The clinical application of OSEM SPET reconstruction in a standard PC Windows environment

Full text: Although iterative reconstruction techniques have existed at least as long as the more common filtered back-projection (FBP) techniques, one of the limiting factors in their incorporation into routine clinical use has been the demands placed on computer processors. This invariably meant either prohibitively expensive computer hardware to deal with the complex algorithms, or painstakingly slow reconstructions on anything but the most current gamma camera computers. Our intention was to implement the accelerated version of the maximum likelihood algorithm, ordered subset expectation maximization (OSEM), developed by Hudson and Larkin on existing PCs in the department simply and for little more than the cost of the software. Our Siemens ICON computers, running on a Macintosh platform, were connected to a standard 300 MHz PC running Windows NT. Through the use of an inexpensive, off-the-shelf software application, the PC and Macintosh were set up for direct file transfer. The SPET study acquired on a Siemens MS3 was exported to the PC via interfile format, and imported again following reconstruction. Processing times for the OSEM method on the PC ranged from 30 to 400 s depending on the SPET data format, number of iterations and other parameters used. Most reconstructions were below 1 min for full frame reconstruction. The ease and relatively small cost of such an installation and implementation of the OSEM software means that most departments already have the hardware necessary to incorporate iterative reconstruction algorithms