Comparison of two systems of multiple line sources for SPECT transmission scanning

The authors have proposed a new design for a transmission source which uses a system of multiple parallel line sources. It does not require complicated hardware, it allows the activity distribution to be tailored to the shape of the human body, minimizes both the amount of activity being used and patient dose, and substantially reduces the problem of low counts in transmission scans which can arise when large patients are scanned. The authors have built and investigated two systems based on line sources, namely the Collimated Line Sources (CLS) (10 lines) and the Multiple Line Array (MLA) (20 lines). Since they use different source positions and collimations, the systems require different approaches to the data processing and map reconstruction. This study presents a comparison of the results of simulations and phantom experiments performed using these two systems. Qualitative and quantitative analyzes of the attenuation maps were performed. The results of the authors' tests showed that transmission maps obtained with multiple line sources are artifact free, have good uniformity, 2-3% accuracy, about 1-1.5 cm resolution, and acceptable levels of noise. Preliminary simultaneous emission/transmission studies using MLA system and involving both phantom and patients have demonstrated that these maps can be successfully used to correct for attenuation.