Measuring the imaged-object distance with a stationary high-spatial-resolution scintillation camera

A method to measure the detector-to-object distance from the images obtained with stationary high-spatial-resolution gamma-ray cameras for in vivo studies has been developed. It exploits the shift of the imaged object in the image plane, obtained at a certain tilt of the parallel-hole collimator. A linear dependence of the image displacement on the distance to the object has been measured using a high-spatial-resolution scintillation camera employing an yttrium-aluminium perovskite (YAP) scintillator. It is shown that the modified YAP camera can be used to obtain three-dimensional information without moving the camera or the object. The method could be applied in scintimammography and radioguided surgery, in lymphoscintigraphy, as well as in the analysis of the biodistribution of radiopharmaceuticals.