TOMOGRAPHIC IMAGING MOTION SCAN QUALITY RATING

1 . A method for determining if an object of a scan generated by a movable scanner has moved by comparing images generated at a plurality of orientations of the movable scanner and information related to such images, the method comprising:

scanning the object at a first orientation of the movable scanner;

scanning the object a second time at the first orientation of the movable scanner;

generating a first brightness quantity based on scanning the object at the first orientation;

generating a second brightness quantity based on scanning the object the second time at the first orientation; and

determining a motion factor based on the first brightness quantity, the second brightness quantity and first and second images generated at the first orientation of the movable scanner.

2 . The method of claim 1 , further comprising

comparing the first brightness quantity to the second brightness quantity to determine a delta brightness quantity, and

comparing first and second images to generate a subtraction map, wherein determining the motion factor includes comparing the delta brightness quantity of information related to the subtraction map.

3 . The method of claim 2 , the method further comprising

calculating a plurality of local mean brightness quantities based on a grid related to the subtraction map, and

calculating a plurality of local delta brightness quantities by subtracting the delta brightness quantity from each of the plurality of local mean brightness quantities, wherein determining the motion factor is based on a number of the plurality of local delta brightness quantities.

4 . The method of claim 3 , wherein determining the motion factor includes calculating a standard deviation quantity based on the number of the plurality of local delta brightness quantities.

5 . The method of claim 3 , wherein the number of the plurality of local delta brightness quantities is a predetermined number of the highest local delta brightness quantities.

6 . The method of claim 3 , the method further comprising selecting a natural number corresponding to the number of the plurality of local delta brightness quantities.

7 . The method of claim 6 , wherein the selected number of local delta brightness quantities corresponds to the highest local delta brightness quantities of the plurality of local delta brightness quantities.

8 . The method of claim 3 , subsequent to calculating the plurality of local mean brightness quantities, the method further comprising applying a weighting factor to at least one of the plurality of local mean brightness quantities.

9 . The method of claim 8 , wherein applying the weighting factor includes applying at least one of a first weighting factor related to movement of the movable scanner and a second weighting factor related to movement of the object to the at least one of the plurality of local mean brightness quantities.

10 . The method of claim 9 , wherein the second weighting factor is greater than the first weighting factor.

11 . An apparatus for acquiring tomographic images of an object, the apparatus comprising:

a source of x-rays for directing x-rays to the object;

a detector for sensing the x-rays generated by the source;

a gantry having an axis of rotation for rotating the source and detector about the axis; and

a processor connected to the gantry, source, and detector, the processor controlling

scanning the object at a first orientation of the gantry,

scanning the object a second time at the first orientation of the gantry,

generating a first brightness quantity based on scanning the object at the first orientation,

generating a second brightness quantity based on scanning the object the second time at the first orientation, and

determining a motion factor based on the first brightness quantity, the second brightness quantity and first and second images generated at the first orientation of the gantry.

12 . The apparatus of claim 11 , wherein the processor is further configured to

compare the first brightness quantity to the second brightness quantity to determine a delta brightness quantity, and

compare first and second images to generate a subtraction map.

13 . The apparatus of claim 12 , wherein the processor is further configured to

calculate a plurality of local mean brightness quantities based on a grid related to the subtraction map, and

calculate a plurality of local delta brightness quantities by subtracting the delta brightness quantity from each of the plurality of local mean brightness quantities.

14 . The apparatus of claim 13 , wherein the processor is further configured to determine the motion factor by calculating a standard deviation quantity based on the number of the plurality of local delta brightness quantities.

15 . The apparatus of claim 13 , wherein the processor is further configured to determine a natural number corresponding to the number of the plurality of local delta brightness quantities.

16 . The apparatus of claim 13 , wherein the processor is configured to apply a weighting factor to at least one of the plurality of local mean brightness quantities.

17 . The apparatus of claim 16 , wherein the weighting factor includes at least one of a first weighting factor related to movement of the apparatus and a second weighting factor related to movement of the object.

18 . The apparatus of claim 17 , wherein the second weighting factor is greater than the first weighting factor.