Abstract: A method for examination of a subject comprises the steps of: administering (32) a contrast-enhancing agent into a subject (7, 42) to be examined, the contrast-enhancing agent introducing density variations in the subject; directing (33) ionizing radiation (3) towards the subject; and detecting (34) ionizing radiation spatially resolved as transmitted through the subject, while Compton scattered radiation (3a, 3c) in the subject is essentially prevented from being detected. The ionizing radiation directed towards the subject is provided within a spectral range so that more photons of the ionizing radiation are Compton scattered than absorbed through the photoelectric effect in the subject to thereby detect the density variations introduced by the contrast-enhancing agent in the subject spatially resolved.

Abstract: A method for reconstruction of object attenuation density (S(x,y,z)) from X-ray projection image data values (V(pq)) comprises the steps of: representing (11) the object attenuation density by a sum of predetermined continuous harmonics (Hijk(x,y,z)) with unknown coefficients (aijk); relating (12) each of the projection image data values to an integral (S(pq)) of the object attenuation density, and thus to a corresponding sum of sums (aijk*Hijk(pq)) of the predetermined continuous harmonics with unknown coefficients; determining (13) the unknown coefficients (aijk) from the above relation; and reconstructing (14) the object attenuation density by said sum of predetermined continuous harmonics with said determined coefficients. The spatial three-dimensional object attenuation density is found as a continuous function with uniform resolution over all its volume and is shown as a solid three-dimensional body, which can be cut in arbitrary way and shown in continuous motion.

Abstract: A scanning-based radiation detector apparatus for recording an image of an object comprises a 1D detector unit exposed to a fan-shaped ionizing radiation beam, after having interacted with the object; a device for moving the 1D detector unit and the fan-shaped beam relative the object while repeatedly detecting to thereby create a 2D image of the object; and a control device for controlling the repeated detections. The one-dimensional detector unit has an ionizing radiation sensitive thickness, which is larger than the thickness of the fan-shaped beam when impinging on the one-dimensional detector unit. To obtain a short exposure time of each 1D image, but still a high spatial resolution in the 2D image, a 1D image of the fan-shaped beam is recorded every n'th length unit of the movement, where n is not lower than essentially half the thickness of the fan-shaped beam in that length unit, but lower than the ionizing radiation sensitive thickness of the 1D detector unit in that length unit.

Abstract: An apparatus for obtaining tomosynthesis data of an object (5) comprises a radiation source (1) emitting radiation (2) centered around an axis of symmetry (3); a radiation detector (6) comprising a stack of line detectors (6a), each being directed towards the divergent radiation source to allow a ray bundle (b1, . . . , bn, . . . , bN) of the radiation that propagates in a respective one of a plurality of different angles (?1, . . . , ?n, . . . , ?N) to enter the line detector; an object area arranged in the radiation path between the divergent radiation source and the radiation detector for housing the object; and a device (7) for moving the radiation source and the radiation detector relative the object essentially linearly in a direction (8) essentially orthogonal to the axis of symmetry, while each of the stack of line detectors is adapted to record a plurality of line images of radiation as transmitted through the object in a respective one of the plurality of different angles.

Abstract: The present invention relates to a method for reduction of noise in an image including a plurality of pixels, comprising averaging pixel values over a region (R), comprising the steps of: adding a selected pixel to the region (R); grouping pixels adjacent the region (R) in pairs, wherein the pixels of each pair being oppositely located with respect to said selected pixel; adding said pairs, pair by pair, to the region (R) in dependence on the squared difference of the selected pixel value from the pairs half sums does not exceed the dispersion (D) of the noise of said difference multiplied by a tolerance level (L); repeating said step of grouping and said step of adding said pairs until that, in said step of adding said pairs, the condition for adding said pairs is not fulfilled for any pair; averaging the pixel values of said region (R); and using the thus averaged pixel value for the selected pixel of said region (R) in reconstruction of said image.

