![RT Film Making a Radiograph](https://upload.wikimedia.org/wikipedia/commons/2/2a/RT_Film_Making_a_Radiograph.jpg)
Industrial radiography is a modality of
non-destructive testing
Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage.
The terms nondestructive examination (NDE), n ...
that uses
ionizing radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
to inspect materials and components with the objective of locating and quantifying defects and degradation in material properties that would lead to the failure of engineering structures. It plays an important role in the science and technology needed to ensure product quality and reliability. In Australia, industrial radiographic non-destructive testing is colloquially referred to as "bombing" a component with a "bomb".
Industrial Radiography uses either
X-rays
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 Picometre, picometers to 10 Nanometre, nanometers, corresponding to frequency, ...
, produced with
X-ray generator
An X-ray generator is a device that produces X-rays. Together with an X-ray detector, it is commonly used in a variety of applications including medicine, X-ray fluorescence, electronic assembly inspection, and measurement of material thickness ...
s, or
gamma rays
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
generated by the natural
radioactivity of sealed
radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
sources. Neutrons can also be used. After crossing the specimen, photons are captured by a
detector
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
, such as a silver halide film, a
phosphor plate,
flat panel detector
Flat-panel detectors are a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. They are used in both projectional radiography and as an alternative to x-ray ima ...
or
CdTe
Cadmium telluride (CdTe) is a stable crystalline compound formed from cadmium and tellurium. It is mainly used as the semiconducting material in cadmium telluride photovoltaics and an infrared optical window. It is usually sandwiched with cadmi ...
detector. The examination can be performed in static 2D (named
radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...
), in real time 2D (
fluoroscopy
Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and functio ...
), or in 3D after image reconstruction (
computed tomography or CT). It is also possible to perform tomography nearly in real time (
4-dimensionnal computed tomography or 4DCT). Particular techniques such as X-ray fluorescence (
XRF), X-ray diffractometry (
XRD), and several other ones complete the range of tools that can be used in industrial radiography.
Inspection techniques can be portable or stationary. Industrial radiography is used in
welding
Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower ...
,
casting
Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...
parts or
composite
Composite or compositing may refer to:
Materials
* Composite material, a material that is made from several different substances
** Metal matrix composite, composed of metal and other parts
** Cermet, a composite of ceramic and metallic materials
...
pieces inspection, in food inspection and luggage control, in sorting and recycling, in
EOD and
IED analysis,
aircraft maintenance
Aircraft maintenance is the performance of tasks required to ensure the continuing airworthiness of an aircraft or aircraft part, including overhaul, inspection, replacement, defect rectification, and the embodiment of modifications, compliance ...
,
ballistics
Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially ranged weapon munitions such as bullets, unguided bombs, rockets or the like; the science or art of designing and a ...
,
turbine
A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...
inspection, in surface characterisation, coating thickness measurement, in
counterfeit drug
A counterfeit medication or a counterfeit drug is a medication or pharmaceutical item which is produced and sold with the intent to deceptively represent its origin, authenticity, or effectiveness. A counterfeit drug may contain inappropriate qua ...
control, etc.
History
Radiography started in 1895 with the discovery of
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s (later also called
Röntgen rays after the man who first described their properties in detail), a type of
electromagnetic radiation
In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic field, electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, inf ...
. Soon after the discovery of X-rays,
radioactivity was discovered. By using radioactive sources such as
radium
Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather t ...
, far higher
photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always ...
energies could be obtained than those from ''normal''
X-ray generator
An X-ray generator is a device that produces X-rays. Together with an X-ray detector, it is commonly used in a variety of applications including medicine, X-ray fluorescence, electronic assembly inspection, and measurement of material thickness ...
s. Soon these found various applications, with one of the earliest users being
Loughborough College
Loughborough College is a general further education college located in Leicestershire, England which offers a range of courses including further education, higher education, apprenticeships and professional qualifications.
List of princip ...
. X-rays and gamma rays were put to use very early, before the dangers of ionizing radiation were discovered. After
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
new isotopes such as
caesium-137
Caesium-137 (), cesium-137 (US), or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nucl ...
