Stepped asymmetric sampling scheme for transmission radiation corrected gamma cameras

A positron emission tomographic camera comprising:

• a rotating gantry which defines a subject receiving aperture;
• a rotational drive for stepping the detector heads around the patient receiving aperture in even steps with the steps in one half rotation offset from steps in an opposite half rotation offset by one half of the even step;
• a plurality of radiation detector heads movably attached to the rotating gantry, said detector heads rotating about the subject receiving aperture with rotation of the rotating gantry;
• at least one radiation source mounted to at least one detector head such that transmission radiation from the radiation source is directed toward and received by a corresponding detector head positioned across the subject receiving aperture from the radiation source;
• an angular position sensor which senses the angular position of the gantry and each detector head attached thereto as the gantry rotates about the subject receiving aperture;
• and
• a reconstruction processor which reconstructs the emission and transmission data into a volumetric emission image representation.

A method of sampling transmission radiation data and emission radiation data from a radiopharmaceutical injection for use in diagnostic imaging, said method comprising:

• (a) selecting a rotation increment for effective emission data imaging resolution;
• (b) incrementally rotating a radiation source and radiation detectors about a subject receiving aperture by a predetermined step size over a first 180° of one complete rotation about the subject receiving aperture;
• (c) incrementally rotating the radiation source and radiation detectors about the subject receiving aperture by the predetermined step size over a remaining second 180° of one complete rotation about the subject receiving aperture offset by a half step relative to the first 180° of rotation;
• and
• (d) detecting radiation emitted by the radiopharmaceutical and the radiation transmitted by the radiation source at each stepped angular orientation corresponding to each incremental rotation about the subject receiving aperture.