Abstract: A gamma ray collimator assembly comprising a first portion and a second collimator portion, the first and second portions having different gamma ray acceptance angles.

Abstract: A gamma camera head including: a plurality of signal sources, each associated with a pixel position, the source producing a signal when a gamma ray absorption event occurs at or sufficiently close to its associated pixel, wherein the plurality of signal sources is associated with a contiguous extent of pixels; and a plurality of electronic circuits, each of which receives signals from at least two of the plurality of signal sources, wherein each circuit receives the signals only from sources associated with non-contiguous pixels.

Abstract: A method of calibrating a PET (Positron Emission Tomograph) scanner includes:acquisition of data from a plurality of coincidence radiation events, using at least one detector; anddetermination of values for a set with at least one calibration factor, which factor affects an analytically defined calibration criterion. Preferably, the detector has at least one rotating planar detector and the acquisition of data includes acquiring data from a plurality of rotational positions of the detector.

Abstract: A method of acquiring an analog electrical pulse signal caused by a radiation event impinging on a detector crystal and viewed by a plurality of detector units. An image is formed based on a plurality of the events, each of which is captured by some of the detector units. The method of acquiring includes.(a) adding a linearity enhancement signal to the analog signal; and(b) converting the analog signal to a digital signal, where the linearity enhancement signal is slowly varying relative to the length of an analog signal pulse. Alternatively or additionally, a resolution enhancement signal is added to the analog signal before (b) converting the analog signal to a digital signal. The resolution enhancement signal varying relatively quickly compared to the length of an analog signal pulse.

Abstract: A system for recording fewer of the events that are caused by unwanted photons with greater stability. The system locally determines the energy spectrum and fits for each pixel of the image the determined energy spectrum with a modified trial function composed of: a photopeak component of known energy shape, Compton scatter components having theoretically derived energy shapes and, when applicable, also measured or calculated energy spectra of other unwanted photons. The modified trial function also takes into consideration unknown local deviations in the outputs of electronic components. The amplitude of the photopeak distribution resulting from the fit is used to obtain the local content of wanted interactions in the image. This enables removal of Compton contamination and also the contamination caused by interaction of the gamma photons with lead components.

Abstract: An interpolation filter that enables interpolation without changing the values of the interpolated points coinciding with the sampled data points, the signal content of the original image, or the variance of the original image.

Abstract: A gamma camera that iteratively determines corrected X, Y coordinate locations of events based on optimizing an event location function for each PM using the distance between the event and the PM's.

Abstract: A system for recording fewer of the events that are caused by unwanted photons with greater stability. The system locally determines the energy spectrum and fits for each pixel of the image the determined energy spectrum with a modified trial function composed of: a photopeak component of known energy shape, Compton scatter components having theoretically derived energy shapes and, when applicable, also measured or calculated energy spectra of other unwanted photons. The modified trial function also takes into consideration unknown local deviations in the outputs of electronic components. The amplitude of the photopeak distribution resulting from the fit is used to obtain the local content of wanted interactions in the image. This enables removal of Compton contamination and also the contamination caused by interaction of the gamma photons with lead components.

Abstract: A system for recording fewer of the events that are caused either by Compton scatter photons or by gamma radiation interacting with lead. The system locally determines the energy spectrum and fits the determined energy spectrum with a trial function composed of a photopeak component of known energy shape, but unknown magnitude and a Compton scatter component having a theoretically derived energy shape and an unknown magnitude for each pixel of the image. The trial function is locally fitted to the measured energy spectrum to obtain the values of both the Compton Coefficient and the gamma radiation interacting with lead. This enables removal of Compton contamination and also the contamination caused by interaction of the gamma photons with lead components.

Abstract: Correction for Compton scattering is effected by analysis of the energy spectra. More particularly, a measured energy spectrum is constructed per location from detected counts that are stored according to their measured energy as well as according to the location of gamma ray infingement on a scintillating detector. The measured spectrum comprises scattered and unscattered photons. A physically correct trial function enables the separation of overlapping contributions of scattered and unscattered photons. The trial function includes multiple collision terms that are preferably constructed using the Nishina-Klein equations describing photon Compton scatter probability distributions. The count of unscattered photons per location is derived from the measured spectrum by locally fitting to the trial function. The count of the unscattered photons per location is used to produce the improved images with reduced artifacts caused by Compton scatter.

Abstract: In-vivo bone density measuring system using a modified emission computed tomographic gamma camera arrangement for detecting radiation from two separate sources located outside of the body of the patient and oppositely disposed to the gamma camera during rotation of the gamma camera and sources means about the patient for obtaining tomographic data. The two separate sources emitting at least two energy levels. The system includes processing means for the detected radiation to provide a bone mineral density map.