ASTM E1000-98
(Guide)Standard Guide for Radioscopy
Standard Guide for Radioscopy
SCOPE
1.1 This guide is for tutorial purposes only and to outline the general principles of radioscopic imaging.
1.2 This guide describes practices and image quality measuring systems for real-time, and near real-time, nonfilm detection, display, and recording of radioscopic images. These images, used in materials inspection, are generated by penetrating radiation passing through the subject material and producing an image on the detecting medium. Although the described radiation sources are specifically X-ray and gamma-ray, the general concepts can be used for other radiation sources such as neutrons. The image detection and display techniques are nonfilm, but the use of photographic film as a means for permanent recording of the image is not precluded. Note-For information purposes, refer to Terminology E1316.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific safety precautionary statements, see Section 7.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
An American National Standard
Designation: E 1000 – 98
Standard Guide for
Radioscopy
This standard is issued under the fixed designation E 1000; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Medical Use of X Rays and Gamma Rays of Energies up
to 10 MeV
1.1 This guide is for tutorial purposes only and to outline the
NCRP 51 Radiation Protection Design Guidelines for
general principles of radioscopic imaging.
0.1–100 MeV Particle Accelerator Facilities
1.2 This guide describes practices and image quality mea-
NCRP 91, (supercedes NCRP 39) Recommendations on
suring systems for real-time, and near real-time, nonfilm
Limits for Exposure to Ionizing Radiation
detection, display, and recording of radioscopic images. These
2.3 Federal Standard:
images, used in materials inspection, are generated by penetrat-
Fed. Std. No. 21-CFR 1020.40 Safety Requirements for
ing radiation passing through the subject material and produc-
Cabinet X-Ray Machines
ing an image on the detecting medium. Although the described
radiation sources are specifically X-ray and gamma-ray, the
3. Summary of Guide
general concepts can be used for other radiation sources such
3.1 This guide outlines the practices for the use of radio-
as neutrons. The image detection and display techniques are
scopic methods and techniques for materials examinations. It is
nonfilm, but the use of photographic film as a means for
intended to provide a basic understanding of the method and
permanent recording of the image is not precluded.
the techniques involved. The selection of an imaging device,
NOTE 1—For information purposes, refer to Terminology E 1316.
radiation source, and radiological and optical techniques to
1.3 This standard does not purport to address all of the achieve a specified quality in radioscopic images is described.
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 Radioscopy is a versatile nondestructive means for
priate safety and health practices and determine the applica-
examining an object. It provides immediate information re-
bility of regulatory limitations prior to use. For specific safety
garding the nature, size, location, and distribution of imperfec-
precautionary statements, see Section 6.
tions, both internal and external. It also provides a rapid check
2. Referenced Documents
of the dimensions, mechanical configuration, and the presence
and positioning of components in a mechanism. It indicates in
2.1 ASTM Standards:
E 142 Method for Controlling Quality of Radiographic real-time the presence of structural or component imperfec-
tions anywhere in a mechanism or an assembly. Through
Testing
E 747 Practice for Design, Manufacture and Material manipulation, it may provide three-dimensional information
Grouping Classification of Wire Image Quality Indicators regarding the nature, sizes, and relative positioning of items of
interest within an object, and can be further employed to check
(IQI) Used for Radiology
E 1025 Practice for Design, Manufacture, and Material the functioning of internal mechanisms. Radioscopy permits
timely assessments of product integrity, and allows prompt
Grouping Classification of Hole-Type Image Quality Indi-
cators (IQI) Used for Radiology disposition of the product based on acceptance standards.
Although closely related to the radiographic method, it has
E 1316 Terminology for Nondestructive Examinations
2.2 National Council on Radiation Protection and Mea- much lower operating costs in terms of time, manpower, and
material.
surement (NCRP) Standards:
NCRP 49 Structural Shielding Design and Evaluation for 4.2 Long-term records of the radioscopic image may be
obtained through motion-picture recording (cinefluorography),
video recording, or “still” photographs using conventional
This guide is under the jurisdiction of ASTM Committee E-7 on Nondestructive
Testing and is the direct responsibility of Subcommittee E07.01 on Radiology (X
and Gamma) Method.