,
iridium-192
There are two natural isotopes of iridium (77Ir), and 34 radioisotopes, the most stable radioisotope being 192Ir with a half-life of 73.83 days, and many nuclear isomers, the most stable of which is 192m2Ir with a half-life of 241 years. All othe ...
and
cobalt-60
Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisoto ...
became available for industrial radiography, and the use of radium and radon decreased.
Applications
Inspection of products
Gamma radiation
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically s ...
sources, most commonly iridium-192 and cobalt-60, are used to inspect a variety of materials. The vast majority of radiography concerns the testing and grading of welds on piping, pressure vessels, high-capacity storage containers, pipelines, and some structural welds. Other tested materials include concrete (locating
rebar
Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a Tension (physics), tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concr ...
or conduit), welder's test
coupons
In marketing, a coupon is a ticket or document that can be redeemed for a financial discount or rebate when purchasing a product.
Customarily, coupons are issued by manufacturers of consumer packaged goods
or by retailers, to be used in r ...
, machined parts, plate metal, or pipewall (locating anomalies due to corrosion or mechanical damage). Non-metal components such as ceramics used in the aerospace industries are also regularly tested. Theoretically, industrial radiographers could radiograph any solid, flat material (walls, ceilings, floors, square or rectangular containers) or any hollow cylindrical or spherical object.
Inspection of welding
The beam of radiation must be directed to the middle of the section under examination and must be normal to the material surface at that point, except in special techniques where known defects are best revealed by a different alignment of the beam. The length of
weld under examination for each exposure shall be such that the thickness of the material at the diagnostic extremities, measured in the direction of the incident beam, does not exceed the actual thickness at that point by more than 6%. The specimen to be inspected is placed between the source of radiation and the detecting device, usually the film in a light tight holder or cassette, and the radiation is allowed to penetrate the part for the required length of time to be adequately recorded.
The result is a two-dimensional projection of the part onto the film, producing a latent image of varying densities according to the amount of
radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
* ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
reaching each area. It is known as a radio graph, as distinct from a photograph produced by light. Because film is cumulative in its response (the exposure increasing as it absorbs more radiation), relatively weak radiation can be detected by prolonging the exposure until the film can record an image that will be visible after development. The radiograph is examined as a
negative, without printing as a positive as in photography. This is because, in printing, some of the detail is always lost and no useful purpose is served.
Before commencing a radiographic examination, it is always advisable to examine the component with one's own eyes, to eliminate any possible external defects. If the surface of a weld is too irregular, it may be desirable to grind it to obtain a smooth finish, but this is likely to be limited to those cases in which the surface irregularities (which will be visible on the radio graph) may make detecting internal defects difficult.
After this visual examination, the operator will have a clear idea of the possibilities of access to the two faces of the weld, which is important both for the setting up of the equipment and for the choice of the most appropriate technique.
Defects such as
delamination
Delamination is a mode of failure where a material fractures into layers. A variety of materials including laminate composites and concrete can fail by delamination. Processing can create layers in materials such as steel formed by rolling a ...
s and
planar
Planar is an adjective meaning "relating to a plane (geometry)".
Planar may also refer to:
Science and technology
* Planar (computer graphics), computer graphics pixel information from several bitplanes
* Planar (transmission line technologies), ...
cracks are difficult to detect using radiography, particularly to the untrained eye.
Without overlooking the negatives of radiographic inspection, radiography does hold many significant benefits over ultrasonics, particularly insomuch that as a 'picture' is produced keeping a semi permanent record for the life cycle of the film, more accurate identification of the defect can be made, and by more interpreters. Very important as most construction standards permit some level of defect acceptance, depending on the type and size of the defect.
To the trained radiographer, subtle variations in visible film density provide the technician the ability to not only accurately locate a defect, but identify its type, size and location; an interpretation that can be physically reviewed and confirmed by others, possibly eliminating the need for expensive and unnecessary repairs.
For purposes of inspection, including
weld inspection
Weld quality assurance is the use of technological methods and actions to test or assure the quality of welds, and secondarily to confirm the presence, location and coverage of welds. In manufacturing, welds are used to join two or more metal surf ...
, there exist several exposure arrangements.
