Apparatus for examining a body by radiation such as X or gamma radiation

A method comprising the steps of:

• irradiating a sectional slice of a body with x-rays;
• receiving the x-rays emerging from the slice during each of a succession of detector sampling time intervals and generating, in response, first electrical signals each of which is a function of the x-rays which have travelled through the slice within a respective path during a respective detector sampling time interval, each respective one of said paths having a geometric center line which is straight, where the paths having center lines which are not separated from each other by another center line of a path overlap each other throughout the slice, and where said center lines are distributed at least throughout an angle of about 180.degree. relative to the slice, and every elemental part of the slice is intersected by a number of said paths;
• deriving, from said first electrical signals, second electrical signals which have a positional correspondence to said center lines, where each second electrical signal is a function of a number of said first electrical signals;
• building up an x-ray picture of the slice by accumulating, for each given elemental area of the picture, allocations which are functions of the second electrical signal which have a positional correspondence with first electrical signals which are functions of the x-rays that have travelled along beam paths intersecting the elemental part of the slice pictured at said given elemental area of the picture, and forming a visual representation of said x-ray picture.

A method comprising the steps of:

• irradiating a sectional slice of an object with x-rays coming from an x-ray origin moving relative to the slice;
• receiving x-rays emerging from the slice and generating, in response, first electrical signals where:
• (i) each respective first electrical signal is generated in response to the x-rays received by a respective detector device during a respective detector sampling time interval;
• (ii) the x-ray origin and each respective detector device occupy respective positions during each respective detector sampling time interval, and all of the x-rays which go directly from the x-ray origin to a respective detector device during a detector sampling time interval travel within a beam path bound at its longitudinal ends by the outlines of the last recited respective positions of the x-ray origin and detector device;
• and
• (iii) any two beam paths, whether or not they exist at the same time, which are not separated from each other by another beam path spatially overlap with each other throughout the slice;
• converting said first electrical signals to second electrical signals, where each second electrical signal is a function of a respective multiplicity of the first electrical signals, and each second electrical signal is associated with a respective direction across the slice, said directions being distributed at least through an angle of about 180.degree. relative to the slice;
• converting the second electrical signals into third electrical signals, where each third electrical signal is associated with a respective small area of an x-ray picture of the slice and is a function of those second electrical signals which are associated with directions passing through the part of the slice pictured at said small area of the picture;
• and
• converting said third electrical signals into a visible x-ray picture of the slice.

A medical diagnostic method of examining a patient and building up and displaying a two-dimensional picture of the x-ray absorption of the elements into which a substantially planar slice of the patient is divided by a finite Cartesian notional matrix superimposed on the slice, comprising:

• producing x-radiation originating at an origin scanning around the patient, said x-radiation passing through the patient while the origin scans at least half way around the patient, and detecting the x-radiation and producing electrical signals corresponding to the absorption suffered by the x-radiation in passing through the patient along beam paths which are in or substantially in the slice, at least some of these beam paths intersecting each other and the neighboring beam paths overlapping each other;
• providing signal receiving meshes corresponding to the slice elements and allocating, for each given beam path, to the meshes corresponding to the slice elements through which the given beam path passes, allocations determined by a correction signal weighted in accordance with the relative disposition of the given beam path and the slice elements through which the given beam path passes, said correction signal being determined by modifying the electrical signal corresponding to the given beam path in accordance with other electrical signals, corresponding to beam paths which pass through slice elements other than those through which the given beam path passes, and accumulating said allocations to each signal receiving mesh to thereby build up said picture;
• and
• displaying the so accumulated allocations to the signal receiving meshes to thereby display said two-dimensional picture of the x-ray absorption of the elements of the patient slice.

A medical diagnostic method of examining a patient and building up and displaying a two-dimensional picture of the x-ray absorption of the elements into which a planar or a substantially planar slice of the patient is divided by a finite Cartesian matrix notionally superimposed on the slice, comprising:

• producing x-radiation originating at an origin scanning around the patient, said radiation passing through the patient while the origin scans at least half way around the patient, and detecting the x-radiation and producing electrical signals corresponding to the absorption suffered by the x-radiation in passing through the patient along beam paths at least some of which intersect each other, with neighboring beam paths overlapping each other;
• providing signal receiving meshes corresponding to the slice elements and making a succession of signal allocations to each mesh to thereby build up said picture of the x-ray absorption of the slice elements, each signal allocation to any one mesh being responsive to the electrical signal corresponding to a beam path passing through the slice element which corresponds to that mesh modified by electrical signals corresponding to beam paths not passing through that slice element, a so modified electrical signal being derived for each individual one of said electrical signals and being allocated to all of the meshes corresponding to slice elements through which the beam path corresponding to the individual electrical signal passes, in weights determined by the relative disposition of the last recited beam path and slice elements, each so modified and weighted signal constituting a signal allocation to a mesh, and the signal allocations to a mesh being accumulated thereby to thereby build up said picture;
• and
• displaying said accumulations of signal allocations to thereby display said two-dimensional picture of the x-ray absorption of the patient slice.

A method of examining a patient comprising:

• irradiating an area which includes a transverse slice of the patient with penetrating radiation propagating along many different but substantially coplanar directions distributed throughout the area and generating respective signals related to the radiation detected after leaving said area along the respective directions;
• using said signals to build up a picture of the slice by an apparatus-implemented process in which (i) each of substantially all of said signals contributes to substantially the entire picture and (ii) substantially the entire picture receives contributions from one group of said signals and then from another as it is being built up;
• wherein each group of signals is related to a group of directions distributed substantially uniformly through substantially the entire slice, and wherein said picture has a contrast range corresponding to the range at least from soft tissue through bone;
• and
• displaying a visual representation of said picture which selectively shows only a portion of said contrast range within a selectable window width at a selectable window position.

A method of examining a patient comprising:

• irradiating an area which includes a transverse slice of the patient with penetrating radiation propagating along many different but substantially coplanar directions distributed throughout the area, and generating respective signals related to the radiation detected after leaving said area along the respective directions;
• subjecting said signals to an apparatus-implemented process to build up a picture of the slice by a sequence of steps in which (i) each of substantially all of said signals contributes to substantially the entire picture and (ii) substantially the entire picture receives contributions based on one group of said signals and then receives and accumulates successive contributions based on successive other groups of said signals as it is being built up;
• and
• producing and displaying a tangible visible representation of at least a portion of said picture.