GB2129160A - Image quality indicators for radiographic techniques - Google Patents
Image quality indicators for radiographic techniques Download PDFInfo
- Publication number
- GB2129160A GB2129160A GB08327909A GB8327909A GB2129160A GB 2129160 A GB2129160 A GB 2129160A GB 08327909 A GB08327909 A GB 08327909A GB 8327909 A GB8327909 A GB 8327909A GB 2129160 A GB2129160 A GB 2129160A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radiation
- image quality
- quality indicator
- regions
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 16
- 230000005855 radiation Effects 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 26
- 239000000758 substrate Substances 0.000 claims abstract description 15
- 239000000839 emulsion Substances 0.000 claims abstract description 4
- 206010073306 Exposure to radiation Diseases 0.000 claims abstract description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000007769 metal material Substances 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- 238000012545 processing Methods 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 abstract description 4
- 239000004332 silver Substances 0.000 abstract description 4
- -1 silver halide Chemical class 0.000 abstract 1
- 230000035945 sensitivity Effects 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- 239000004411 aluminium Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000002601 radiography Methods 0.000 description 1
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/16—X-ray, infrared, or ultraviolet ray processes
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/02—Sensitometric processes, e.g. determining sensitivity, colour sensitivity, gradation, graininess, density; Making sensitometric wedges
Abstract
An image quality indicator 20 comprises a substrate of material substantially transparent to radiation and a series of regions 21 coated with an absorptive material, each region having a respective predetermined absorptivity, whereby on exposure to radiation, each region passes a respective amount of said radiation. The indicator is preferably prepared photographically using a silver halide emulsion and is used to assess image quality when examining specimens, eg of Al sheet with X-rays. <IMAGE>
Description
SPECIFICATION
Image quality indicators for radiographic techniques
This invention relates to image quality indicators.
An image quality indicator (IQI) is a device by which the quality of a radiographic technique can be assessed. It enables the achievement of optimum conditions in technique preparation~ for example, the type of radiograph film used, the intensity and wavelength of the radiation source, the parameters of the developing and fixing-and allows monitoring of the quality level of successive radiographs. The use of image quality indicators is normally mandatory for most radiographic inspection purposes.
The IQI (or "penetrameter" in U.S.A.
terminology) has in the past been made in the form of steps, wires or plaques of varying thickness and of the same or similar material to that of the specimen to be radiographed. Prior to exposure the IQI is placed on the radiation source side of the specimen or on a block arranged adjacent to the specimen of similar material and thickness to those of the specimen, so that the exposed radiograph includes a latent image of the
IQI superimposed on the specimen. The quality of the exposed, developed and fixed radiograph of the specimen is then assessed visually in terms of the thickness of the thinnest step, wire or plaque of the IQI discernible against the specimen on the radiograph.The image quality indicator sensitivity (IQI sensitivity) is arrived at by expressing the thickness of the thinnest step, wire or plaque visible on the radiograph as a percentage of the thickness of the specimen. The usual IQI sensitivity required for most radiographic techniques is 2% or less.
Although a direct relationship does not exist between the 101 sensitivity and the size of the smallest flaw visible on the radiograph, there is a complex relationship between the two. The 101 sensitivity is, however, useful to ensure the maintenance of quality of a series of radiographs and to establish a standard.
Since the steps of the 101 must be in the order of 2% of the thickness of the specimen to be tested, so that an 101 sensitivity of 2% or less may be determined, the thickness of specimen to which the technique can be applied is limited by the thinnest step or wire which can practically be produced. For example, the useful range of thickness of aluminium specimens of which the 101 sensitivity may be measured is limited at the lower end to a thickness of 6 mm or 0.25" of aluminium. This is due to the fact that it is impractical to produce steps, wires or plaques thinner than 0.1 mm or 0.005".
In the aircraft industry, it may be required to test an aluminium component-for example, an aircraft skin-which has a thickness considerably less than 6 mm. or 0.25". Consequently, it is not presently possible readily to determine the 101 sensitivity in such cases, and thus a good proportion of aircraft radiography falls below the useful range of currently available IOl's.
