electronic international standard serial number (EISSN)
Small-animal PET/CT scanners provide anatomical and molecular imaging which enables the joint visualization and analysis of both types of data. Spatial alignment of PET and CT modules is achieved by means of a calibration procedure. This step is critical in small-animal imaging since resolution is much higher than in human devices. This work presents an alignment phantom and two different calibration methods that provide a reliable and repeatable measurement of the spatial geometrical alignment between the PET and the CT subsystems of a hybrid scanner. The phantom consists of three glass capillaries filled with a positron emitter solution and positioned inside the system field of view. The calibration methods proposed are both based on automatic line detection, and the results have been tested on a validation phantom, showing an average accuracy of the alignment estimation of 0. 39 ± 0.08 mm over the whole field of view.