First, there is the panoramic, one of the four single-wall exposure/single-wall view (SWE/SWV) arrangements. This exposure is created when the radiographer places the source of radiation at the center of a sphere, cone, or cylinder (including tanks, vessels, and piping). Depending upon client requirements, the radiographer would then place film cassettes on the outside of the surface to be examined. This exposure arrangement is nearly ideal – when properly arranged and exposed, all portions of all exposed film will be of the same approximate density. It also has the advantage of taking less time than other arrangements since the source must only penetrate the total wall thickness (WT) once and must only travel the radius of the inspection item, not its full diameter. The major disadvantage of the panoramic is that it may be impractical to reach the center of the item (enclosed pipe) or the source may be too weak to perform in this arrangement (large vessels or tanks).
The second SWE/SWV arrangement is an interior placement of the source in an enclosed inspection item without having the source centered up. The source does not come in direct contact with the item, but is placed a distance away, depending on client requirements. The third is an exterior placement with similar characteristics. The fourth is reserved for flat objects, such as plate metal, and is also radiographed without the source coming in direct contact with the item. In each case, the radiographic film is located on the opposite side of the inspection item from the source. In all four cases, only one wall is exposed, and only one wall is viewed on the radiograph.
Of the other exposure arrangements, only the contact shot has the source located on the inspection item. This type of radiograph exposes both walls, but only resolves the image on the wall nearest the film. This exposure arrangement takes more time than a panoramic, as the source must first penetrate the WT twice and travel the entire outside diameter of the pipe or vessel to reach the film on the opposite side. This is a double wall exposure/single wall view DWE/SWV arrangement. Another is the superimposure (wherein the source is placed on one side of the item, not in direct contact with it, with the film on the opposite side). This arrangement is usually reserved for very small diameter piping or parts. The last DWE/SWV exposure arrangement is the elliptical, in which the source is offset from the plane of the inspection item (usually a weld in pipe) and the elliptical image of the weld furthest from the source is cast onto the film.
Airport security
Both hold luggage and carry-on hand luggage are normally examined by
X-ray machine
An X-ray machine is any machine that involves X-rays. It may consist of an X-ray generator and an X-ray detector.
Examples include:
*Machines for medical projectional radiography
*Machines for computed tomography
*Backscatter X-ray machines, used ...
s using X-ray radiography. See
airport security
Airport security includes the techniques and methods used in an attempt to protect passengers, staff, aircraft, and airport property from malicious harm, crime, terrorism, and other threats.
Aviation security is a combination of measures and hum ...
for more details.
Non-intrusive cargo scanning
![VACIS Gamma-ray Image with stowaways](https://upload.wikimedia.org/wikipedia/commons/d/d7/VACIS_Gamma-ray_Image_with_stowaways.GIF)
Gamma radiography and high-energy X-ray radiography are currently used to scan
intermodal freight
Intermodal freight transport involves the transportation of freight in an intermodal container or vehicle, using multiple modes of transportation (e.g., rail, ship, aircraft, and truck), without any handling of the freight itself when changing ...
cargo containers in US and other countries. Also research is being done on adapting other types of radiography like
dual-energy X-ray radiography
Radiography is an imaging technology, imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnos ...
or muon radiography for scanning
intermodal cargo containers.
Art
The American artist
Kathleen Gilje
Kathleen Gilje (born 1945) is an American art restorer and artist. She is best known for her appropriations of Old Master Paintings which combine their historical provenance with contemporary ideas and perspective.
Early life and education
Gilje ...
has painted copies of
Artemisia Gentileschi
Artemisia Lomi or Artemisia Gentileschi (, ; 8 July 1593) was an Italian Baroque painter. Gentileschi is considered among the most accomplished seventeenth-century artists, initially working in the style of Caravaggio. She was producing profess ...
's ''
Susanna and the Elders
Susanna (; : "lily"), also called Susanna and the Elders, is a narrative included in the Book of Daniel (as chapter 13) by the Catholic Church, Oriental Orthodox Churches and Eastern Orthodox Churches. It is one of the additions to Daniel, plac ...
'' and
Gustave Courbet
Jean Désiré Gustave Courbet ( , , ; 10 June 1819 – 31 December 1877) was a French painter who led the Realism movement in 19th-century French painting. Committed to painting only what he could see, he rejected academic convention and t ...
