Matched Collimators for Pixellated Gamma Cameras

Comparison of breast specific gamma imaging and molecular breast tomosynthesis in breast cancer detection: Evaluation in phantoms

“…Parallel hole collimators whose hole shape and pitch are designed to match those of the detector elements can theo-retically improve sensitivity compared to conventional unmatched (nonmatching shape or pitch) collimators if they are precisely aligned so that the collimator septa overlie the inactive areas between detector elements. 25,26 The amount of sensitivity increase possible through the use of matched collimators depends on the open area fraction of the crystal array, the accuracy of collimator and crystal array fabrication, and precision of alignment. The amount of possible improvement is reduced as the divergence of the gamma rays exiting the collimator increases (i.e., with decreasing hole length-to-diameter ratio) and with increasing gap size between the collimator exit surface and detector entrance surface.…”

Optimization of convergent collimators for pixelated SPECT systems

“…11,26 For a matched collimator design, each hole and its corresponding pixel is independent of other holes and pixel units. 9 Thus, the system resolution (collimator and detector combined) is determined only by the collimator resolution, offering improved spatial resolution compared to conventional collimator hole designs. 7 In addition, since the active portions of each detector pixel are aligned with the collimator holes rather than being covered by the septa, the efficiency of the system is maximized.…”

“…This kind of collimator is designed to have a square hole shape to exactly match the active areas of the detector elements. 9 In these studies, innovative optimal collimator designs, compared to the ones used for conventional nuclear medicine, were obtained. 7 However, due to manufacturing problems of converging collimators and its design (more complex than that of parallel hole), few efforts were made to solve the theoretical problem of their optimization.…”

Design of optimal collimation for dedicated molecular breast imaging systems

“…28 Also, the alignment of the septa with detector elements eliminates any possible aliasing patterns that can arise due to mismatch of hexagonal collimator holes and square pixels. 17 One constraint necessary for a matched collimator design is that the size of a collimator lattice unit, d + t, must equal the size of each detector element, or the pixel size p. When this requirement is introduced, solving for the optimal hole dimensions becomes an iterative procedure.…”