Abstract: An apparatus for recording a 2D image of an object comprises a plurality of 1D detector units, each exposed to ionizing radiation, as transmitted through or scattered off the object, and being arranged for 1D imaging of the radiation, to which it is exposed. The detector units are distributed in an array such that the 1D images of the radiation from the detector units are distributed over a substantial portion of the 2D image. The apparatus includes a device for moving the detector units relative the object while the detector units repeatedly detect to create the 2D image of the object; and a control device for controlling the detector units to detect ionizing radiation during a short period of time before or during an initial part of the movement; calculating an optimum exposure time for the repeated detection based on the short period of time detection; and controlling the repeated detection to automatically obtain the optimum exposure time.

Abstract: A method for detection of ionizing radiation comprises the steps of (i) directing ionizing radiation towards an object to be examined; (ii) preventing Compton scattered radiation, preferably at least 99% of the radiation Compton scattered in said object, from being detected; and (iii) detecting ionizing radiation spatially resolved as transmitted through said object to reveal a spatially resolved density of said object, wherein said ionizing radiation is provided within a spectral range such that more, preferably much more, photons of said ionizing radiation are Compton scattered than absorbed through the photoelectric effect in said object to thereby reduce the radiation dose to said object.

Abstract: A radiation detector including a chamber capable of being filled with an ionizable and scintillating substance, and a radiation entrance arranged such that radiation can enter said chamber partly for ionizing said ionizable and scintillating substance, partly for being converted into light therein, is disclosed. The detector further includes a light detector for detection of said light, and an electron avalanche detector for avalanche amplification and detection of electrons released as a result of the ionization. Further, there are provided means for correlating detected light and detected electrons, which are derivable from a single radiation photon; and means for producing a signal from the correlated detected light and detected electrons. The detector is particularly suitable for positron emission tomography (PET).

Abstract: A radiation detector comprises two electrode arrangements, each including a dielectric substrate and an electrically conducting layer formed on a first surface of respective dielectric substrate, wherein the electrodes are oriented such that the conducting layers are facing each other. A dielectric spacer is provided to hold the electrodes at a distance from each other to thereby define an inter-electrode space, which, during use, is filled with an ionizable gas. The electrodes are held at respective electric potentials to drift electrons released during ionization of the ionizable gas by external radiation towards one of the electrodes for detection.

Abstract: The present invention relates to an apparatus and a method for detection of radiation comprising at least a first collimator arranged to transmitted radiation through at least a first slit in a Z-direction and prevent radiation in said Z-direction apart from through said at least first slit.

Abstract: A scanning-based radiation detector arrangement for two-dimensional imaging of an object comprises a plurality of one-dimensional detector units, each comprising an entrance slit, through which ionizing radiation as transmitted through the object is entered, and being arranged for one-dimensional imaging of the ionizing radiation, wherein the detector units are arranged in an array on a support with their respective entrance slits being parallel with each other and facing the source of the ionizing radiation. The detector arrangement further includes a rotating device for rotating the detector unit array in a plane perpendicular to the direction of the ionizing radiation, while the detector units are arranged to repeatedly detect, hence creating a series of two-dimensional images of the object.

Abstract: A radiation detector arrangement for imaging of an object comprises multiple line detector units, each being arranged for one-dimensional imaging of the respective ray bundle. The detector units are arranged parallel in a two-dimensional array. The detector units are sited in rows and stacks, the rows being parallel with the detector unit and the stacks being orthogonal thereto, where the one-dimensional detector units in each row are together capable of detecting the object in one dimension. A device is provided for moving the detector units relative the object parallel with the stacks at least a distance corresponding to the distance between two adjacent detector units in the stacks.

Abstract: The present invention relates to an apparatus for detection of radiation comprising a photocathode layer adapted to release photoelectrons in dependence on incident radiation; a radiation entrance arranged such that a beam of radiation can be entered into the apparatus through said radiation entrance and can impinge on said photocathode layer at grazing incidence; an electron avalanche amplifier adapted to avalanche amplify photoelectrons released from said photocathode layer; and a readout arrangement adapted to detect avalanche amplified electrons from said amplifier. The invention further relates to a corresponding method for detection of ionizing radiation and to an arrangement for use in planar beam radiography comprising the detector apparatus.

