scanning objects moving on a conveyor path, processing signals acquired by said scanning, and displaying said signals on a display means, comprising:

means disposed on one side of said conveyor path for directing a fan-shaped x-ray beam at said objects perpendicular to the direction of conveyance of said objects;

an array of a plurality of x-ray detectors disposed on an opposite of said conveyor path for detecting radiation passing through said objects and for generating a signal corresponding to the detected radiation;

an image memory connected to a display, said image memory having a plurality of memory cells corresponding in number to said plurality of detectors for storing said signal from each detector therein;

means for controlling entry of signals from said detectors into said image memory;

divider means for forming a useful signal of reduced amplitude for each detector signal by dividing each detector signal by a reference signal for a radiation intensity of 100%;

means for generating said reference signal connected to said divider means;

means providing an input to said divider for measuring selected types of errors in said useful signal; and

comparator means connected to the output of said divider, said comparator means being connected to said means for controlling entry of signals into said image memory for inhibiting transfer of a current signal upon the identification of an unacceptable error in the output from said divider and instead transferring the contents of a selected memory cell preceding the cell allocated for said current signal to said cell allocated for said current signal in place of said current signal.