Abstract :
A modular, digital system, fully programmable and scalable for a multi-modality, open (to accommodate claustrophobic or overweight patients, with the option of closing the detector, to increase efficiency), 3-D Complete Body Scan (3D-CBS) utilizing both positron emission tomography (PET) and Computed Tomography (CT) in one unit with no moving parts, has been designed for VME and IBM-PC based platforms. This device fully exploits the double photon emission and allows for annual whole-body screening for cancer and other systemic anomalies; only 1/30 the radiation dosage; a reduction in scan time to 4 minutes for a field of view (FOV) of 137.4 cm as opposed to 55 minutes for a FOV of 70 cm; a decrease in examination cost by 90%; an increase in sensitivity, providing physicians with additional clinical information on a specific organ or area and contribute to the specificity in detecting and assessing cancer. These advantages allow for early detection-the best way to defeat cancer. The system collects digital data from multiple electronic channels. Each electronic channel carries the information (64-bit) of all sensors included in a given view angle of the detector. The 64-bits data packets acquired at 20 MHz by each channel with zero dead-time are correlated with neighboring information and processed in real time by a 3D-Flow DSP to improve the signal-to-noise ratio and extract and measure particle properties, resulting in the identification of the particles´ position, accurate energy measurement, depth of interaction (DOI), and the timing measurements. A thorough real-time algorithm that best identifies the photons can be executed because the 3D-Flow sequentially-implemented, parallel architecture (SIPA) allows for processing time to be extended in a pipeline stage beyond the time interval between two consecutive input data. Very low power consumption drivers drive short, equal-length PCB traces between 3D-Flow chips, solving the problem of signal skew, ground bounce, cross-talk and noise. The electronics validates and separates events from the different modalities (PET/CT); PET events are checked for coincidences using a circuit sensitive to radiation activity rather than the number of detector elements. Both PET and CT examinations occur at the same time in a stationary bed position using a detector with a long FOV, avoiding motion artifacts, increasing throughput, reducing examination cost, reducing radiation to patients, increasing resolution, improving data quality, and reducing erroneous readings (false positives). The saturation of the electronics of current PET is eliminated by using a system with an input bandwidth of 35 billion events per second distributed over 1,792 channels. The output bandwidth is selectable to sustain the activity generated by the maximum radiation that a PET/CT should ever receive. The overall events are gathered by IBM PC or VME CPU board, formatted and sent to the image processing workstation. The entire system can be simulated from top level to gate level before construction
Keywords :
computerised tomography; data acquisition; medical diagnostic computing; positron emission tomography; IBM PC; VME; data acquisition system; depth of interaction; field of view; multi-modality PET/CT scanners; parallel architecture; positron emission tomography; signal-to-noise ratio; Bandwidth; Cancer detection; Computed tomography; Costs; Data acquisition; Energy measurement; Particle measurements; Position measurement; Positron emission tomography; Radiation detectors;