Scintillation camera with improved resolution

Claim 2

Apparatus for imaging an object containing a radioactivity distribution comprising: a radiation detector of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output signals generally representing spatial coordinates of interaction of an associated quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said detector having a predetermined resolution value and having an inherent characteristic non-linear spatial response; radiation filter means interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; a documentation medium; signal filtering means receiving said pair of output signals operative to produce on said documentation medium a visual documentation at a position corresponding to coordinates of a central axis of one of said radiation passageways traversed by said associated quantum of radiation; and scanning means for producing relative scanning between said object and said radiation filter means and a synchronous relative scanning between said signal filtering means and said documentation medium; said signal filtering means comprising window circuit means defining a two parameter array of signal filter windows and a corresponding two parameter array of associated documentation positions, each of said signal filter windows being fitted to output signals associated with quanta of radiation traversing one of said radiation passageways to compensate for said nonlinear spatial response of said radiation imaging apparatus, and each of said documentation positions coinciding with the coordinates of a central axis of said associated radiation passageway; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus.

Claim 3

Apparatus for imaging an object containing a radioactivity distribution comprising: a radiation detector 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 respresenting spatial coordinates of interaction of a quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said detector having a predetermined resolution value and having an inherent characteristic non-linear spatial response; radiation filter means interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; signal filtering means receiving said pair of output electrical signals operative to produce a pair of filtered output signals representing position coordinates of a central axis of a particular one of said radiation passageways traversed by said quantum of radiation; documenting means receiving said pair of filtered output signals operative to document said signals in the form of a spatially located visible spot; and scanning means for producing relative scanning between said object and said radiation filter means and a synchronous relative scanning between said signal filtering means and said documenting means; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus; said signal filtering means comprising: means for digitizing each of said output electrical signals into one of a number of digital signal levels and producing a pair of digitized output signals, said number of digitized signal levels being at least several times greater than the greater number of radiation passageways along the axes of said rectangular coordinate system; and means for defining a unique two parameter set of digitized signal levels associated with each of said radiation passageways in accordance with said non-linear spatial response of said radiation imaging apparAtus and operative in response to a pair of digitized output signals associated with a particular two parameter set to produce said pair of filtered output signals.

Claim 4

Apparatus for imaging an object containing a radioactivity distribution comprising: a radiation detector 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 respresenting spatial coordinates of interaction of a quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said detector having a predetermined resolution value and having an inherent characteristic non-linear spatial response; radiation filter means interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; signal filtering means receiving said pair of output electrical signals operative to produce a pair of filtered output signals representing position coordinates of a central axis of a particular one of said radiation passageways traversed by said quantum of radiation; documenting means receiving said pair of filtered output signals operative to document said signals in the form of a spatially located visible spot; and scanning means for producing relative scanning between said object and said radiation filter means and a synchronous relative scanning between said signal filtering means and said documenting means; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus; said signal filtering means comprising: means for digitizing each of said output electrical signals into one of a number of digital signal levels and producing a pair of digitized output signals, said number of digitized signal levels being at least several times greater than the greater number of radiation passageways along the axes of said rectangular coordinate system; and means for defining a unique two parameter set of digitized signal levels associated with each of said radiation passageways in accordance with said non-linear spatial response of said radiation imaging apparAtus and operative in response to a pair of digitized output signals associated with a particular two parameter set to produce said pair of filtered output signals.

Claim 5

Apparatus as claimed in claim 2, wherein said means for digitizing comprises a pair of analog-to-digital converters each receiving one of said output electrical signals and producing a pair of digital words each comprising a particular channel address; and wherein said means for defining comprises: storage means for storing a set of pairs of channel addresses associated with each of said radiation passageways; and processor means receiving said pair of digital words and communicating with said storage means operative to determine a particular set associated with said pair of digital words and to produce said pair of filtered output signals representing the position coordinates of a central axis of a particular radiation passageway associated with said set; said storage of a set of pairs of channel addresses associated with each of said radiation passageways being based on measurements previously performed with said radiation imaging apparatus exposed through said radiation filter means to a substantially uniform radiation source, whereby each set of pairs of channel addresses is corrected for said characteristic non-linear spatial response of said radiation detector.

