Apparatus and method for large field-of-view measurements of geometric distortion and spatial uniformity of signals acquired in imaging systems

A method for image quality assessment of an imaging system, comprising:

• locating, within the imaging system, an aggregate phantom having multiple self-contained sections, each section including fiducial features of known relative location,
• creating an image of the aggregate phantom with the imaging system, and
• with a processor:
• quantitatively determining location of the fiducial features within the image,
• comparing the determined location within the image to the known relative location of the fiducial features to produce a distortion field, and
• distinguishing between actual geometric distortion of the imaging system and rigid-body transformations of the sections of the aggregate phantom, in the distortion field.

A method for performing distortion measurements of an imaging system with a phantom over a field of view larger than an imaging volume of the phantom, comprising:

• acquiring a set of images, with the imaging system, of the phantom positioned at multiple locations within the field of view,
• combining the set of images to form an extended image,
• determining a distortion field of the extended image, and
• distinguishing between actual geometric distortion of the imaging system and rigid-body transformations attributable to repositioning of the phantom, in the distortion field.

A method for measuring spatial uniformity of a signal acquired by an imaging system, comprising:

• locating a phantom within the imaging system,
• attributing virtual features to regions at known locations throughout a measurement volume of the phantom, each region containing only background liquid,
• imaging the phantom with the imaging system, and
• with a processor:
• measuring average signals within the regions, and
• interpolating between the average signals to determine spatial uniformity of a signal acquired by the imaging system, throughout a measurement volume of the phantom.