Multi-divergent-hole cardiac SPECT

Objectives A challenging issue in a stationary SPECT system is to provide sufficient number of view-angles of the object. Thus a stationary imaging system must form reduced images of the object to fit many images into a given detection area. This paper claims that the multi-divergent-hole (MDH) collimators can give better performance than the multipinhole (MPH) collimators in stationary human cardiac SPECT.

Methods Currently the stationary cardiac SPECT system uses MPH technology, because when the object is far enough from the pinholes, the images are smaller than the objects so that many images can be obtained at different view-angles in the limited detection area of a stationary system. A drawback of the MPH collimator is that the view-angles from one collimator are clustered together, and system may not be able to provide enough angular spread for tomography. The MDH collimators can also give reduced images. The MDH collimation has two advantages over MPH : 1) In image reduction mode, the MDH system has better detection sensitivity than MPH with the same resolution; 2) The MDH system has a wider angular spread than MPH.

Results The pinhole and divergent-hole resolution and sensitivity are compared. Numerical simulations show that the divergent-hole system has approximately twice the sensitivity as pinhole with the same resolution. The angular spread of an MDH system is about twice as large as that of an MPH system with the same image reduction factor and the same collimator-to-object distance. An MDH system with 3 detector-heads can cover a range of view-angle of 180°C, which is enough to provide a satisfactory image.

Conclusions A stationary cardiac SPECT can be built by using MDH collimators, instead of MPH collimators; the MDH system provides better angular sampling, superior sensitivity/resolution trade-off, and no multiplexing.