ASTM E1931 - 09

    Standard Guide for X-Ray Compton Scatter Tomography

    Active Standard ASTM E1931 | Developed by Subcommittee: E07.01

    Book of Standards Volume: 03.03


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    Significance and Use

    Principal Advantage of Compton Scatter TomographyThe principal advantage of CST is the ability to perform three-dimensional X-ray examination without the requirement for access to the back side of the examination object. CST offers the possibility to perform X-ray examination that is not possible by any other method. The CST sub-surface slice image is minimally affected by examination object features outside the plane of examination. The result is a radioscopic image that contains information primarily from the slice plane. Scattered radiation limits image quality in normal radiographic and radioscopic imaging. Scatter radiation does not have the same detrimental effect upon CST because scatter radiation is used to form the image. In fact, the more radiation the examination object scatters, the better the CST result. Low subject contrast materials that cannot be imaged well by conventional radiographic and radioscopic means are often excellent candidates for CST. Very high contrast sensitivities and excellent spatial resolution are possible with CST tomography.

    LimitationsAs with any nondestructive testing method, CST has its limitations. The technique is useful on reasonably thick sections of low-density materials. While a 25 mm (1 in.) depth in aluminum or 50 mm (2 in.) in plastic is achievable, the examination depth is decreased dramatically as the material density increases. Proper image interpretation requires the use of standards and examination objects with known internal conditions or representative quality indicators (RQIs). The examination volume is typically small, on the order of a few cubic inches and may require a few minutes to image. Therefore, completely examining large structures with CST requires intensive re-positioning of the examination volume that can be time-consuming. As with other penetrating radiation methods, the radiation hazard must be properly addressed.

    1. Scope

    1.1 PurposeThis guide covers a tutorial introduction to familiarize the reader with the operational capabilities and limitations inherent in X-ray Compton Scatter Tomography (CST). Also included is a brief description of the physics and typical hardware configuration for CST.

    1.2 AdvantagesX-ray Compton Scatter Tomography (CST) is a radiologic nondestructive examination method with several advantages that include:

    1.2.1 The ability to perform X-ray examination without access to the opposite side of the examination object;

    1.2.2 The X-ray beam need not completely penetrate the examination object allowing thick objects to be partially examined. Thick examination objects become part of the radiation shielding thereby reducing the radiation hazard;

    1.2.3 The ability to examine and image object subsurface features with minimal influence from surface features;

    1.2.4 The ability to obtain high-contrast images from low subject contrast materials that normally produce low-contrast images when using traditional transmitted beam X-ray imaging methods; and

    1.2.5 The ability to obtain depth information of object features thereby providing a three-dimensional examination. The ability to obtain depth information presupposes the use of a highly collimated detector system having a narrow angle of acceptance.

    1.3 ApplicationsThis guide does not specify which examination objects are suitable, or unsuitable, for CST. As with most nondestructive examination techniques, CST is highly application specific thereby requiring the suitability of the method to be first demonstrated in the application laboratory. This guide does not provide guidance in the standardized practice or application of CST techniques. No guidance is provided concerning the acceptance or rejection of examination objects examined with CST.

    1.4 LimitationsAs with all nondestructive examination methods, CST has limitations and is complementary to other NDE methods. Chief among the limitations is the difficulty in performing CST on thick sections of high-Z materials. CST is best applied to thinner sections of lower Z materials. The following provides a general idea of the range of CST applicability when using a 160 keV constant potential X-ray source:

    Material Practical Thickness Range
    SteelUp to about 3 mm (1/8 in.)
    AluminumUp to about 25 mm (1 in.)
    Aerospace compositesUp to about 50 mm (2 in.)
    Polyurethane FoamUp to about 300 mm (12 in.)

    The limitations of the technique must also consider the required X, Y, and Z axis resolutions, the speed of image formation, image quality and the difference in the X-ray scattering characteristics of the parent material and the internal features that are to be imaged.

    1.5 The values stated in both inch-pound and SI units are to be regarded separately as the standard. The values given in parentheses are for information only.

    1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    E747 Practice for Design, Manufacture and Material Grouping Classification of Wire Image Quality Indicators (IQI) Used for Radiology

    E1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image Quality Indicators (IQI) Used for Radiology

    E1255 Practice for Radioscopy

    E1316 Terminology for Nondestructive Examinations

    E1441 Guide for Computed Tomography (CT) Imaging

    E1453 Guide for Storage of Magnetic Tape Media that Contains Analog or Digital Radioscopic Data

    E1475 Guide for Data Fields for Computerized Transfer of Digital Radiological Examination Data

    E1647 Practice for Determining Contrast Sensitivity in Radiology

    ANSI/ASNT Standards

    ANSI/ASNTCP-189 Standard for Qualification and Certification in Nondestructive Testing Personnel

    Military Standard

    MIL-STD-410 Nondestructive Testing Personnel Qualification and Certification Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://www.dodssp.daps.mil.


    ICS Code

    ICS Number Code 35.240.80 (IT applications in health care technology)

    UNSPSC Code

    UNSPSC Code


    DOI: 10.1520/E1931-09

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