Moreover, the increased use of carbon fibre composite structures with a radiographic requirement has created a need for an IQI suitable for use in lower kilo-voltage ranges. A suitable 101 for carbon fibre composites presents difficulties on two counts, namely the material is relatively transparent to X-ray radiation and its composite nature makes it unsuitable for the extremely fine sections that would be required for a parent material 101.
According to one aspect of this invention, there is provided an image quality indicator, which comprises a substrate of material substantially transparent to radiation having a plurality of regions coated with a material absorptive to radiation, each of said regions having a respective predetermined absorptivity whereby on exposure to radiation, each region passes a respective amount of radiation.
Preferably, each region is spaced from neighbouring regions to provide interstices which are substantially transparent to radiation.
Preferably the substrate includes indicia provided on the substrate adjacent each of said regions.
For the purposes of assessing the resolution of an image, it is advantageous for the substrate further to comprise uniformly coated regions provided on the substrate and spaced apart to define a parallel-sided gap of predetermined thickness which is substantially transparent to radiation.
Preferably, the substrate is of plastics material and the radiation absorptive material comprises particulate metallic material.
In another aspect of this invention, there is provided a method of manufacturing an image quality indicator which comprises the steps of
(i) selecting a photographic film comprising a
substrate of material substantially
transparent to radiation having provided
on a surface thereof a photo-sensitive
emulsion,
(ii) exposing selected regions of said film to
respective amounts of radiation,
(iii) processing said film to provide a plurality
of selected regions each coated with a
material absorptive to radiation and each
having a respective absorptivity.
By way of example only, one specific embodiment of image quality indicator will now be described in detail, reference being made to the accompanying drawings, in which:
Figure 1 is a representation of one embodiment of image quality indicator of this invention, and
Figure 2 is a schematic representation of a radiographic technique employing the image quality indicator of Fgure 1.
Referring to Figure 1, the image quality indicator 20 comprises a strip of sheet material substantially transparent to X-ray radiation having ten square regions 21 thereon and adjacent
indicia 1 to 10 identifying each region. Each
region has provided thereon a uniform coating of
metallic silver particles, the density of the regions
progressively increasing from a relatively low
density (square 1) to a relatively high density
(square 10), the actual density of each square
being tabulated elsewhere. It will be apparent that the density or opacity of each region is related to the amount of radiation absorbed thereby on exposure to a radiation source. An emblem 22 comprised of a number of sharply defined regions coated with metallic silver particles and defining
gaps 23. 24 of known width.For example, the gaps may be in the range of from 0.5 mm. to 0.25 mm. The base 25 of the emblem is composed of bar-shaped regions 26 of progressively increasing width. The strip 20 also carries an identification reference 27. The indicia 1 to 10, emblem 22, base 25 and identification reference 27 are all relatively densely coated with metallic silver particles.
Referring now to Figure 2 which illustrates the use of the image quality indicator just described, there is shown an X-ray source 30, a radiographic film 31, and a specimen 32 to be radiographed positioned between the two. The image quality indicator 20 is placed on the surface of the specimen 32 facing the X-ray source 30, so that it is at least as far away from the radiographic film 31 as any flaw in the specimen 32. The film 31 is then exposed, the exposure conditions being selected, as known in the art, taking into account the thickness and material of the specimen, the distance between the source and the film etc.
After exposure, the film is processed under conditions, known to those skilled in the art, to produce a developed and fixed image.
The image then examined to determine the least densely coated square 1 to 10~that is the region having the least absorptivity-which is discernible on the image. Having done this, the actual density of the square can be read off from the tabulations, hence to give an indication of the quality of the produced radiograph.
