An x-ray based evaluation tool, said tool comprising: a means for measurement of the density of material volumes within and surrounding un-cased, single, dual and multiple-casing wellbore environments, wherein said tool comprises: an internal length comprising a sonde section, wherein said sonde section further comprises an x-ray source; a plurality of axially and azimuthally distributed fixed radiation measuring detectors (202, 203, 302, 410); a radiation shield for radiation measuring detectors; a plurality of sonde-dependent electronics; wherein the tool is designed to use x-rays (201, 301, 408, 504, 508) to illuminate the formation surrounding a borehole, wherein the geometry, movement, and plurality of x-ray source output beams (201, 301, 408, 504, 508) is defined by moveable collimated shielded sleeves (409, 505, 507), wherein the plurality of x-ray source output beams (201, 301, 408, 504, 508) rotated azimuthally around the major axis of the tool interact with the annular materials surrounding the wellbore producing both single and multi-scatter responses, and a plurality of radiation measuring detectors (202, 203, 302, 410) are designed to directly measure the density of the cement annuli and any variations in density within; the single and multi-scatter responses are dependent on the axial offset of the plurality of fixed radiation measuring detectors (202, 203, 302, 410) employed to measure incoming photons resulting from said scatter, wherein said azimuthal plurality of detectors (202, 203, 302, 410) is sampled selectively, such that their output relates specifically to the signal received by the interaction of a single azimuthally rotating x-ray beam, with the annular materials surrounding the wellbore within a single or multi-string cased hole environment, so that a signal or combination of signals for a specific azimuth are recorded and mapped for reproducing a three-dimensional density variation map of the solid angle of interaction of the x-ray source output beam (201, 301, 408, 504, 508) with the annular materials surrounding the wellbore, characterized in that the data collected from each azimuth are compared with neighboring azimuths to ascertain the azimuthal position of an anomaly, such that the two-dimensional maps are amalgamated into a three-dimensional map of the density data for the materials as a function of axial position, azimuthal and radial position. an internal length comprising a sonde section, wherein said sonde section further comprises an x-ray source; a plurality of axially and azimuthally distributed fixed radiation measuring detectors (202, 203, 302, 410); a radiation shield for radiation measuring detectors; a plurality of sonde-dependent electronics; wherein the tool is designed to use x-rays (201, 301, 408, 504, 508) to illuminate the formation surrounding a borehole, wherein the geometry, movement, and plurality of x-ray source output beams (201, 301, 408, 504, 508) is defined by moveable collimated shielded sleeves (409, 505, 507), wherein the plurality of x-ray source output beams (201, 301, 408, 504, 508) rotated azimuthally around the major axis of the tool interact with the annular materials surrounding the wellbore producing both single and multi-scatter responses, and a plurality of radiation measuring detectors (202, 203, 302, 410) are designed to directly measure the density of the cement annuli and any variations in density within; the single and multi-scatter responses are dependent on the axial offset of the plurality of fixed radiation measuring detectors (202, 203, 302, 410) employed to measure incoming photons resulting from said scatter, wherein said azimuthal plurality of detectors (202, 203, 302, 410) is sampled selectively, such that their output relates specifically to the signal received by the interaction of a single azimuthally rotating x-ray beam, with the annular materials surrounding the wellbore within a single or multi-string cased hole environment, so that a signal or combination of signals for a specific azimuth are recorded and mapped for reproducing a three-dimensional density variation map of the solid angle of interaction of the x-ray source output beam (201, 301, 408, 504, 508) with the annular materials surrounding the wellbore, characterized in that the data collected from each azimuth are compared with neighboring azimuths to ascertain the azimuthal position of an anomaly, such that the two-dimensional maps are amalgamated into a three-dimensional map of the density data for the materials as a function of axial position, azimuthal and radial position.