Design Of Stationary Digital Breast Tomosynthesis Control System Based On Carbon Nanotube X-ray Source

Breast cancer is now the most frequently diagnosed cancer in Chinese women, early detection, diagnosis, treatment is the key to reduce breast cancer mortality. With the application of Full-field digital mammography, had been improved the resolution of x-ray signs about breast lesions obvious. So as to provide the basis for breast cancer early diagnosis and treatment. But the current digital breast tomosynthesis x-ray source adopts hot cathode x-ray source, in order to obtain different x-ray scanning Angle, xray source is mounted on a rotating gantry and moves along an arc during the scan. Because of motion artifact caused by the mechanical movement and time delay by thermionic emission mechanism, led to reduce spatial resolution and long scanning time increase the patient radiation dose.This article was improved the x-ray source system in view of the current digital breast tomosynthesis, using carbon nanotube field emission cathode x-ray source to replace the traditional hot cathode x-ray source. Compared to the traditional thermal emission X-ray source, CNT X-ray source possesses several desirable attributes such as miniaturization, fast response time, efficient-focusing and improved control of emitted electrons, so can use electronic scanning mode instead of traditional scanning mode, improve the acquisition image spatial resolution, reduce the radiation dose. Main content of this paper is design stationary digital breast tomosynthesis(s-DBT) control system based on CNT x-ray source.First, introduces carbon nanotube field emission theory and the principle of sDBT, specifically on Triode-type field emission x-ray tube, multiple beam field emission X-ray source device, and stationary scan mode in details.Then, the s-DBT control system hardware and software are designed, hardware circuit implementation of 31 channel pulse output, 31 distributed control of the carbon nanotubes x-ray source array corresponding to each emission unit; And output a synchronized trigger signal, the realization of synchronous work both x-ray source and detector. Multi-channel pulse signal and synchronization trigger signal generated by FPGA as the core of the controller hardware circuit. Software platform design is divided into PC software and slave computer software, the slave machine adopt the Quartus II software development platform, programming language use verilog hardware description language to realize 31 channel pulse and the realization of a trigger signal. PC software platform using Lab VIEW graphical programming tools, in addition of slave machine through serial bus pass pulse parameters, Through the Lab VIEW virtual instrument control function, integrate control gate high voltage power supply, anode high voltage power supply, compound vacuum gauge and Pax Scan2520 D detector complete s-DBT multiple beam x-ray source stationary scan and image acquisition function.Finally, the s-DBT control system of multi-channel pulse module and synchronization trigger module experiment verification, and complete through the experiment of carbon nanotube field emission performance test and multiple beam xray stationary scan.