Abstract: A network for use in a fourth generation CT scanner for noise reduction. The network comprises an active low pass filter whose cutoff frequency is controlled by a scaled signal responsive to the angular velocity of the rotating radiation source of the scanner. In a preferred embodiment a raw signal is generated by an encoder that detects movement of the source. As the source speed changes either in response to an operator's selection of a different scan speed or to systemic variations in the scanner relative to expected performance, the filter's cutoff frequency will automatically change thereby assuring optimum performance regardless of scan speed.

Abstract: A CT scanner having an outer circular array of stationary radiation detectors for an inner concentrically revolving source of radiation emitted in a fan pattern subtending a number of the detectors. Each grouping of 15 consecutive detectors is housed in a detector module, each one of which is provided with an electro-optical device which is arranged to normally deactivate the output of each of the detectors in the module. The detectors are arranged in exclusive groups of four nonconsecutive detectors each equiangularly disposed about the array connected in daisy chain fashion with the output of each of said nonconsecutive detector groups applied to a single signal cable defining a corresponding signal processing channel.

Abstract: The current amplifier with automatic drift correction is designed for use in conjunction with computerized tomographic scanners or other apparatus. The amplifier comprises a differential amplifier with a first input connected to a photodiode or other source of current to be amplified. An integrating amplifier is connected between the differential amplifier output and a second differential amplifier input. The integrating amplifier has a time constant which is long compared with the period during which the diode current is to be amplified to provide automatic drift correction. A feedback loop connects the output of the differential amplifier with the first differential amplifier input. The feedback loop comprises a pair of matched transistors interconnected to form a current mirror. A first resistor connects the current mirror with ground. Current flow through these two resistors is summed to form the current flow received by the current mirror.

Abstract: A tomographic scanner for subjecting a planar region of a patient to radiation and producing an image representing the planar region in which at least the source or beam of radiation is moved with a varying speed. In particular, in a traverse and rotate type scanner, a carriage carrying the radiation source and detector(s) is traversed relative to the patient with generally simple harmonic motion. Additionally, vibration is reduced by using a motor, which may include a flywheel, running at substantially constant speed to traverse the carriage. Vibration is further reduced by connecting the motor for rotating the carriage to the carriage through a flexible, e.g. chain, drive. Cable connections to the X-ray tube and other elements carried by the moveable carriage are simplified with a bicycle-chain like flexible cable support.