Abstract: Scatter errors are eliminated from a gamma camera image on a spatially dependent basis. A global scatter curve is obtained and normalized for each local area. Based on this local scatter curve and the local spectrum, a local correction factor is obtained. The correction factors are then used to remove scatter errors from the image. The method provides spatially-dependent correction based on measured scatter. It does not require the camera's zero-scatter response to be known and it does not require the fitting of spectra either by a polynomial or by a theoretical scatter function. It allows for rapid determination of scatter correction factors for each pixel in an image. It produces excellent results for both transmission and emission images.

Abstract: A gamma camera is calibrated at different photon energies to provide several different calibration arrays. The calibration arrays are used to correct the camera image according to the energy of the photons detected from the body to be examined. The calibration array obtained from the photons having an energy closest to the photons detected from the body may be used. Another alternative is to form an interpolation array based on two or more calibration arrays obtained with photons having energies bracketing those from the body.

Abstract: An imaging detector on a medical imager is provided with a proximity sensor for automatically maintaining a desired distance from the subject to be imaged. The proximity sensor is formed from three infrared beams at decreasing distances from the imaging detector. The imaging detector is moved toward the subject until the first two beams are interrupted. If the third beam is interrupted, the imaging detector is moved back from the subject until only the first beam is interrupted. Faults are detected by monitoring the order in which the beams are interrupted, whether the beams are interrupted when the imaging detector is fully retracted, and whether beams are present when no signal is applied to the beam emitters.

Abstract: A gantry and pallet assembly using scintillation cameras to acquire data emitted from radiopharmaceuticals previously introduced into a patient. The radiopharmaceuticals accumulate in a predetermined region of interest within the patient. The gantry can perform both whole body and single photon emission computed tomograph (SPECT) scans. The gantry has two scintillation cameras mounted in a diametrically opposed manner on and in close proximity to a rotation ring. Each camera can be radially translated relative to the rotation ring simultaneously with the rotation of the rotation ring. The gantry is capable of being translated along a pair of translation tracks so that a pallet upon which a patient lies passes therethrough. The pallet assembly has a storage carriage which supports a substantially rectangular flat pallet upon a slidable frame, and a curved pallet upon an extension assembly. The storage carriage can be slid away from the gantry or close to the gantry.