's ''
Woman with a Parrot
''La Femme au perroquet'' (''Woman with a Parrot'') is an oil painting on canvas by French artist Gustave Courbet. It was the first nude by the artist to be accepted by the Paris Salon in 1866 after a previous entry in 1864 was rejected as indec ...
''.
Before, she painted in
lead white
White lead is the basic lead carbonate 2PbCO3·Pb(OH)2. It is a complex salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a hydrate of cerussite. It was ...
similar pictures with differences: Susanna fights the intrusion of the elders;
[*
*] there is a nude Courbet beyond the woman he paints.
Then she painted over reproducing the original.
Gilje's paintings are exhibited with radiographs that show the underpaintings, simulating the study of
pentimento
A pentimento (plural pentimenti), in painting, is "the presence or emergence of earlier images, forms, or strokes that have been changed and painted over". The word is , from the verb , meaning 'to repent'.
Significance
Pentimenti may show that ...
s and providing a comment on the old masters' work.
Sources
Many types of ionizing radiation sources exist for use in industrial radiography.
X-Ray generators
X-ray generator
An X-ray generator is a device that produces X-rays. Together with an X-ray detector, it is commonly used in a variety of applications including medicine, X-ray fluorescence, electronic assembly inspection, and measurement of material thickness ...
s produce
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s by applying a
high voltage
High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant spec ...
between the cathode and the anode of an
X-ray tube
An X-ray tube is a vacuum tube that converts electrical input power into X-rays. The availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast ...
and in heating the tube filament to start the electron emission. The electrons are then accelerated in the resulting
electric potential
The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...
and collide with the anode, which is usually made of
Tungsten
Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...
.
The X-rays that are emitted by this generator are directed towards the object to control. They cross it and are absorbed according to the object material's
attenuation coefficient
The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient valu ...
.
The attenuation coefficient is compiled from all the
cross sections of the interactions that are happening in the material. The three most important inelastic interactions with X-rays at those energy levels are the
photoelectric effect
The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, and solid st ...
,
compton scattering
Compton scattering, discovered by Arthur Holly Compton, is the scattering of a high frequency photon after an interaction with a charged particle, usually an electron. If it results in a decrease in energy (increase in wavelength) of the photon ...
and
pair production
Pair production is the creation of a subatomic particle and its antiparticle from a neutral boson. Examples include creating an electron and a positron, a muon and an antimuon, or a proton and an antiproton. Pair production often refers specific ...
.
After having crossed the object, the photons are captured by a
detector
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
, such as a silver halide film, a
phosphor plate or
flat panel detector
Flat-panel detectors are a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. They are used in both projectional radiography and as an alternative to x-ray ima ...
.
When an object is too thick, too dense, or its
effective atomic number is too high, a
linac
A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear beam ...
can be used. They work in a similar way to produce X-rays, by electron collisions on a metal anode, the difference is that they use a much more complex method to accelerate them.
Sealed Radioactive Sources
Radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
s are often used in industrial radiography. They have the advantage that they do not need a supply of electricity to function, but it also means that they can't be turned off. The two most common radionuclides used in industrial radiography are
Iridium-192
There are two natural isotopes of iridium (77Ir), and 34 radioisotopes, the most stable radioisotope being 192Ir with a half-life of 73.83 days, and many nuclear isomers, the most stable of which is 192m2Ir with a half-life of 241 years. All othe ...
and
Cobalt-60
Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisoto ...
. But others are used in general industry as well.
*
Am-241:
Backscatter gauges,
smoke detectors
A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors are usually housed in plastic enclosures, typically shaped like a disk about in diameter and thick, but shape and size vary. Smoke can be detecte ...
, fill height and ash content detectors.
*
Sr-90: Thickness gauging for thick materials up to 3 mm.
*
Kr-85: Thickness gauging for thin materials like paper, plastics, etc.
*
Cs-137
Caesium-137 (), cesium-137 (US), or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nucl ...
: Density and fill height level switches.
*
Ra-226: Ash content
*
Cf-255: Ash content
*
Ir-192: Industrial radiography
*
Se-75: Industrial radiography
*
Yb-169: Industrial radiography
*
Co-60
Cobalt-60 (60Co) is a synthetic isotope, synthetic radioactive Isotopes of cobalt, isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activat ...