Abstract: The present invention relates to a flame detector for detection of the presence of a flame or spark in front of the detector comprising a UV sensitive photocathode (12; 21) and an anode (14; 22), respectively, wherein the UV sensitive photocathode is oriented such that UV light from a flame present in front of the detector can strike the photocathode; a voltage supply unit (18; 23) connected to the UV sensitive photocathode and to the anode to force photoelectrons emitted from the UV sensitive photocathode when struck by UV light from a flame present in front of the detector to move towards the anode; and a readout arrangement (15-17; 24) adapted to detect charges induced by electrons moving towards the anode to thereby detect the presence of a flame in front of the detector. The flame detector can be combined with an alarm unit (33) to form an automatic alarm (31).

Abstract: The present invention describes an apparatus for detection of ionizing radiation, wherein the incident radiation ionizes a substance, and the electrons released as a result thereof are accelerated in a dual parallel plate electrode arrangement. These electrons will interact with a scintillating substance to emit light, which is detected by a position sensitive light detector. Since the light is emitted isotropically in such scintillator measures are taken to achieve a good spatial resolution. Thus, the scintillating substance is either arranged in an array of separately located scintillating elements, wherein each scintillating element is separated from the other ones by means of a light impermeable wall, or has an extension in the direction of the accelerated electrons shorter than the absorption length of the light photons emitted in the scintillating substance.

Abstract: An apparatus and method for detecting ionizing radiation are presented. The apparatus includes a scintillator adapted to convert incident ionizing radiation into light; a photocathode adapted to release photoelectrons in dependence on the light; an electron avalanche amplifier adapted to avalanche amplify the photoelectrons; and a readout arrangement adapted to detect the avalanche amplified electrons. The electron avalanche amplifier in one implementation is a gaseous avalanche amplifier including an array of amplification regions. A protective layer is provided to prevent the avalanche gas from coming into contact with the photocathode.

Abstract: A detector for detection of ionizing radiation comprises a cathode; an anode; an ionizable gas arranged between these electrodes; a radiation entrance arranged such that ionizing radiation can enter and ionize the ionizable gas; and a readout arrangement. A voltage across the electrodes causes electrons created during ionization of the gas to drift towards the anode, where the readout arrangement detects them. To reduce the risk of occurrence of sparks, and/or to reduce the energy in occurring sparks, one of the cathode and anode has at least the surface layer facing the other electrode made of a material having a resistivity of at least 5×10−8 &OHgr;m.

Abstract: A method and apparatus for radiography, and a detector for detecting incident radiation. In the method and the apparatus, wherein X-rays (9) are emitted from an X-ray source (60), the X-rays are formed into a planar beam and are transmitted through an object to be imaged (62), and the X-rays transmitted through said object (62) are detected in a detector chamber(64). The detector chamber (64), which detects incident radiation, including electrode arrangements between which a voltage is applied for creating an electrical field, which may cause electron-ion avalanches of primary and secondary ionisation electrons released by incident radiation. The detector (64) is oriented, in relation to the incident radiation (9), so that the radiation preferably enters sideways between a first and a second essentially parallel plate, between which the electrical field is created.

Abstract: A detector for detection of ionizing radiation comprises a first cathode and a first anode between which a first voltage is applicable; an ionizable gas arranged at least partly between the first cathode and the first anode; a radiation entrance arranged such that ionizing radiation can enter and ionize the ionizable gas; and a read-out arrangement. The detector further comprises a second cathode and a second anode between which a second voltage is applicable; and a solid state ionizable material arranged between the second cathode and the second anode such that part of the radiation entered into the ionizable gas can propagate through the gas, enter the solid state material and ionize it; wherein the read-out arrangement is arranged for detection of the electrons and/or holes drifted towards the second anode and/or cathode, respectively, separately of detection of the electrons drifted towards the first anode.

Abstract: An apparatus for planar beam radiography comprises an ionizing radiation source and an ionizing radiation detector; the ionizing radiation source being line-like and extending substantially in a first direction; and the ionizing radiation comprising an elongated radiation slit entrance extending substantially in a second direction and being arranged for one-dimensional detection of radiation from the radiation source entering the detector through the radiation slit entrance. According to the present invention the radiation source and the radiation dectector are oriented such that the first and second directions are essentially perpendicular. Hereby,a facilitated alignment of the detector with respect to source is achieved.