The value of the minimum perceptible density may be taken per se as an indication of the quality, or alternatively may be converted to an equivalent thickness of the material of the specimen thus to allow calculation of a conventional percentage image quality indicator sensitivity. The conversion factors for this latter step could be determined by one skilled in the art by plotting a graph of absorption of radiation versus coating density, and a graph of absorption of radiation versus step thickness for the material under examination, at the particular kilovoltage range under examination.These tests could be repeated for all the various materials likely to be examined and for all the kilovoltage ranges normally employed, so that once the coating density of the image quality indicator and the kilovoltage were known, an equivalent thickness of the material under examination could be read off a table.
It will be seen that the square regions 31 are
each discrete surrounded by an area of clear film.
This allows a clear contrast between regions of
different density and hence allows the eye readily
to distinguish the least densely coated square visible on the final radiograph.
The image quality indicator of Figure 1 may conveniently be formed from a suitable radiation sensitive film (e.g. Radiographic or photographic) having a substrate substantially transparent to Xray radiation, and an emulsion of Silver Bromide provided on one or both sides. A master negative is then prepared, the positive image of which corresponds to the Image Quality Indicator. The radiation sensitive film is then exposed to the appropriate radiation through the master negative and then developed and fixed to provide the image quality indicator.
Should the densest coating achievable by this method be insufficient for a particular technique, then multiple layers may be used.
As an alternative to the photographic method just described, an alternative technique would be to produce a master pattern in copper using printed circuit techniques and the image quality indicator then produced either by selective X-ray exposure or more preferably by differential etching of the copper pattern.
The coating densities of the regions 1 to 10
may conveniently be measured using a photographic densitometer.
Claims (11)
1. An image quality indicator which comprises a substrate of material substantially transparent to radiation, having a plurality of selected regions coated with a material absorptive to radiation, each region having a respective predetermined absorptivity whereby on exposure to radiation, each region passes a respective amount of radiation.
2. An image quality indicator as claimed in
Claim 1, wherein each region is spaced from neighbouring regions to provide interstices which are substantially transparent to radiation.
3. An image quality indicator as claimed in
Claim 1 or Claim 2, which further comprises
indicia provided on the substrate adjacent each of
said regions.
4. An image quality indicator as claimed in any of the preceding Claims, which further includes
uniformly coated regions provided on the substrate and spaced apart to define a parallelsided gap of predetermined thickness which is substantially transparent to radiation.
5. An image quality indicator as claimed in any
of the preceding Claims, wherein the substrate is a strip of plastics material.
6. An image quality indicator as claimed in any
of the preceding Claims, wherein the material
absorptive to radiation comprises a particulate
metallic material.
7. A method of manufacturing an image quality
indicator which comprises the steps of
(i) selecting a photographic film comprising a
substrate of material substantially
transparent to radiation having provided
on a surface thereof a photo-sensitive
emulsion,
(ii) exposing selected regions of said film to
respective amounts of radiation,
(iii) processing said film to provide a plurality
of selected regions, each coated with a
material absorptive to radiation and each
having a respective absorptivity.
8. A method of assessing the quality of the image obtained in the radiographic examination of a specimen which includes the steps of
(i) interposing the specimen between a
radiation source and image sensing
means,
(ii) placing adjacent the surface of the
specimen facing the radiation source an
image quality indicator comprising a
substrate of material substantially
transparent to radiation having provided
thereon a plurality of selected regions
coated with a material absorptive to
radiation, each of said regions having a
respective absorptivity, the plurality of
regions including a region with a relatively
low absorptivity, a region having a
relatively high absorptivity and regions
having intermediate absorptivities,
(iii) exposing said specimen to radiation via
said image quality indicator,
(iv) determining from the image sensing
means the region with the lowest
absorptivity perceivable on the image
thereby to assess the quality of the
radiogaphic system.
9. An image quality indicator substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.
10. A method of manufacturing an image quality indicator substantially as hereinbefore described, with reference to and as illustrated in, the accompanying drawings.
11. A method of assessing the quality of the image obtained in a radiographic process, substantially as hereinbefore described, with reference to and as illustrated in, the accompanying drawings.