: Density and fill height level switches, industrial radiography
These isotopes emit radiation in a discrete set of energies, depending on the
decay
Decay may refer to:
Science and technology
* Bit decay, in computing
* Software decay, in computing
* Distance decay, in geography
* Decay time (fall time), in electronics
Biology
* Decomposition of organic matter
* Tooth decay (dental caries ...
mechanism happening in the
atomic nucleus
The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron i ...
. Each energies will have different intensities depending on the probability of a particular decay interaction. The most prominent energies in Cobalt-60 are 1.33 and 1.17 MeV, and 0.31, 0.47 and 0.60 MeV for Iridium-192. From a
radiation safety
Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Expos ...
point of view, this makes them more difficult to handle and manage. They always need to be enclosed in a shielded container and because they are still radioactive after their normal life cycle, their ownership often requires a license and they are usually tracked by a governmental body. If this is the case, their disposal must be done in accordance with the national policies.
The radionuclides used in industrial radiography are chosen for their high
specific activity
Specific activity is the activity per unit mass of a radionuclide and is a physical property of that radionuclide.
Activity is a quantity (for which the SI unit is the becquerel) related to radioactivity, and is defined as the number of radi ...
. This high activity means that only a small sample is required to obtain a good radiation flux. However, higher activity often means higher dose in the case of an accidental exposure.
Radiographic cameras
A series of different designs have been developed for radiographic "cameras". Rather than the "camera" being a device that accepts photons to record a picture, the "camera" in industrial radiography is the radioactive photon source. Most industries are moving from film based radiography to a digital sensor based radiography much the same way that traditional photography has made this move.
Since the amount of radiation emerging from the opposite side of the material can be detected and measured, variations in this amount (or intensity) of radiation are used to determine thickness or composition of material.
= Shutter design
=
One design uses a moving shutter to expose the source. The radioactive source is placed inside a shielded box, a hinge allows part of the shielding to be opened exposing the source, allowing photons to exit the radiography camera.
![Torchradiographycamerawithhinge](https://upload.wikimedia.org/wikipedia/commons/c/ca/Torchradiographycamerawithhinge.png)
Another design for a shutter is where the source is placed in a metal wheel, which can turn inside the camera to move between the expose and storage positions.
![Wheelradiographymachine](https://upload.wikimedia.org/wikipedia/commons/9/98/Wheelradiographymachine.png)
Shutter-based devices require the entire device, including the heavy shielding, to be located at the exposure site. This can be difficult or impossible, so they have largely been replaced by cable-driven projectors.
= Projector design
=
Modern projector designs use a cable drive mechanism to move the source along a hollow guide tube to the exposure location. The source is stored in a block of shielding that has an S-shaped tube-like hole through the block. In the safe position the source is in the center of the block. The source is attached to a flexible metal cable called a pigtail. To use the source a guide tube is attached to one side of the device while a drive cable is attached to the pigtail. Using a hand-operated control the source is then pushed out of the shield and along the source guide tube to the tip of the tube to expose the film, then cranked back into its fully shielded position.
Neutrons
In some rare cases, radiography is done with
neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
s. This type of radiography is called
neutron radiography
Neutron imaging is the process of making an image with neutrons. The resulting image is based on the neutron attenuation properties of the imaged object. The resulting images have much in common with industrial X-ray images, but since the image i ...
(NR, Nray, N-ray) or
neutron imaging
Neutron imaging is the process of making an image with neutrons. The resulting image is based on the neutron attenuation properties of the imaged object. The resulting images have much in common with industrial X-ray images, but since the image i ...
. Neutron radiography provides different images than X-rays, because neutrons can pass with ease through lead and steel but are stopped by plastics, water and oils. Neutron sources include radioactive (
241Am/Be and Cf) sources, electrically driven D-T reactions in vacuum tubes and conventional critical nuclear reactors. It might be possible to use a neutron amplifier to increase the neutron flux.
Safety
Radiation safety is a very important part of industrial radiography. The
International Atomic Energy Agency
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 1957 ...
has published a report describing the best practices in order to lower the amount of
radiation dose
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
the workers are exposed to. It also provides a list of national competent authorities responsible for approvals and authorizations regarding the handling of radioactive material.
