Method and apparatus for measuring radiation in computer-assisted tomography and radiographic applications

Claim 2

Radiographic apparatus for determining the intensity of penetrating radiation passing through an object as a plurality of penetrating ray photons along a plurality of respective paths from a radiation source; comprising: (a) high-speed scintillator means having a very fast decay time for detecting the plurality of penetrating ray photons passing through the object along one of the plurality of paths and converting the energy of the penetrating ray photons into a plurality of light photons within a sufficiently short time interval after detection such that substantially all light photons associated with each detected penetrating ray photon are generated within different time intervals; (b) photomultiplier means optically coupled to said scintillator means for detecting the light photons associated with each penetrating ray photon detected and generating a signal for each plurality of light photons associated with a penetrating ray photon detected; and (c) counting means for counting the signals generated by said photomultiplier means and generating output signals representative of the number of penetrating ray photons detected.

Claim 3

The apparatus of claim 1 wherein: said scintillator means has a wall lining absorbent of penetrating ray photons so as to be self-collimating.

Claim 4

The apparatus of claim 2, wherein: (a) a portion of the penetrating ray photons transmitted from said radiation source is deflected by the object from its initial path to form secondary photons of penetrating radiation; (b) the photons transmitted through the object along the plurality of paths are primary photons; and (c) said scintillator means has a longitudinal axis and detects primary and secondary photons whose paths are within a small angular deviation from the longitudinal axis.

Claim 5

The apparatus of claim 3, wherein: (a) said photomultiplier means generates a primary signal for each primary photon detected and a secondary signal for each secondary photon detected; and (b) said counting means comprises: (1) discriminator means for discriminating between primary and secondary signals received from said photomultiplier means and generating event signals for each primary signal received; and (2) primary signal counter means for counting the number of event signals and generating output signals representative of the number of primary signals counted whereby the intensity of the penetrating radiation passing through the object along the path is determined.

Claim 8

Radiographic apparatus for determining the intensity of penetrating radiation passing through an object as a plurality of penetrating ray photons along a plurality of respective paths from a radiation source; comprising: scintillator means for detecting the plurality of penetrating ray photons passing through the object along one of the plurality of paths wherein said scintillator means has a wall lining absorbent of penetrating ray photons so as to be self-collimating.

Claim 9

Radiographic apparatus for determining the intensity of penetrating radiation passing through an object as a plurality of penetrating ray photons along a plurality of respective paths from a radiation source; comprising: scintillator means for detecting the plurality of penetrating ray photons passing through the object along one of the plurality of paths wherein said scintillator means has a wall lining absorbent of penetrating ray photons so as to be self-collimating.

Claim 10

The apparatus of claim 6, wherein said scintillator means comprises: (a) a scintillator of a suitable geometric configuration for collimating and detecting penetrating ray photons, said scintillator having an entry surface through which penetrating ray photons enter said scintillator, at least one lateral surface about said entry surface, and a longitudinal axis; (b) lining means disposed along said lateral surface for absorbing penetrating ray photons entering said scintillator whose paths are at a substantial angular deviation from a path parallel to said longitudinal axis and which are not detected prior to the time such photons reach said lateral surface.

Claim 11

The apparatus of claim 7, wherein: (a) said apparatus further comprises photomultiplier means optically coupled to said scintillator for detecting the light photons associated with each penetrating ray photon detected and generating a signal representative of the penetrating ray photons detected; and (b) said scintillator is configured to collimate and guide light photons.

Claim 12

The apparatus of claim 8, wherein said scintillator means further comprises: reflector means disposed between said lining means and said lateral surface of said scintillator for increasing the collimating efficiency of said scintillator means whereby the light photons generated by the detection of penetrating ray photons are collimated and efficiently guided a substantial distance to said photomultiplier means.

Claim 13

The apparatus of claim 7, further comprising: a second scintillator disposed adjacent the lining means of said first scintillator such that said lining means prevents penetrating ray photons which enter said first scintillator from interacting with said second scintillator.

Claim 14

The apparatus of claim 10, further comprising: (a) first photomultiplier means optically coupled to said first scintillator for detecting the light photons associated with each penetrating ray photon detected and generating a signal representative of the penetrating ray photons detected; (b) second photomultiplier means optically coupled to said second scintillator for detecting the light photons associated with each penetrating ray photon detected and generating a signal representative of the penetrating ray photons detected; and (c) wherein said adjacent first and second scintillators have different geometric configurations so that said photomultiplier means optically coupled to said scintillators are positioned in different planes, thereby allowing dense packing of said scintillator means regardless of the size of said photomultiplier means.

Claim 15

The apparatus of claim 7, wherein: said scintillator is composed of material suitable for producing sufficient travel distance between entry of penetrating ray photons and detection of said penetrating ray photons so that the photons entering said scintillator whose paths are at a substantial angular deviation from a path parallel to said longitudinal axis are absorbed by said lining means before detection.

Claim 16

The apparatus of claim 12, wherein said scintillator comprises: scintillating plastic.

Claim 17

The apparatus of claim 7, wherein: the width of said entry surface is sized so that substantially all of the penetrating ray photons detected pass through said entry surface and have paths within a small angular deviation from a path parallel to said longitudinal axis.

Claim 18

The apparatus of claim 14 wherein: the length of said scintillator is sufficiently long to allow photons which have paths within a smaller angular deviation from a path parallel to said longitudinal axis sufficient distance within said scintillator to be detected.

Claim 19

Apparatus for determining the intensity of penetrating ray photons passing through an object as a plurality of penetrating ray photons along a plurality of respective paths from a radiation source; comprising: (a) scintillator means for detecting the penetrating ray photons and converting energy from penetrating ray photons into light photons, said scintillator means comprising: (1) plastic scintillator of a suitable geometric configuration having an entry surface through which penetrating ray photons enter said scintillator, and at least one lateral surface about said entry surface which collimates both the penetrating ray photons and the light photons and which guide the light photons; wherein (i) said scintillator having a longitudinal axis; (ii) the width of said entry surface is sized so that substantially all of the penetrating ray photons detected pass through said entry surface and have paths within a small angular deviation from a path parallel to said longitudinal axis; and (iii) the length of said scintillator is sufficiently long to allow photons which have paths within a small angular deviation from a path parallel to said longitudinal axis a sufficient travel distance within said scintillator to be detected; (2) lining means disposed along said lateral surface for absorbing penetrating ray photons entering said scintillator whose paths are at a substantial angular deviation from a path parallel to said longitudinal axis and which are not detected prior to the time such photons reach said lateral surface; (3) reflector means disposed between said lining means and said lateral surface for increasing the collimating efficiency and guiding efficiency of said scintillator means for light photons; and (b) means optically coupled to said scintillator means for detecting the light photons and generating a signal representative of the penetrating ray detected.

Claim 20

Apparatus for determining the intensity of penetrating ray photons passing through an object as a plurality of penetrating ray photons along a plurality of respective paths from a radiation source; comprising: (a) scintillator means for detecting the penetrating ray photons and converting energy from penetrating ray photons into light photons, said scintillator means comprising: (1) plastic scintillator of a suitable geometric configuration having an entry surface through which penetrating ray photons enter said scintillator, and at least one lateral surface about said entry surface which collimates both the penetrating ray photons and the light photons and which guide the light photons; wherein (i) said scintillator having a longitudinal axis; (ii) the width of said entry surface is sized so that substantially all of the penetrating ray photons detected pass through said entry surface and have paths within a small angular deviation from a path parallel to said longitudinal axis; and (iii) the length of said scintillator is sufficiently long to allow photons which have paths within a small angular deviation from a path parallel to said longitudinal axis a sufficient travel distance within said scintillator to be detected; (2) lining means disposed along said lateral surface for absorbing penetrating ray photons entering said scintillator whose paths are at a substantial angular deviation from a path parallel to said longitudinal axis and which are not detected prior to the time such photons reach said lateral surface; (3) reflector means disposed between said lining means and said lateral surface for increasing the collimating efficiency and guiding efficiency of said scintillator means for light photons; and (b) means optically coupled to said scintillator means for detecting the light photons and generating a signal representative of the penetrating ray detected.