Radiographic examination system

• US 4,599,740 A
• Filed: 09/03/1985
• Issued: 07/08/1986
• Est. Priority Date: 01/06/1983
• Status: Expired due to Fees

• Current Assignee: Arthur P. Cable
• Original Assignee: Arthur P. Cable
• Inventors: Cable, Arthur P.
• Primary Examiner(s): Church, Craig E.
• Application Number:
  US06/772,144
• Time in Patent Office: 308 Days
• Field of Search: 378/57, 378/58, 378/99, 358/111
• US Class Current: 378/57
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays

Abstract

A radiographic examination system for performing X-ray examination of large items such as International container units is formed as an installation comprising housings for one or a plurality of X-ray sources such as linear accelerators which in operation transmit a continuous beam of radiation across a conveyor along which the units to be inspected are displaced either continuously or incrementally. The radiation transmitted through a container is detected in a folded sensor screen or array extending on one side and over the position occupied by a container under inspection. The sensor screen or array produces optical signals which are converted into electrical signals by a photo-diode array or a camera system such as a television camera, and transmitted as pulse coded electrical signals by a coding transfer unit to display screens and signal recording equipment where an image of the transmitted information can be displayed and/or recorded for further use.

Claims

1. A radiographic examination system for examining the contents of container units, in which container units to be examined are positioned between a high energy radiation source and radiation detecting means, said examination system comprising:

a high energy radiation source of X-rays,

a collimator means for producing a substantially parallel sided beam of radiation from said X-rays for transmission through said container unit,

X-ray radiation detector means, said X-ray radiation detector means operating directly or indirectly to produce electrical signals from said transmitted radiation beam of X-rays detected thereby,

said X-ray radiation detector means including first and second linearly extending radiation sensitive means, said first radiation sensitive means lying in a first plane and at a first angle to the axis of said transmitted radiation beam of X-rays and said second radiation sensitive means lying in a second plane at a second angle to said axis of said transmitted radiation beam of X-rays,

a display means at a location remote from said radiation detection means.

means for transmitting said electrical signals from said X-ray radiation detector means to said display means, said display means incorporating electronic processor means and at least one screen for displaying said information signals from both said first and said second radiation sensitive means as a complete optical image for visual inspection, and

one of photographic recording apparatus and electronic apparatus for recording said information signals displayed on said screen.

2. The radiographic examination system of claim 1, wherein said first radiation sensitive means extends substantially vertically alongside the path to be followed by containers past said X-ray radiation source, and said second radiation sensitive means extends generally horizontally above said path of said containers past said X-ray source, said signal processor means operating to combine signals from said first and second radiation sensitive means whereby to generate a single composite image representative of the contents of a said container.

3. The radiographic examination system of claim 2, wherein said first and said second radiation sensitive means each comprise an array of photodiode sensor elements each said photodiode sensor element comprising a scintillator element sensitive to incident X-ray radiation and operative in response thereto to produce an optical output signal, and a photodiode sensitive to said optical output signal and operative in response thereto to produce an electrical signal representative thereof.

4. The radiographic examination system of claim 1, wherein there are provided a plurality of screens for displaying a composite image representing the contents of the whole container subject to examination.

5. The radiographic examination system of claim 1, wherein the said first and said second radiation sensitive means of said X-ray radiation detector means comprises first and second fluoroscopic screens producing optical images from the incident X-ray radiation, and said means for transmitting electrical information signals from said X-ray radiation detector means to said display means includes camera means operating to convert said optical signals into electrical signals, said camera means being positioned out of the penumbra of said X-ray radiation beam.

6. The radiographic examination system of claim 1, wherein there are provided means for modulating said electrical signals with a pulse code modulation to transmit said information from said X-ray radiation detector means to said display means where said display means convert said coded electrical signals into an optical display on a screen.

7. The radiographic examination system of claim 1, wherein there are further provided electromagnetic storage means for storing said electrical signals and electronic processor means for delivering said stored electrical signals to said display means under the control of selective control means.

8. The radiographic examination system of claim 1, wherein there are provided heavy duty transport conveyors for positioning said containers for investigation between said X-ray radiation source and said X-ray radiation detector means.

9. The radiographic examination system of claim 1, wherein said X-ray radiation detector means and said radiation source are movable over a limited range for fine positioning with respect to a container under investigation.

10. The radiographic examination system of claim 1, wherein there are provided a plurality of high energy radiation generators spaced along a path defined by conveyor means for said containers and a corresponding plurality of X-ray radiation detector means spaced along the said container path in alignment with a respective said high energy radiation source both longitudinally of and transversely of said path, each said radiation source including collimator means limiting the beam of X-ray radiation emitted by said source to a fan-shape beam having substantially parallel sides and a divergence angle less than that subtended by the whole of the container at the point of emission of each said X-ray radiation beam from each said high energy source.

11. The radiographic examination system of claim 1, wherein said means for transmitting said electrical information signals from said X-ray radiation detector means to said display means include analogue-to-digital converters operating to convert analogue input signals from said detectors to digital signals,

parallel-to-serial converters connected to the output of said analogue-to-digital converters for converting said digital signals arriving in parallel to a sequential series of said digital signals, and memory means storing all said digital signals from successive scans by said X-ray radiation detector means as said container moves therepast, whereby to generate, in successive instants of time, successive images on said screen representing said container in successive positions as it is moved past said X-ray radiation detector means.