Claim 6

Apparatus for imaging an object containing a radioactivity distribution comprising a radiation detector of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output signals generally representing spatial coordinates of interaction of an associated quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said apparatus having a predetermined resolution value and having an inherent characteristic non-linear spatial response; a radiation filter interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; drive means for scanning said radiation filter stepwise in a rectilinear raster and producing a pair of filter position signals; a pair of analog-to-digital converters receiving said pair of output signals and producing a pair of digitized output signals; storage means for storing each said pair of digitized output signals as an accumulated event at an appropriate location in a two parameter array of storage elements; memory means for storing a set of window parameters each corresponding to one of said radiation passageways in at least one position of said radiation filter, said parameters being predetermined in accordance with said non-linear spatial response of said radiation imaging apparatus; a display means; processor means receiving said pair of filter position signals operative to accumulate events in said storage means within each of said stored window parameters and to display said accumulated events on said display means at a position corresponding to coordinates of central axes of associated radiation passageways; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus.

Claim 7

Apparatus for imaging an object containing a radioactivity distribution comprising a radiation detector of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output signals generally representing spatial coordinates of interaction of an associated quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said apparatus having a predetermined resolution value and having an inherent characteristic non-linear spatial response; a radiation filter interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; drive means for scanning said radiation filter stepwise in a rectilinear raster and producing a pair of filter position signals; a pair of analog-to-digital converters receiving said pair of output signals and producing a pair of digitized output signals; storage means for storing each said pair of digitized output signals as an accumulated event at an appropriate location in a two parameter array of storage elements; memory means for storing a set of window parameters each corresponding to one of said radiation passageways in at least one position of said radiation filter, said parameters being predetermined in accordance with said non-linear spatial response of said radiation imaging apparatus; a display means; processor means receiving said pair of filter position signals operative to accumulate events in said storage means within each of said stored window parameters and to display said accumulated events on said display means at a position corresponding to coordinates of central axes of associated radiation passageways; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus.

Claim 8

Apparatus for imaging an object containing a radioactivity distribution comprising: a radiation detector of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output signals generally representing spatial coordinates of interaction of an associated quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said apparatus having a predetermined resolution value and having an inherent characteristic non-linEar spatial response; a radiation filter interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; a pair of analog-to-digital converters receiving said pair of output signals and producing a pair of digitized output signals; storage means for storing each said pair of digitized output signals as an accumulated event at an appropriate location in a two parameter array of storage elements; memory means for storing a set of window parameters each corresponding to one of said radiation passageways, said parameters being predetermined in accordance with said non-linear spatial response of said radiation imaging apparatus; a display means; processor means for accumulating events in said storage means within each of said stored window parameters and displaying said accumulated events on said display means at positions corresponding to coordinates of central axes of associated radiation passageways; scanning means for scanning said object in relation to said radiation filter and synchronously scanning said display means; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus.

Claim 9

Apparatus for imaging an object containing a radioactivity distribution comprising: a radiation detector of the type which includes a radiation sensitive transducer and circuit means associated with said transducer for producing a pair of output signals generally representing spatial coordinates of interaction of an associated quantum of radiation with said transducer, said coordinates being related to a rectangular coordinate system associated with said transducer, said apparatus having a predetermined resolution value and having an inherent characteristic non-linEar spatial response; a radiation filter interposed between said transducer and said object for defining a two parameter array of mutually spaced radiation passageways to said transducer for radiation quanta emitted from said object; a pair of analog-to-digital converters receiving said pair of output signals and producing a pair of digitized output signals; storage means for storing each said pair of digitized output signals as an accumulated event at an appropriate location in a two parameter array of storage elements; memory means for storing a set of window parameters each corresponding to one of said radiation passageways, said parameters being predetermined in accordance with said non-linear spatial response of said radiation imaging apparatus; a display means; processor means for accumulating events in said storage means within each of said stored window parameters and displaying said accumulated events on said display means at positions corresponding to coordinates of central axes of associated radiation passageways; scanning means for scanning said object in relation to said radiation filter and synchronously scanning said display means; the size and separation distance of said radiation passageways being preselected in terms of said resolution value of said detector to produce a desired value of resolution of the overall apparatus.