The Design Of High-speed Data Transmission System For PET Based On TCP/IP

Tumor, cardiovascular disease and nervous system disease are great threat to human beings' health, With the fast development of Nuclear technology and the advantages of modern electronic technologies, PET(Positron Emission Computed Tomography) becomes an important medical equipment that can dynamically and quantitively monitor the physiological metabolism of living body in a noninvasive way. Many high efficent detector modules compose the PET ring detector, all the modules work simultaneously to acquire massive data which help to improve the PET spatial resolution, and thus more accurately locate the organ physiological metabolism.On account of the demand for great volume of data transmission at high speed, this paper adopts standard TCP/IP protocol and advanced Gigabit Ethernet technology to design the high speed data transmission system for PET.This paper proposes to design two independent modules, namely data acquisition circuit board for front-end detectors and high speed data transmission circuit board,taking the whole PET electronic system in account.PCI, VME and other kinds of bus are currently adopted for the PET data transmission, but they are not flexible enough to modify or upgrade the hardware for PET system with so many detector modules.Thus this paper adopts Gigabit Ethernet to transmit PET data after technical research.The scheme is operated as follows: The high speed ADC acquires the analog signal emitted by the detectors. FPGA is choosed to be the core chip for the data transmission circuit board, a PHY IP core and an IP core that contains MAC controller and TCP protocol packaging circuit are choosed to encapsule data for Ethernet transmission. It helps to minimize the size of circuit board because all operations are completed in only one chip. The data transmission circuit board can simultaneously deal with several detectors' signal from the PMC port owing to the plentiful I/O pins of FPGA that can be freely defined. And also, the data transmission circuit board has a port compatible with SFP module, which helps to transmit data to PC through opticalfibre. In the course of implementing this scheme, I designed the analog signal acquistion circuit, peripheral circuit of FPGA chip, TCP/IP protocol packaging module, the hardware design for signal transmission port and developed desktop software for data acceptance. The design realizes the demand for reliable data transmission at high speed.The speed of data transmission of the designed PET data transmission system reaches 360 Mbps. This experiment result indicates the demand of data transmission speed is met by the designed system.