Development of a high resolution, 2D detector system for iodine-131-scintigraphy

During a I-131 therapy of benign and malignant thyroid diseases, precise information about tracer distribution is helpful for patient management. However, the use of established Anger technique for I-131 scintigraphy is difficult because of septal penetration inside the collimator. The aim of this study is to develop a two-dimensional I-131 detector with high spatial resolution and patient-friendly acquisition time. The main components of the authors' system are a position sensitive photomultiplier, EGO scintillation crystals inserted into a lead matrix, a parallel hole collimator and a translation unit to realize well defined displacements. Thus, the septa thickness can be chosen to reduce the septa penetration significantly. Thick septa cause "dead areas" on the photomultiplier. These gaps are filled sequentially by well defined displacements in the projection plane. The individual scintigramms at the different measured positions are composed to a final image. Using the described detector geometry, all details and structures of the measured phantom were visible in a measurement time of 16 minutes. Therefore the developed system is especially suited for I-131 thyroid scintigraphy.