Abstract: An apparatus for controlling a relative distance between a patient's body and a camera head in a medical imaging system is disclosed. The apparatus comprises (a) a light source provided at one side of a field of view, which is defined by a camera surface of the camera head, and (b) a light detector provided at the other side of the field of view. The light detector is adapted to detect a light beam emitted by the light source. The apparatus includes means for adjusting a relative distance between the patient's body and the camera surface by sensing an interruption or disturbance in the light beam caused by the patient's body approaching the camera surface to take a picture. A method of controlling a relative distance between a patient's body and a camera head in a medical imaging system is also disclosed.

Abstract: An apparatus for controlling a relative distance between a patient's body and a camera head in a medical imaging system is disclosed. The apparatus comprises (a) a light source provided at one side of a field of view, which is defined by a camera surface of the camera head, and (b) a light detector provided at the other side of the field of view. The light detector is adapted to detect a light beam emitted by the light source. The apparatus includes means for adjusting a relative distance between the patient's body and the camera surface by sensing an interruption or disturbance in the light beam caused by the patient's body approaching the camera surface to take a picture. A method of controlling a relative distance between a patient's body and a camera head in a medical imaging system is also disclosed.

Abstract: A method and apparatus for determining the centre photodetector in a planar array of photodetectors of a gamma scintillation camera is provided. The analog signals generated by a plurality of photomultiplier tubes (PMT) following a scintillation event, are digitized, integrated, and stored in a first memory. A first comparison means is used to divide the set of PMT logical signals into groups. Each group comprises an arbitrary number of PMTs. The PMT logical signals within a group are combined into pairs and compared to select the highest intensity value for each individual group. Subsets of local PMT highest intensity values are created. A second comparison means is used to receive the subsets of local PMT highest values, combine them into pairs, compare the paired signals, and record the selected signals in a second memory, until a PMT with the maximum intensity value or a centre PMT is obtained.

Abstract: A control circuit for a scintillation camera is provided in which only discrete scintillation events are processed. When a scintillation event arrives, all light intensity signals below a predetermined threshold, indicating that the signals below the thresholds are not likely to be involved in the event, are blocked from the sum signal. The valid event discrimination circuit disclosed considers the sum signal of light intensity signals originating from only those photodetectors whose output signals are above the threshold. Valid event discrimination is not adversely affected by signals coming from photodetectors not involved in the event after the threshold detection takes place.

Abstract: Digital intensity values from a planar array of photodetectors optically coupled to a scintillator in a digital electronic scintillation camera are compared to one another from most significant bit down to least significant bit in order to determine within the limits of precision of the digital values which photodetector has the maximum light intensity. Center photodetector determination is an important part of efficient position calculation in a scintillation camera.