Multiple window spatial registration in gammacameras using a phantom for spatial linearity evaluation

Abstract

In the present paper, an alternative methodology to perform the multiple window spatial registration test in gamma cameras is proposed. A home-made phantom, developed to evaluate the spatial linearity of a gamma camera, is used. The phantom is made with a plate of lead, 3 mm thick, which contains a set of 5 mm diameter holes arranged in a 17 × 17 matrix. The distance between adjacent holes is 2 cm. A syringe containing a small volume of ⁶⁷Ga (no more than 0.1 ml) and a 0.1 mCi activity, located 2 m away from the detector, is used as a point-like source to illuminate the phantom. Data have been collected from two different gamma cameras to validate the method. In order to automatize the data analysis, an ImageJ macro was programmed at our institution. The obtained results do not exceed the maximum values recommended by the Spanish Protocol (1 mm), so they are considered as satisfactory. The method proposed here entails a considerable reduction of time regarding both image acquisition and analysis. It also involves a time reduction regarding source manipulation and, as a direct consequence, a lower risk of radiation contamination associated with the procedure.