1. A system for analyzing a body to determine the position of elements of different density within said body comprising means to relatively move said body and a density scanning means in a direction along path of travel, said density scanning means including at least one source of electromagnetic energy located adjacent to said path positioned to pass electromagnetic energy through said body in a direction traversing said path as said body and said scanning means are relatively moved and sensor means for said source for sensing the amount of electromagnetic energy passing through said body from said source and generate a scan, said sensor means being composed of a plurality of discrete detectors arranged in circumferential side-by-side relationship relative to said path, each said detector being adapted to detect the amount of radiation received from its respective said source thereby to provide scan line of discrete values indicating density as defined by the degree of attenuation of electromagnetic energy between each said discrete detector and its respective said source and define said scan line formed by a row of pixels extending in a direction representing the direction relative movement of said body and said detector, each said pixel providing a signal depicting density sensed by its respective said detector, said circumferential side by side said detectors in said sensor means forming columns of said pixels in its said scan whereby said scan generated by said sensor means is composed of lines and columns of pixels, filter means for filtering said density signals along each said scan line to provide cleaned signals, characterized by means to define positive peaks in said cleaned signal along said scan lines, and means for plotting said peaks to form an image, means for joining for joining said peaks in adjacent of said scan lines and columns to form a spine image depicting spines of high density areas in said scan.