Shielding
Shielding can be used to protect the user of the
harmful properties of ionizing radiation. The type of material used for shielding depends on the type of radiation being used. National radiation safety authorities usually regulate the design, commissioning, maintenance and inspection of Industrial Radiography installations.
In the industry
Industrial radiographers are in many locations required by governing authorities to use certain types of safety equipment and to work in pairs. Depending on location industrial radiographers may have been required to obtain permits, licenses and/or undertake special training. Prior to conducting any testing the nearby area should always first be cleared of all other persons and measures should be taken to ensure that workers do not accidentally enter into an area that may expose them to dangerous levels of radiation.
The safety equipment usually includes four basic items: a radiation survey meter (such as a Geiger/Mueller counter), an alarming dosimeter or rate meter, a gas-charged dosimeter, and a film badge or thermoluminescent dosimeter (TLD). The easiest way to remember what each of these items does is to compare them to gauges on an automobile.
The survey meter could be compared to the speedometer, as it measures the speed, or rate, at which radiation is being picked up. When properly calibrated, used, and maintained, it allows the radiographer to see the current exposure to radiation at the meter. It can usually be set for different intensities, and is used to prevent the radiographer from being overexposed to the radioactive source, as well as for verifying the boundary that radiographers are required to maintain around the exposed source during radiographic operations.
The alarming dosimeter could be most closely compared with the tachometer, as it alarms when the radiographer "redlines" or is exposed to too much radiation. When properly calibrated, activated, and worn on the radiographer's person, it will emit an alarm when the meter measures a radiation level in excess of a preset threshold. This device is intended to prevent the radiographer from inadvertently walking up on an exposed source.
The gas-charged dosimeter is like a trip meter in that it measures the total radiation received, but can be reset. It is designed to help the radiographer measure his/her total periodic dose of radiation. When properly calibrated, recharged, and worn on the radiographer's person, it can tell the radiographer at a glance how much radiation to which the device has been exposed since it was last recharged. Radiographers in many states are required to log their radiation exposures and generate an exposure report. In many countries personal dosimeters are not required to be used by radiographers as the dose rates they show are not always correctly recorded.
The film badge or TLD is more like a car's odometer. It is actually a specialized piece of radiographic film in a rugged container. It is meant to measure the radiographer's total exposure over time (usually a month) and is used by regulating authorities to monitor the total exposure of certified radiographers in a certain jurisdiction. At the end of the month, the film badge is turned in and is processed. A report of the radiographer's total dose is generated and is kept on file.
When these safety devices are properly calibrated, maintained, and used, it is virtually impossible for a radiographer to be injured by a radioactive overexposure. The elimination of just one of these devices can jeopardize the safety of the radiographer and all those who are nearby. Without the survey meter, the radiation received may be just below the threshold of the rate alarm, and it may be several hours before the radiographer checks the dosimeter, and up to a month or more before the film badge is developed to detect a low intensity overexposure. Without the rate alarm, one radiographer may inadvertently walk up on the source exposed by the other radiographer. Without the dosimeter, the radiographer may be unaware of an overexposure, or even a radiation burn, which may take weeks to result in noticeable injury. And without the film badge, the radiographer is deprived of an important tool designed to protect him or her from the effects of a long-term overexposure to occupationally obtained radiation, and thus may suffer long-term health problems as a result.
There are three ways a radiographer will ensure they are not exposed to higher than required levels of radiation, time, distance, shielding. The less time that a person is exposed to radiation the lower their dose will be. The further a person is from a radioactive source the lower the level of radiation they receive, this is largely due to the inverse square law. Lastly the more a radioactive source is shielded by either better or greater amounts of shielding the lower the levels of radiation that will escape from the testing area. The most commonly used shielding materials in use are sand, lead (sheets or shot), steel, spent (non-radioactive uranium) tungsten and in suitable situations water.
