Radiation imaging device

Claim 2

In combination: radiation imaging apparatus of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output electrical signals generally representing spatial coordinates of interaction of a quantum of radiation with said transducer, said apparatus having an inherent characteristic non-linear response such that a map of a uniform distribution of quanta of radiation interacting with said transducer produced by displaying a spot spatially located in accordance with said pair of electrical signals for each of said interacting quanta is distorted into a characteristic non-uniform distribution of spots; means for irradiating said transducer at discrete points defining an array; means for measuring and storing the magnitudes of said nonlinear response at said discrete points; and means receiving said output electrical signals operative to product a map of a distribution of quanta of radiation from an object viewed by said apparatus corrected in accordance with said stored magnitudes of non-linear response.

Claim 3

The combination as claimed in claim 1, wherein said radiation sensitive transducer comprises a scintillation crystal in the form of a round disc having about one-half inch thickness; and said circuit means comprises a plurality of photomultiplier tubes mounted in an array with a photosensitive face of each tube spaced from a top surface of said disc by about one-half inch, and circuitry receiving outputs from said tubes operative to produce said pair of electrical signals; whereby said radiation imaging apparatus is characterized by resolution improved from similar apparatus having a greater spacing between phototubes and crystal and the greater non-linear response of said circuit means is effectively reduced in said corrected map.

Claim 4

In combination: radiation imaging apparatus of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output electrical signals generally representing spatial coordinates of interaction of a quantum of radiation with said transducer; analog-to-digital conversion means for converting said pair of output electrical signals to a corresponding pair of binary digital words; storage means for storing said pair of digital words as a registered count in a rectangular matrix of storage elements, a map of a spatial distribution of quanta of radiation interacting with said transducer being produced by accumulating counts in said matrix, said map being distorted from the actual distribution by non-linearities inherent in said radiation imaging apparatus; correction factor storage means for storing pairs of coordinate correction factors associated with a regular array of points on said transducer; said coordinate correction factors being predetermined in accordance with measurements of the magnitude of non-linear response of said radiation imaging apparatus at said points; matrix correction means for correcting said map stored in said storage means in accordance with said coordinate correction factors to produce a map more accurately representing the actual spatial distribution of said quanta of radiation interacting with said transducer.

Claim 5

In combination: radiation imaging apparatus of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output electrical signals generally representing spatial coordinates of interaction of a quantum of radiation with said transducer; analog-to-digital conversion means for converting said pair of output electrical signals to a corresponding pair of binary digital words; storage means for storing said pair of digital words as a registered count in a rectangular matrix of storage elements, a map of a spatial distribution of quanta of radiation interacting with said transducer being produced by accumulating counts in said matrix, said map being distorted from the actual distribution by non-linearities inherent in said radiation imaging apparatus; correction factor storage means for storing pairs of coordinate correction factors associated with a regular array of points on said transducer; said coordinate correction factors being predetermined in accordance with measurements of the magnitude of non-linear response of said radiation imaging apparatus at said points; matrix correction means for correcting said map stored in said storage means in accordance with said coordinate correction factors to produce a map more accurately representing the actual spatial distribution of said quanta of radiation interacting with said transducer.

Claim 6

The combination as claimed in claim 3, wherein said radiation sensitive transducer comprises a scintillation crystal in the form of a round disc having about one-half inch thickness; and said circuit means comprises a plurality of photomultiplier tubes mounted in an array with a photosensitive face of each tube spaced from a top surface of said disc by about one-half inch, and circuitry receiving outputs from said tubes operative to produce said pair of electrical signals; whereby said radiation imaging apparatus is characterized by resolution improved from similar apparatus having a greater spacing between tubes and crystal and the greater non-linear response of said circuit means is effectively reduced in said corrected map.

Claim 7

In combination: radiation imaging apparatus of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output electrical signals generally representing spatial coordinates of interaction of a quantum of radiation with said transducer; correction factor storage means for storing pairs of coordinate correction factors associated with a regular array of points on said transducer; said coordinate correctioN factors being predetermined in accordance with measurements of the magnitude of non-linear response of said radiation imaging apparatus at said points; analog-to-digital conversion means for converting said pair of output electrical signals to a corresponding pair of binary digital words; correction means for producing a corrected version of said pair of binary digital words in accordance with an associated pair of coordinate correction factors; and accumulating means receiving corrected versions of pairs of binary digital words resulting from a spatial distribution of quanta of radiation interacting with said transducer operative to produce a map of said spatial distribution substantially undistorted by the non-linear response of said radiation imaging apparatus.

Claim 8

In combination: radiation imaging apparatus of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output electrical signals generally representing spatial coordinates of interaction of a quantum of radiation with said transducer; correction factor storage means for storing pairs of coordinate correction factors associated with a regular array of points on said transducer; said coordinate correctioN factors being predetermined in accordance with measurements of the magnitude of non-linear response of said radiation imaging apparatus at said points; analog-to-digital conversion means for converting said pair of output electrical signals to a corresponding pair of binary digital words; correction means for producing a corrected version of said pair of binary digital words in accordance with an associated pair of coordinate correction factors; and accumulating means receiving corrected versions of pairs of binary digital words resulting from a spatial distribution of quanta of radiation interacting with said transducer operative to produce a map of said spatial distribution substantially undistorted by the non-linear response of said radiation imaging apparatus.