Available from NCRP Publications, 7010 Woodmont Ave., Suite 1016, Be-
Current edition approved May 10, 1998. Published July 1998. Originally
thesda, MD 20814.
published as E 1000 – 89. Last previous edition E 1000 – 92(1996).
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Annual Book of ASTM Standards, Vol 03.03.
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1000
cameras. The radioscopic image may be electronically en- electron conduction (SEC) vidicon, and the advent of ad-
hanced, digitized, or otherwise processed for improved visual vanced, low-noise video circuitry have made it possible to use
image analysis or automatic, computer-aided analysis, or both. television cameras to scan conventional, high-resolution, low-
light-output fluorescent screens directly. The results are com-
5. Background
parable to those obtained with the image intensifier.
5.1 Fluorescence was the means by which X rays were
5.3 In recent years new digital radiology techniques have
discovered, but industrial fluoroscopy began some years later
been developed. These methods produce directly digitized
with the development of more powerful radiation sources and
representations of the X-ray field transmitted by a test article.
improved screens. Fluoroscopic screens typically consist of
Direct digitization enhances the signal-to-noise ratio of the data
phosphors that are deposited on a substrate. They emit light in
and presents the information in a form directly suitable for
proportion to incident radiation intensity, and as a function of
electronic image processing and enhancement, and storage on
the composition, thickness, and grain size of the phosphor
magnetic tape. Digital radioscopic systems use scintillator-
coating. Screen brightness is also a function of the wavelength
photodetector and phosphor-photodetector sensors in flying
of the impinging radiation. Screens with coarse-grained or
spot and fan beam-detector array arrangements.
thick coatings of phosphor, or both, are usually brighter but
5.4 All of these techniques employ television presentation
have lower resolution than those with fine grains or thin
and can utilize various electronic techniques for image en-
coatings, or both. In the past, conventional fluorescent screens
hancement, image storage, and video recording. These ad-
limited the industrial applications of fluoroscopy. The light
vanced imaging devices, along with modern video processing
output of suitable screens was quite low (on the order of 0.1
and analysis techniques, have greatly expanded the versatility
−3 2
millilambert or 0.343 3 10 cd/m ) and required about 30 min
of radioscopic imaging. Industrial applications have become
for an examiner to adapt his eyes to the dim image. To protect
wide-spread: production examination of the longitudinal fusion
the examiner from radiation, the fluoroscopic image had to be
welds in line pipe, welds in rocket-motor housings, castings,
viewed through leaded glass or indirectly using mirror optics.
transistors, microcircuits, circuit-boards rocket propellant uni-
Such systems were used primarily for the examination of
formity, solenoid valves, fuses, relays, tires and reinforced
light-alloy castings, the detection of foreign material in food-
plastics are typical examples.
stuffs, cotton and wool, package inspection, and checking
5.5 Limitations—Despite the numerous advances in RRTI
weldments in thin or low-density metal sections. The choice of
technology, the sensitivity and resolution of real-time systems
fluoroscopy over radiography was generally justified where
usually are not as good as can be obtained with film. In
time and cost factors were important and other nondestructive
radioscopy the time exposures and close contact between the
methods were not feasible.
