Method and apparatus for the detection and imaging of heavy metals

Claim 1

A method of detecting in sequentially inspected objects a target article made of or containing an elemental or compounded target metal of the kind capable of producing with impinging X-radiation within the range of 60-160 KeV a detectable photoelectric interaction, characterized by providing a radiation generating assembly ( 1 ) comprising a 110-160 KV X-ray source ( 2 ) in association with collimating ( 3 ) and filtering ( 4 ) means, generating with such assembly a collimated X-ray beam consisting of repeating cycles comprising each one energy bin having a flux centred around the K-edge energy of the target metal and, if desired, comprising additional energy bins; placing at a distance from the X-ray source and in a region flushed by said collimated X-ray beam a linear array ( 6 ) of solid state, spectroscopy grade detectors in association with signal counting, processing and imaging means; providing object carrier means ( 7 ) intermediary between said X-ray source and linear array of solid state, spectroscopy grade detectors; placing objects ( 8 ) on said carrier means; arranging for said X-ray source and collimated X-­ray beam on the one hand and said support means on the other hand to move relative to each other at a speed so selected that during each one of predetermined pixels the full energy range of one of said repeating cycles impinges a full cross-section of an inspected object without any mutual dislocation of said X-ray source ( 2 ) and linear array ( 6 ) of solid state detectors; recording for each pixel the intensity of transmitted radiation of selected energy bands; determining for each pixel the ratios between the transmitted radiation in said selected energy bands; and processing the resulting data to produce an image of any detected target article.

Claim 2

A method of detecting in sequentially inspected objects a target article made of or containing an elemental or compounded target metal of the kind capable of producing with impinging X-radiation within the range of 60-160 KeV a detectable photoelectric interaction, characterized by providing a radiation generating assembly ( 1 ) comprising a 110-160 KV X-ray source ( 2 ) in association with collimating ( 3 ) and filtering ( 4 ) means, generating with such assembly a collimated X-ray beam consisting of repeating cycles comprising each one energy bin having a flux centred around the K-edge energy of the target metal and, if desired, comprising additional energy bins; placing at a distance from the X-ray source and in a region flushed by said collimated X-ray beam a linear array ( 6 ) of solid state, spectroscopy grade detectors in association with signal counting, processing and imaging means; providing object carrier means ( 7 ) intermediary between said X-ray source and linear array of solid state, spectroscopy grade detectors; placing objects ( 8 ) on said carrier means; arranging for said X-ray source and collimated X-­ray beam on the one hand and said support means on the other hand to move relative to each other at a speed so selected that during each one of predetermined pixels the full energy range of one of said repeating cycles impinges a full cross-section of an inspected object without any mutual dislocation of said X-ray source ( 2 ) and linear array ( 6 ) of solid state detectors; recording for each pixel the intensity of transmitted radiation of selected energy bands; determining for each pixel the ratios between the transmitted radiation in said selected energy bands; and processing the resulting data to produce an image of any detected target article.

Claim 5

A method according to any one of Claims 1 to 3, characterized in that the relative movement of the object carrier means ( 7 ) and radiation generating assembly ( 1 ) is continuous.

Claim 6

A method according to any one of Claims 1 to 3, characterized in that the relative movement of the object carrier means ( 7 ) and radiation generating assembly ( 1 ) is intermittent.

Claim 7

A method according to any one of claims 1 to 5, characterized in that the filtering means ( 4 ) of said radiation generating assembly are designed to generate successively several energy bins during each of the said cycles, which is centred around the K-edge energy of the target metal.

Claim 8

A method according to any one of claims 1 to 6, characterized in that the filtering means ( 4 ) of said radiation generating assembly are designed to generate during each of the said cycles one single, preferably narrow energy bin only centred around the K-edge energy of the target metal, and the detectors ( 6 ) are arranged in such a way as to differentiate between simultaneous different radiation flux attenuations within predetermined energy ranges of said single energy bin.

Claim 9

An apparatus for the performance of the method according to any one of claims 1 to 7, characterized by a radiation generating assembly ( 1 ) comprising a 60-160 KeV X-ray source ( 2 ) in association with collimating ( 3 ) and filtering ( 4 ) means capable of generating a collimated X-ray beam consisting of repeating cycles comprising each one energy bin having a flux centred around the K-edge energy of the target metal and, if desired, additional energy bins; a linear array ( 6 ) of solid state, spectroscopy grade detectors in association with signal counting, processing and imaging means, which detectors are spaced from said radiation generating assembly; object carrier means ( 7 ) intermediary said radiation generating means and said linear array ( 6 ) of solid state, spectroscopy grade detectors; and means for causing the radiation generating means ( 1 ) and linear array ( 6 ) of solid state detectors, on the one hand and said object carrier means ( 7 ) on the other hand to move relative to each other at a speed so selected that during each of predetermined pixels the full energy band of one of said repeating cycles impinges a full cross-section of said object carrier means without any mutual dislocation between the radiation generating means and solid state detector array.

Claim 12

An apparatus according to any one of claims 8 to 10, characterized in that said means for causing the radiation generating means ( 1 ) and linear array ( 6 ) of solid state detectors on the one hand and said object carrier means ( 7 ) on the other hand to move relative to each other are adapted to produce an intermittent movement.

Claim 13

An apparatus according to any one of claims 8 to 12, characterized in that said radiation generating means ( 1 ) are adapted to produce repeating cycles each holding several energy bins.

Claim 14

An apparatus according to any one of claims 8 to 12, characterized in that said radiation generating means ( 1 ) are adapted to produce repeating cycles each holding a single energy bin and the detectors ( 6 ) and associated signal counting means are arranged in such a way as to differentiate between simultaneous different radiation flux attentuations within predetermined energy ranges of the said single energy bin.