a system and method for accurately reconstructing an image of a roi within a long object by removing components associated with data contamination . in one aspect , an image reconstruction method comprises collecting a set of image data along a spiral scan path of a roi portion of an object , identifying contaminated data within the collected set of image data , the contaminated data corresponding to image data associated with an object outside the roi , and reconstructing an image of the roi using the set of image data less the contaminated data .