Abstract: A gamma camera is made with two rings, each ring bearing a detector. A flap of a support of the detector can be unfolded or folded against a front face of the machine. In the folded position, the machine can be used to carry out tomography scans or standard whole-body examinations. In the unfolded position, the flap enables the performance of whole-body examinations on a bed-ridden patient who remains in his hospital bed.

Abstract: To acquire measurement data elements during a tomography type experiment in nuclear medecine, with a gamma camera having two detector heads, each of these heads is oriented on a sighting center P while the set of two heads rotates about a center of rotation Ia of the apparatus, the center of rotation being offset from the sighting center. It is shown that this approach provides speedier operation for the acquisition and also contributes to the preparation of tomography images that are more precise and more easily computed.

Abstract: A method of decomposition into one component {f.sub.1 }, called the total absorption component, and one component {f.sub.k } called the diffused component of energy spectra {t.sub.i } for N image elements i of a scintigraphic image. The method of decomposition includes the steps of:a) sampling the energy in the form of P samples j;b) recording the values t.sub.i (j) of each spectrum {t.sub.i };c) constructing the table Y of the t.sub.i' (j) values;d) determining the base of specific vectors {v.sub.q } (q=0, 1, 2, . . . , P-1) that are specific orthogonal vectors of the matrix Y, classified by order of decreasing values;e) determining the K fundamental spectra {f.sub.k } in the space generated by the Q (Q.ltoreq.P) first specific vectors {v.sub.q } by applying appropriate constraints to the coefficients b.sub.kq defined by: ##EQU1## f) projecting the image element spectra {t.sub.i } onto the base of the fundamental spectra {f.sub.k } to obtain the decomposition sought.

Abstract: Disclosed is a gamma camera having a base movable on a frame and at least one arm that is movable with respect to said frame and is provided, at one free end, with a plane detector. This camera further comprises two approach planes that are substantially parallel to the plane of said detector so as to servo-control the position of one edge of the patient between these two planes. The invention can be applied especially to gamma cameras that comprise two detectors and are capable of carrying out tomography and full-body examinations.

Abstract: To acquire both a scatter image and an emission image in nuclear medicine, it is chosen to detect the emission image by validating the radioactive events that occur in the nominal range of the radioactive marker chosen. For the scatter image, lower energy ranges are chosen, these ranges corresponding to the production of at least secondary or tertiary Compton photons. It is shown that it is possible, in this way, to reconstruct an artifact-free transmission image. This scatter image is used to correct the initially acquired emission image. It is shown that it is possible to acquire both images at the same time.

Abstract: A method for the correction of uniformity of a gamma camera comprising a detector giving, for each pixel i,j having coordinates x.sub.i, y.sub.i, a number n.sub.ij representing the number of scintillations recorded in said pixel. The method comprises an initial step consisting in:placing a point source at a finite distance from said detector;acquiring the number n.sub.ij at each pixel i,j,computing the parameters x.sub.o, y.sub.o, z.sub.o that minimize the function: ##EQU1## N.sub.ij being defined by the expression ##EQU2## in which: x.sub.o, y.sub.o are the coordinates of the point source in the plane of the detector,z.sub.o is the distance from the point source to the plane of the detector,N.sub.o is the signal at the pixel having coordinates x.sub.o, y.sub.o,multiplying the number n.sub.ij of each pixel by a coefficient proportional to: ##EQU3## Application to medical imaging using gamma camera type display devices.

Abstract: A gamma camera has a base fixed to a frame along a substantially horizontal axis of rotation called the axis of rotation of the gamma camera, bearing at least one arm that is substantially parallel to the axis of rotation and provided, at its free end, with a detector head. The arm is rotationally movable about an axis called an axis of angulation of the detector head, substantially parallel to the axis of rotation of the gamma camera, and passing through the position at which said arm is fixed to the base. In one embodiment, the axis of angulation of the detector head is offset with respect to an axis of orientation of the head toward the head detection surface and passes substantially through the center of gravity formed by the arm and the head. In another embodiment, the end of the arm holding the head has a two-finger gripping piece with bevelled ends.

Abstract: A method of obtaining scatter-corrected images from a nuclear imaging apparatus such as a gamma-ray camera involves the use of a calibration step which measures the energy spectrum response of the apparatus to unscattered gamma-ray events as a function of spatial location, and a correction step which deconvolves the unscattered distribution from a distribution measured in the presence of scatter by using the calculated calibration response function. The method eliminates the necessity of performing a spatially dependent energy correction for detected radiation image events.

Abstract: The noise is eliminated from the images by carrying out a first Fourier transform of the images of an original batch of images. Each of these transformed images is then broken down into Fourier series to reveal the main harmonics of a periodic evolution of the original images and of the transformed images. This harmonic breakdown is used to recompose transformed images that are thus filtered by the abandoning of the non-useful harmonics. The filtered transformed images are used to carry out a reverse Fourier transform to obtain, ultimately, filtered original images. It is shown that the filtering in this case removes the noise without lowering the quality of the structures of the image, without distributing the noise among all these structures.

Abstract: To acquire measurement data elements during a tomography type experiment in nuclear medecine, with a gamma camera having two detector heads, each of these heads is oriented on a sighting center P while the set of two heads rotates about a center of rotation Ia of the apparatus, the center of rotation being offset from the sighting center. It is shown that this approach provides speedier operation for the acquisition and also contributes to the preparation of tomography images that are more precise and more easily computed.