Industrial radiography appears to have one of the worst safety profiles of the radiation professions, possibly because there are many operators using strong
gamma
Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...
sources (> 2 Ci) in remote sites with little supervision when compared with workers within the
nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
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*Nuclear power
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*Nuclear weapon
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*Nuclear ...
industry or within hospitals. Due to the levels of radiation present whilst they are working many radiographers are also required to work late at night when there are few other people present as most industrial radiography is carried out 'in the open' rather than in purpose built exposure booths or rooms. Fatigue, carelessness and lack of proper training are the three most common factors attributed to industrial radiography accidents. Many of the "lost source" accidents commented on by the
International Atomic Energy Agency
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 1957 ...
involve radiography equipment. Lost source accidents have the potential to cause a considerable loss of human life. One scenario is that a passerby finds the radiography source and not knowing what it is, takes it home. The person shortly afterwards becomes ill and dies as a result of the radiation dose. The source remains in their home where it continues to irradiate other members of the household.
[Alain Bia]
Radiation protection of the workers in industrial radiography: the point of view of the regulatory body in France
Office de Protection contre les Rayonnements Ionisants Such an event occurred in March 1984 in
Casablanca
Casablanca, also known in Arabic as Dar al-Bayda ( ar, الدَّار الْبَيْضَاء, al-Dār al-Bayḍāʾ, ; ber, ⴹⴹⴰⵕⵍⴱⵉⴹⴰ, ḍḍaṛlbiḍa, : "White House") is the largest city in Morocco and the country's econom ...
,
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
. This is related to the more famous
Goiânia accident
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, in Goiânia, Goiás, Brazil, after a forgotten radiotherapy source was stolen from an abandoned hospital site in the city. It was subsequent ...
, where a related chain of events caused members of the public to be exposed to radiation sources.
List of standards
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Ar ...
(ISO)
* ISO 4993, ''Steel and iron castings – Radiographic inspection''
* ISO 5579, ''Non-destructive testing – Radiographic examination of metallic materials by X- and gamma-rays – Basic rules''
* ISO 10675-1, ''Non-destructive testing of welds – Acceptance levels for radiographic testing – Part 1: Steel, nickel, titanium and their alloys''
* ISO 11699-1, ''Non-destructive testing – Industrial radiographic films – Part 1: Classification of film systems for industrial radiography''
* ISO 11699-2, ''Non-destructive testing – Industrial radiographic films – Part 2: Control of film processing by means of reference values''
* ISO 14096-1, ''Non-destructive testing – Qualification of radiographic film digitisation systems – Part 1: Definitions, quantitative measurements of image quality parameters, standard reference film and qualitative control''
* ISO 14096-2, ''Non-destructive testing – Qualification of radiographic film digitisation systems – Part 2: Minimum requirements''
* ISO 17636-1: ''Non-destructive testing of welds. Radiographic testing. X- and gamma-ray techniques with film''
* ISO 17636-2: ''Non-destructive testing of welds. Radiographic testing. X- and gamma-ray techniques with digital detectors''
* ISO 19232, ''Non-destructive testing – Image quality of radiographs''
European Committee for Standardization
The European Committee for Standardization (CEN, french: Comité Européen de Normalisation) is a public standards organization whose mission is to foster the economy of the European Single Market and the wider European continent in global tr ...
(CEN)
* EN 444, ''Non-destructive testing; general principles for the radiographic examination of metallic materials using X-rays and gamma-rays''
* EN 462-1: ''Non-destructive testing – image quality of radiographs – Part 1: Image quality indicators (wire type) – determination of image quality value''
* EN 462-2, ''Non-destructive testing – image quality of radiographs – Part 2: image quality indicators (step/hole type) determination of image quality value''
* EN 462-3, ''Non-destructive testing – Image quality of radiogrammes – Part 3: Image quality classes for ferrous metals''
* EN 462-4, ''Non-destructive testing – Image quality of radiographs – Part 4: Experimental evaluation of image quality values and image quality tables''
* EN 462-5, ''Non-destructive testing – Image quality of radiographs – Part 5: Image quality of indicators (duplex wire type), determination of image
unsharpness
Unsharpness is the loss of spatial resolution in a Radiography, radiographic image. There are generally considered to be three types of unsharpness: geometric unsharpness, motion unsharpness and photographic or system unsharpness.
