Data Spectrum Corp. REFERENCES

tors with shorter in-plane focal length and longer axial focal length can minimize the inadequate axial sampling while maintaining a gain in sensitivity. With the use of astigmatic HCB collimators, the in-plane focal length can be shortened to obtain better tradeoff between resolution and sensitivity. With triple-camera SPECT systems, another solution is to combine HCB, fan-beam and parallel-beam collimators to obtain adequate axial sampling. Si multaneous acquisition can be performed with triple-camera sys tems by using two HCB collimators and a single parallel-beam or fan-beam collimator (21). The loss in overall sensitivity (relative to the use of three HCB collimators) is only about 15%-20%