Abstract: The invention relates to a device for an examination bed which is adjustable in height, used particularly for a tomography by scintigraphy. The object of the invention is to enable a large amplitude displacement of the bed along the vertical. It allows to situate the bed, at the maximum position, at a height with respect to the to the ground more than twice higher than the low position. An intermediary carriage (14) is intercalculated between the patient support (13) and the pedestal (15) of the device. The carriage (14) and the patient support (13) move simultaneously and along the vertical with respect to the pedestal (15) of the device. By using a chain (20) whose extremities (26, 27) are fixed to the pedestal (15) and to the patient support (13), and which passes on top of a pulley (19) fixed to the intermediary carriage (14), the patient support (13) is raised by lifting the intermediary carriage (14).

Abstract: A gamma camera includes means for the localization of scintillations produced under the effect of a gamma radiation in a scintillator crystal, the localization means including an array of photomultiplier tubes with gain control obtained by means of calibrated light pulses, and a localization circuit wherein each photomultiplier tube is connected, firstly, through a diode called a resolution diode, to a weighting circuit comprising a network of resistors connected to output adders and, secondly, to a linearizing circuit giving a signal called a linearity signal. The linearizing circuit also gives, for a duration at least equal to the duration of the calibrated light pulses, a pulse to inhibit the resolution diode with respect to the electrical pulses delivered by the photomultiplier tube in response to the light pulses.

Abstract: Improvements are made in the movements of a gamma camera, especially a gamma camera provided with two detector heads, by supporting each of these detector heads with a stirrup provided with two flanks. A bearing can slide within each of the flanks. This bearing holds a pin for the angulation and holding of the detector head. Each detector head can thus be shifted in translation independently, when the two bearings shift together and in the same direction in the flanks. It can furthermore accept a movement of angulation when it is rotated on itself, even about these axes. It is shown that this device improves the ergonomy of use and that it furthermore enables better-quality imaging.

Abstract: A gamma camera is provide, that can be used to measure the coefficient of attenuation of the gamma radiation in a body studied by means of a gamma camera normally made to study the effects of gamma radiation emitted by markers injected into the body. To this end, the collimator is removed from this gamma camera, and it is replaced by a ring and by an arm to which there is fixed a chamber designed to contain a radioactive point source external to the body. It is shown that it is thus possible to obtain images in transmission very swiftly. These images are useful for the correction of normal emission images.

Abstract: A scintillation camera is provided with multiple linearity correction maps which are accessed as a function of the value of the energy of a detected radiation event, so as to separately correct for spatial dislocation errors in multiple energy ranges as a function of detected position. The correction maps may be obtained by direct measurement of nonlinearities for each of the desired energy ranges individually, or sets of corrections for some energy ranges may be obtained by extrapolation calculation from correction factors which have been obtained by direct measurement.

Abstract: The disclosure relates to devices for medical imaging by gamma rays. In a device where a gamma camera is suspended from a supporting frame by a rotating stand, an arm and two pins enabling two movements of rotation of the detector head of the gamma camera with respect to the rotating stand, there is provided a stirrup connected to the arm by a third pin enabling a third rotational movement about this gamma camera. It makes it possible to facilitate the relative movement of the gamma camera and of the patient undergoing the examination.

Abstract: The system includes a frame provided with jaws (8, 9) for grasping the collimator. The collimator and the case include a system of retractable studs that co-operate with reaction members to retain the collimator (2) on the case (5). The jaws act on the studs (46) to detach the collimator from the case while simultaneously grasping the collimator. It is shown that by acting in this way, the collimator is permanently retained and simultaneously collimator installation and fixing operations are facilitated.

Abstract: A Compton scatter camera for nuclear medical imaging includes an annular scattered photon detector disposed around a first scattering detector and shielded from the field of view of incident gamma photons. Scattered photons detected by the annular detector are thus scattered through angles greater than those of a conventional Compton scatter geometry. Sensitivity and count rate capability is thus significantly increased over the conventional scatter camera, so as to present the possibility for a commercially feasible Compton scatter camera to be realized.

Abstract: In order to change from antero-posterior examination to lateral examination with an osteodensimeter, the yoke carrying the X-ray tube and the radiation detector of this apparatus is moved laterally. Changeover of the entire assembly is enabled when this lateral translation comes into abutment. When changeover is complete, the return transverse translation is performed. Prior to performing lateral examination, the bed on which the patient to be examined is lying is itself raised. It is shown that this dynamic configuration makes it possible to keep the position of the X-ray tube relative to the detector fixed and as adjusted by construction.

Abstract: Gamma camera equipment of the invention has two detector heads capable of being associated for whole body type examination in which the two detector heads co-operate, or else of being separated for tomographic type examination, where only one of the heads is in use nevertheless continuing to be powered. In order to reinforce the mechanical cohesion of the assembly, the lower detector head is displaceable on rails which are fixed to the stand on which the upper head is mounted so that the stand constitutes a counterweight for the lower head, with struts being provided at the end of the rails only. The invention is particularly suitable for making compact multi-analysis equipment suitable for installation on any type of floor.