基于硬件实现的锥束CT图像重建系统的存储机制设计

为了实现三维锥束CT图像重建加速系统的小型化,建立了基于FPGA的三维图像重建系统。并对该系统中所采用的FDK重建算法所需的数据存储量和数据传输量以及由SDRAM、SRAM和FPGA内部缓存组成的存储系统的数据吞吐率进行了研究。首先,根据FDK算法的滤波与反投影两个步骤介绍了三维锥束CT图像重建系统的数据规模。接着,介绍了一种以SDRAM为外部主存,以SRAM为外部缓存和以FPGA内部SRAM资源作为内部高速缓存的存储机制。然后,介绍了该存储机制的实现方法以及测试方法。最后对该三维图像重建系统的数据吞吐能力进行了测试,并将之与FDK算法所需的数据传输量进行了对比分析。试验结果表明:该存储机制的数据连续存取速度为151.9MB/s,数据随机存取速度为100MB/s,基本满足小规模的三维图像重建的数据存储与传输带宽的要求。

A Storage Method of 3D CT Image Reconstruction System

In order to realize the miniaturization of three-dimensional cone-beam CT image reconstruction system to small-scale,A three-dimensional image reconstruction system based on FPGA is established.The memory bandwidth requirement of the FDK reconstruction algorithms and the data throughput of the storage system which is composed of SDRAM,SRAM and the internal R AM resource of FPGA is introduced.First,based on filtering algorithms and back projection algorithms the memory bandwidth requirement of a three-dimensional cone-beam CT image reconstruction system is studied.Then,a data access scheme is presented,which uses a SDRAM chip as its main storage a SRAM chip as its external cache and the SR AM resources of FPGA as its internal cache.Then,the process of the implementation and the testing methods of the storage scheme is introduced.Finally,data access capacity of the three-dimensional image reconstruction system was tested.Experimental results indicate that:the storage system can achieve a sequential access data rate of 151.9MB/s and a random access data rate of 100MB/s.It can satisfy the memory bandwidth requirement of a small-scale three-dimensional image reconstruction system.