Motion unsharpn ...
value''
* EN 584-1, ''Non-destructive testing – Industrial radiographic film – Part 1: Classification of film systems for industrial radiography''
* EN 584-2, ''Non-destructive testing – Industrial radiographic film – Part 2: Control of film processing by means of reference values''
* EN 1330-3, ''Non-destructive testing – Terminology – Part 3: Terms used in industrial radiographic testing''
* EN 2002–21, ''Aerospace series – Metallic materials; test methods – Part 21: Radiographic testing of castings''
* EN 10246-10, ''Non-destructive testing of steel tubes – Part 10: Radiographic testing of the weld seam of automatic fusion arc welded steel tubes for the detection of imperfections''
* EN 12517-1, ''Non-destructive testing of welds – Part 1: Evaluation of welded joints in steel, nickel, titanium and their alloys by radiography – Acceptance levels''
* EN 12517-2, ''Non-destructive testing of welds – Part 2: Evaluation of welded joints in aluminium and its alloys by radiography – Acceptance levels''
* EN 12679, ''Non-destructive testing – Determination of the size of industrial radiographic sources – Radiographic method''
* EN 12681, ''Founding – Radiographic examination''
* EN 13068, ''Non-destructive testing – Radioscopic testing''
* EN 14096, ''Non-destructive testing – Qualification of radiographic film digitisation systems''
* EN 14784-1, ''Non-destructive testing – Industrial computed radiography with storage phosphor imaging plates – Part 1: Classification of systems''
* EN 14584-2, ''Non-destructive testing – Industrial computed radiography with storage phosphor imaging plates – Part 2: General principles for testing of metallic materials using X-rays and gamma rays''
ASTM International
ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, ...
(ASTM)
* ASTM E 94, ''Standard Guide for Radiographic Examination''
* ASTM E 155, ''Standard Reference Radiographs for Inspection of Aluminum and Magnesium Castings''
* ASTM E 592, ''Standard Guide to Obtainable ASTM Equivalent Penetrameter Sensitivity for Radiography of Steel Plates 1/4 to 2 in.
to 51 mmThick with X Rays and 1 to 6 in.
5 to 152 mmThick with Cobalt-60''
* ASTM E 747, ''Standard Practice for Design, Manufacture and Material Grouping Classification of Wire Image Quality Indicators (IQI) Used for Radiology''
* ASTM E 801, ''Standard Practice for Controlling Quality of Radiological Examination of Electronic Devices''
* ASTM E 1030, ''Standard Test Method for Radiographic Examination of Metallic Castings''
* ASTM E 1032, ''Standard Test Method for Radiographic Examination of Weldments''
* ASTM 1161, ''Standard Practice for Radiologic Examination of Semiconductors and Electronic Components''
* ASTM E 1648, ''Standard Reference Radiographs for Examination of Aluminum Fusion Welds''
* ASTM E 1735, ''Standard Test Method for Determining Relative Image Quality of Industrial Radiographic Film Exposed to X-Radiation from 4 to 25 MeV''
* ASTM E 1815, ''Standard Test Method for Classification of Film Systems for Industrial Radiography''
* ASTM E 1817, ''Standard Practice for Controlling Quality of Radiological Examination by Using Representative Quality Indicators (RQIs)''
* ASTM E 2104, ''Standard Practice for Radiographic Examination of Advanced Aero and Turbine Materials and Components''
American Society of Mechanical Engineers
The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing ...
(ASME)
*
BPVC Section V, ''Nondestructive Examination: Article 2 Radiographic Examination''
American Petroleum Institute
The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in production, refinement, distribution, and many other aspects of the pet ...
(API)
* API 1104, ''Welding of Pipelines and Related Facilities: 11.1 Radiographic Test Methods''
See also
*
Collimator
A collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spati ...
*
Industrial computed tomography
Industrial computed tomography (CT) scanning is any computer-aided tomographic process, usually X-ray computed tomography, that uses irradiation to produce three-dimensional internal and external representations of a scanned object. Industrial CT ...
*
Medical radiography
Notes
References
External links
NIST's XAAMDI: X-Ray Attenuation and Absorption for Materials of Dosimetric Interest DatabaseList of incidents
{{Authority control
Nondestructive testing
Radiography
Casting (manufacturing)
Welding