film and the subject, the control of scatter, and the use of
5.2 It was not until the early 1950’s that technological
screens make it relatively simple to obtain better than 2 %
advances set the stage for widespread uses of industrial
penetrameter sensitivity in most cases. Inherently, because of
fluoroscopy. The development of the X-ray image intensifier
statistical limitations dynamic scenes require a higher X-ray
provided the greatest impetus. It had sufficient brightness gain
flux level to develop a suitable image than static scenes. In
to bring fluoroscopic images to levels where examination could
addition, the product-handling considerations in a dynamic
be performed in rooms with somewhat subdued lighting, and
imaging system mandate that the image plane be separated
without the need for dark adaption. These intensifiers con-
from the surface of the product resulting in perceptible image
tained an input phosphor to convert the X rays to light, a
unsharpness. Geometric unsharpness can be minimized by
photocathode (in intimate contact with the input phosphor) to
employing small focal spot (fractions of a millimetre) X-ray
convert the light image into an electronic image, electron
sources, but this requirement is contrary to the need for the
accelerating and focusing electrodes, and a small output
high X-ray flux density cited previously. Furthermore, limita-
phosphor. Intensifier brightness gain results from both the ratio
tions imposed by the dynamic system make control of scatter
of input to output phosphor areas and the energy imparted to
and geometry more difficult than in conventional radiographic
the electrons. Early units had brightness gains of around 1200
systems. Finally, dynamic radioscopic systems require careful
to 1500 and resolutions somewhat less than high-resolution
alignment of the source, subject, and detector and often
conventional screens. Modern units utilizing improved phos-
expensive product-handling mechanisms. These, along with
phors and electronics have brightness gains in excess of
the radiation safety requirements peculiar to dynamic systems
10 0003 and improved resolution. For example, welds in steel
usually result in capital equipment costs considerably in excess
thicknesses up to 28.6 mm (1.125 in.) can be examined at 2 %
of that for conventional radiography. The costs of expendables,
plaque penetrameter sensitivity using a 160 constant potential
manpower, product-handling and time, however, are usually
X-ray generator (kVcp) source. Concurrent with image-
significantly lower for radioscopic systems.
intensifier developments, direct X ray to television-camera
6. Safety Precautions
tubes capable of high sensitivity and resolution on low-density
materials were marketed. Because they require a comparatively 6.1 The safety procedures for the handling and use of
high X-ray flux input for proper operation, however, their use ionizing radiation sources must be followed. Mandatory rules
has been limited to examination of low-density electronic and regulations are published by governmental licensing agen-
components, circuit boards, and similar applications. The cies, and guidelines for control of radiation are available in
development of low-light level television (LLLTV) camera publications such as the Fed. Std. No. 21-CFR 1020.40.
tubes, such as the isocon, intensifier orthicon, and secondary Careful radiation surveys should be made in accordance with
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 1000
regulations and codes and should be conducted in the exami- portional to the original X-ray photon and can be utilized in a
nation area as well as adjacent areas under all possible variety of ways to produce images, including the following
operating conditions. useful processes.
8.4.1 Energizing of Semiconductor Junctions—The resis-
7. Interpretation and Reference Standards
tance of a semiconductor, or of a semiconductor junction in a
7.1 Reference radiographs produced by ASTM and accep- device such as a diode or transistor, can be altered by adding
tance standards written by other organizations may be em-
free electrons. The energy of an X-ray photon is capable of
ployed for radioscopic inspection as well as for radiography,
freeing electrons in such materials and can profoundly affect
provided appropriate adjustments are made to accommodate
the operation of the device. For example, a simple silicon
for the differences in the fluoroscopic images.
“solar cell” connected to a microammeter will produce a
substantial current when exposed to an X-ray source.
8. Radioscopic Devices, Classification
8.4.1.1 If an array of small semiconductor devices is ex-
8.1 The most commonly used electromagnetic radiation in
posed to an X-ray beam, and the performance of each device is
radioscopy is produced by X-ray sources. X rays are affected in
sampled, then an image can be produced by a suitable display
various modes and degrees by passage through matter. This
of the data. Such arrays can be linear or two-dimensional.
provides very useful information about the matter that has been
Linear arrays normally require relative motion between the
traversed. The detection of these X-ray photons in such a way
object and the array to produce a useful real-time image. The
that the information they carry can be used immediately is the
choice depends upon the application.
prime requisite of radioscopy. Since there are many ways of
8.4.2 Affecting Resistance of Semiconductors—The most
detecting the presence of X rays, their energy and flux density,
common example of this is the X-ray sensitive vidicon camera
there are a number of possible systems. Of these, only a few
tube. Here the target layer of the vidicon tube, and its support,
deserve more than the attention caused by scientific curiosity.
are modified to have an improved sensitivity to X-ray photons.
For our purposes here, only these few are classified and
The result is a change in conductivity of the target layer
described.
corresponding to the pattern of X-ray flux falling upon the
8.2 Basic Classification of Radioscopic Systems—All com-
tube, and this is directly transformed by the scanning beam into
monly used systems depend on two basic p
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