Collimator design for single photon emitter

The aim of this study is to develop a new light collimator with the same efficiency in terms of photon penetration as that of the conventional collimator. Generally the conventional collimator is an over specification in terms of the path length in the material forming the collimator. If the path length of a gamma ray in the septum is short, many photons may pass through the septum and the septum does not work as a shielding material. On the other hand, if we consider a path which is located near the center of the septum, it is sufficient to shield from undesirable gamma rays. So we gave up using the plane-septum structure that is used in the conventional collimator. In the new collimator we made several spaces where the septa are located in the conventional collimator. One realistic form of the collimator is composed of many rods whose cross-section is square or circular. The collimator is composed of rod-shaped lead or tungsten in x- and y-directions alternately with spacing in z-direction (direction of thickness). Even though we align many rods alternately without spacing in z-direction, we can achieve a collimator with less than half the weight of a conventional collimator. Performance of the proposed collimator was confirmed by Monte Carlo simulation.