11. A method of assessing the quality of the aimge obtained
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08327909A GB2129160B (en) | 1982-10-19 | 1983-10-19 | Image quality indicators for radiographic techniques |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8229866 | 1982-10-19 | ||
| GB08327909A GB2129160B (en) | 1982-10-19 | 1983-10-19 | Image quality indicators for radiographic techniques |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8327909D0 GB8327909D0 (en) | 1983-11-23 |
| GB2129160A true GB2129160A (en) | 1984-05-10 |
| GB2129160B GB2129160B (en) | 1986-10-08 |
Family
ID=26284174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08327909A Expired GB2129160B (en) | 1982-10-19 | 1983-10-19 | Image quality indicators for radiographic techniques |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2129160B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2304932A (en) * | 1995-09-06 | 1997-03-26 | Kodak Ltd | Determining correct exposure of film for telecines |
| CN105004742A (en) * | 2015-08-05 | 2015-10-28 | 南车青岛四方机车车辆股份有限公司 | Image quality indicator and radiographic testing quality judgment method applying same |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB216831A (en) * | 1923-05-30 | 1924-08-28 | Mayer Emil | A device for determining photographic exposures |
| GB651068A (en) * | 1947-10-02 | 1951-03-07 | Kodak Ltd | Improvements in or relating to photographic film |
| GB1061638A (en) * | 1964-02-05 | 1967-03-15 | John Dickinson Schneider Inc | Improvements in photomechanical printing processes |
| GB1364624A (en) * | 1971-08-16 | 1974-08-21 | Howson Algraphy Ltd | Simulated continous tone step wedges |
| US3998639A (en) * | 1974-11-19 | 1976-12-21 | Bell Telephone Laboratories, Incorporated | Methods for determining feature-size accuracy of circuit patterns |
| US4004923A (en) * | 1973-11-02 | 1977-01-25 | American Hoechst Corporation | Method of using a test film to measure developer activity |
| EP0025078A1 (en) * | 1979-03-23 | 1981-03-18 | Agfa-Gevaert AG | Method and apparatus for controlling the working condition of a copying apparatus and the subsequent developing apparatus |
-
1983
- 1983-10-19 GB GB08327909A patent/GB2129160B/en not_active Expired
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB216831A (en) * | 1923-05-30 | 1924-08-28 | Mayer Emil | A device for determining photographic exposures |
| GB651068A (en) * | 1947-10-02 | 1951-03-07 | Kodak Ltd | Improvements in or relating to photographic film |
| GB1061638A (en) * | 1964-02-05 | 1967-03-15 | John Dickinson Schneider Inc | Improvements in photomechanical printing processes |
| GB1364624A (en) * | 1971-08-16 | 1974-08-21 | Howson Algraphy Ltd | Simulated continous tone step wedges |
| US4004923A (en) * | 1973-11-02 | 1977-01-25 | American Hoechst Corporation | Method of using a test film to measure developer activity |
| US3998639A (en) * | 1974-11-19 | 1976-12-21 | Bell Telephone Laboratories, Incorporated | Methods for determining feature-size accuracy of circuit patterns |
| EP0025078A1 (en) * | 1979-03-23 | 1981-03-18 | Agfa-Gevaert AG | Method and apparatus for controlling the working condition of a copying apparatus and the subsequent developing apparatus |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2304932A (en) * | 1995-09-06 | 1997-03-26 | Kodak Ltd | Determining correct exposure of film for telecines |
| CN105004742A (en) * | 2015-08-05 | 2015-10-28 | 南车青岛四方机车车辆股份有限公司 | Image quality indicator and radiographic testing quality judgment method applying same |
| CN105004742B (en) * | 2015-08-05 | 2018-04-20 | 中车青岛四方机车车辆股份有限公司 | A kind of ray detection quality judging method of image quality indicator and the application image quality indicator |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8327909D0 (en) | 1983-11-23 |
| GB2129160B (en) | 1986-10-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |