Digital And Film Radiography Comparison And Contrast .
Digital and Film RadiographyComparison and ContrastReference HandoutA Special Seminar for the ASNT Fall 2015 Conference
Terms and Definitions Direct Radiography (DR)* – Radiography thatconverts radiation directly to stored image data. Indirect Radiography – Radiography that usesan intermediate storage medium prior tostorage of the image data. *Overloaded Acronyms and terms – Acronymsand terms are often used to mean differentthings, and we need to be careful to try tocommunicate clearly. For example:2
Cameras3
Terms & Definitions Film Radiography (RT) A form of radiographic imaging, where photographic film isexposed to radiation transmitted through an item beinginspected, and light or radioactive rays, an invisible image(called a latent image) and a latent image is formed in theemulsion layer of the film. Conversion of the latent image toa visible image is through chemical processing. TraditionalFilm Radiography must use more radiation to produce animage of similar contrast to digital methods. The image is stored on a sheet of radiographic film which isviewed based on the transmission of light through the film.4
Terms and DefinitionsDigital Radiography (DR) A form of radiographic imaging in which digital detectors are exposed tothe radiation transmitted through an item being inspected, and convert thetransmission data to a digital file to be stored and displayed on acomputer. A form of radiographic imaging, where digital radiographic sensors areused instead of traditional radiographic film. Advantages include timeefficiency through bypassing chemical processing and the ability todigitally transfer and enhance images. Also, in most cases, less radiationcan be used to produce an image of similar contrast to film radiography. Instead of radiographic film, digital radiography uses a digital imagecapture device. This gives advantages of immediate image preview andavailability; elimination of costly film processing steps; a wider dynamicrange, which makes it more forgiving for over- and under-exposure; aswell as the ability to apply special image processing techniques thatenhance overall display of the image.
Terms and DefinitionsComputed Radiography (CR) Digital Radiography using storage phosphor plates as anintermediate storage media prior to scanning the plate to create adigital image. Implementation is similar to film radiography except that in place ofa film to create the image, an imaging plate (IP) made ofphotostimulable phosphor is used. The imaging plate is housed in a cassette and placed under thebody part or object to be examined and the radiographic exposureis made. Hence, instead of taking an exposed film into a darkroomfor developing in chemical tanks or an automatic film processor,the imaging plate is run through a special laser scanner, or CRreader, that reads and digitizes the image.6
Terms and DefinitionsComputed Tomography (CT) Digital Radiography that allows data to be displayed in a nonstandard manner. Implementation requires additional image acquisition, additionalhandling hardware, and complex image processing algorithms Makes use of computer-processed combinations of manyradiographic images taken from different angles to produce crosssectional (tomographic) images (virtual 'slices') of specific areas ofa scanned object, allowing the user to see inside the object withoutcutting. Image processing is used to generate a three-dimensional imageof the inside of the object from a large series of two-dimensionalradiographic images taken around a single axis of rotation.7
Film vs Digital ComparisonFilmDigitalDevelopment timeFaster (immediate or near immediateresults)Technology and equipment well knownand understoodTechnology continuously developingand not as well understoodRequires HAZMAT chemical processing No HAZMAT chemicalsPhysical transfer of filmElectronic transfer of dataSimpler and better known processcontrolsMore complex for setup and processcontrolsWider dynamic rangeAbility to process and manipulate dataRequires less radiation and time forexposures8
Radiation Spectrum Radiographic inspection utilizes energy levels exceeding ultraviolet light Develops penetrating, and ionizing capabilities Causes a reaction in the detector used to develop an observable image Areas of higher density will allow less radiation to pass through, whileareas of lower density will allow more radiation to pass through. Thiscreates an image of defects of higher or lower density than the materialaround it.9
Nyquist-Shannon SamplingTheorem This theorem is typically utilized in digitalradiography to answer the all importantquestion:What resolution do I need to see the level ofdetail required for a given flaw size?10
Nyquist-Shannon Sampling TheoremDefinition (abbreviated):“In the field of digital signal processing, the sampling theorem is afundamental bridge between continuous-time signals (often called "analogsignals") and discrete-time signals (often called "digital signals"). It establishes asufficient condition for a sample rate that permits a discrete sequence of samplesto capture all the information from a continuous-time signal of finite bandwidth.” 1“The sampling theorem introduces the concept of a sample rate that issufficient for perfect fidelity for the class of functions that are bandlimited to agiven bandwidth, such that no actual information is lost in the sampling process. Itexpresses the sufficient sample rate in terms of the bandwidth for the class offunctions. The theorem also leads to a formula for perfectly reconstructing theoriginal continuous-time function from the samples.” 11Excerpts from Wikipedia, the free encyclopedia.11
Nyquist-Shannon Sampling Theorem Critical frequency . 1To illustrate the necessity of fs 2B, consider the family of sinusoids (depicted in Fig. 8) generated by different values of θ in this formula:With fs 2B or equivalently T 1/(2B), the samples are given by:12
Nyquist-Shannon sampling theoremPixel pitch ρNyquist frequency ½ ρ LP/mmExamples 50 μm pixel pitch: NF 10 LP/mm 100 μm pixel pitch: NF 5 LP/mm 200 μm pixel pitch: NF 2.5 LP/mm13
What is Noise? In Film Radiography noise is caused by scatter, is oftenreferred to as graininess and can be corrected by usinga finer film. In DR noise is caused by scatter, undesired radiationand other electronic effects that vary by the type ofdetector. In digital techniques, a number on a brightness scale isassigned to a particular value of radiation dose tocreate an image, when unwanted radiation is present, ittakes up those values, reducing the range of valuesand sensitivity of the test.14
Viewing Noise on a Histogram A histogram is a representation of all values assignedto every level of dose received on the digital detector. If a particular system was capable of assigning 65,536gray scale values, a test that assigned 45,000 of thosevalues to radiation that passed through the part wouldbe more sensitive then a test that had more scatter andonly assigned 25,000 values to the radiation thatpassed through the part.15
Viewing Noise on a Histogram This can be seen by looking at the histogram andviewing the assigned gray scale values.16
Noise Comparison17
Source-DetectionOptimizationFilmDigitalUse proper energy to avoidover/under exposureUse proper energy and flux to avoiddetector saturation (blooming effect)or damageUse of the “cleanest” source possibleand shield detector system to reducebackground and scatter problemsMeasurements at different energiescan be used to increase/changecontrast (ratio of radiographs atdifferent energies for example)Depth-of-field can be adjusted withdistance scintillator/converter-tosensor18
DR SYSTEM COMPONENTS19
Computed RadiographyHow is CR Different Than Film The CR Image Plate (IP) functions in a completely different fashion than filmCR has substantially wider latitude than filmThe exposure process requires a different approach partly due to scatterThe CR scanner functions in a completely different fashion than film processorThe CR image is displayed on a computer monitor instead of a light boxSoftware tools are used to adjust the image in ways film can’t be changedImage quality measured by Signal to Noise Ratio (SNR) using software toolsAdditional operator training is requiredTHE ENTIRE PROCESS OF CREATING AN IMAGEUSING Computed RadiographyIS DIFFERENT THAN FILM !
CCD CCD: Charge Coupled Device Advantages: Large field of view (FOV) High Quantum Efficiency (QE) Different speed read-out (up to a few MHz) Disadvantages: Relatively slow system (seconds acquisition time) Lengthy transfer of the data causing dead time betweenacquisition of radiograph (seconds) Dark current not negligible (reduced when CCD is cooled)21
Detector ComparisonFilmDigitalFilm SpeedCR and DR generally faster requiring lower dose.Limited Latitude.Logarithmic film curves.CR and DDA’s have extremely high latitude (bit depth)and linear response. 12, 16, or 32-bit gray scaleAutomatic or manual film processingCR Scanning of IPs.Direct link on DDA’sComputer Image Processing to produce images.Reliance on Chemicals andClean processingManual Film Cassette HandlingAutomation allows CT scans in seconds to minutes,Radiography in fractions of secondsCR can be setup to handle same as film.Storage of Film in large vaults with possibledegradation of image.Storage of data on file servers requires little space,and indefinite shelf life.Capability to perform lens-based magnificationLifetime is years (with appropriate shielding)Flexibility in field-of-view and spatial and/or timeresolution22
Computed Tomography Radiographs are limited to the collapsing of a 3D object on a 2Dimage Computed/Computerized Tomography (CT) allows reconstructionof the information inside an object Reconstruction of a 3D object from 2D radiographs/projections atdifferent angles around the object: Usually stepping angle is fixed Reconstruction provides cross-sections of the object showingdensity/linear attenuation coefficient mapping Some reading material: G. T. Herman, “Fundamentals ofComputerized Tomography”, Springer, ISBN: 978-1-85233-617-223
Reconstruction Several algorithms can be used to reconstruct an object in3D: Filtered-back projection: Works in Fourier Space Fast but requires data acquisition of projections at a definedstepping angle Little to no missing projection Object with good contrast/attenuation Iterative reconstruction Works in Real SpaceComputer-intensiveIs able to reconstruct an object even with missing projectionsCan reconstruct objects with very low contrast/attenuation24
Reconstruction Algebraic – Algorithm that iteratively solves a system oflinear equations Bayesian – Algorithm that works based calculating aresult using probabilistic mathematics Compressive Sampling – Reconstruction based onminimizing the sparseness of data25
Filtered Back Projection Projection is smeared back across the reconstructedimage Based on Radon Transform Filtering performed beforenormalization Similar to Fourier Transform:line integrals through f(x,y) Data is moved to reciprocalspace (1/real OCAL COPIES/AV0405/HAYDEN/Slice Reconstruction.html Data is filtered before reconstruction Sharp filter improves achievable spatial resolution26
DDA vs. CR vs. FilmProcess/criteriaDDA RadiographyComputed RadiographyFilmProcedure:Direct ImageIP ScannerFilm DevelopmentResolution: High Quality FilmEquivalent to MX125Universal Image Std.Image Format:Digital – Discrete PixelsDigital – Sampled PixelsAnalogTime to image:Seconds or LessUp to 90 sec10-30 minEnvironmental:NoneNoneChemical DisposalSoftware AdjustSoftware AdjustCannot Adjust 160K 100K 80KOccasional DetectorSmall – Replace IPRelatively LargerN/AFlex or rigidFlex or rigidElectronicElectronicPhysicalComputer and MonitorComputer & MonitorDark RoomSemi portableYesYesImage Enhancement:Equipment Cost:Consumable Cost:Cassette:Image Storage:Equipment Space:Portability:
Techniques Film – Film Speed, Processor Type, Source to Film Distance,Energy Level, exposure time DR – Detector Type, Image Processing, Energy Level, Source toObject Distance, Source to Detector Distance, CNR/SNR Usage,Monitor (selection, verification), automation, measurement toolcalibration CR Plates – sampling rate, pixel resolution of scanner, exposuretime DDA – pixel resolution of detector, exposure time, frameaveraging, detector calibrations CCD Camera – pixel resolution, exposure time, image averaging,detector calibrations, detector cooling, florescent screen properties(thickness, brightness, decay, grain size), lens properties (focalspot, F-Stop)28
ASTM StandardsGeneral RadiographyNeutron Radiography94 – Radiographic ExaminationSTP-624 Neutron Radiography747- Wire IQIsE-803-91 Determination of L/D ratio801 – RT of Electronic DevicesE-748 Thermal Neutron Radiography1025 – Hole Type IQIsE-748-2 Thermal Neutron Radiography1030 – RT of Metal CastingsE-2023-11 Fabrication of Neutron RadiographicSensitivity Indicators1032 – RT of WeldsE-2003-10 NRT Beam Purity Indicators1165 - Focal Spots for X-ray tubesE-2861-11 Measurements of Beam Divergence andAlignment in Neutron Radiographic Beams1411 – Qualification of RT SystemsE-721-11 Neutron Energy Spectra from Neutron Sensors forRadiation-Hardness Testing for Electronics1647 – Contrast Sensitivity1817 – Use of Radiographic QualityIndicators29
ASTM StandardsFilmDigital999 - Film Processing1255 – Radioscopy1079 - Densitometer Calibration1416 – Radioscopy of Welds1254 – Storage of Radiographs andFilm1441 – Guide for CT Imaging1390 – Illuminators for RT1475 – Computer Fields forTransferring Digital Data1815 – Classification of Film Systems 1570 – Standard Practice for CT1695 – Test Method for CT SystemPerformance2002 – Image Unsharpness2007– Standard Guide for CR30
ASTM StandardsFilm (continued)DR (continued)2033 – Standard Practice for CR2339 - DICONDE2445 – Long Term Stability forCR2446 – Classification of CRSystems2597 – Characterization DDAs2698 – Standard Practice forUsing DDA2736 – Guide for DDAStandards with reference images were ignored forpurposes of this comparison31
ASTM StandardsFilm (continued)DR (continued)2737 – Long Term StabilityDDARP 133 – SMPTE MonitorTest PatternStandards with reference images were ignored forpurposes of this comparison32
ASTM StandardsThere are specific standards applicable to each of theradiographic modalities, covering: General Radiography – 10 standards Neutron Radiography – 8 standards Film Radiography – 5 standards Digital Radiography – 17 standards33
DetectorImage ReviewProcess controls for imagequalityNeutronRadiographyIsotopeElectrical (accelerator)Nuclear ReactorFilmReader must understandneutron attenuation; Filmviewer with opticalmagnification (loupe,magnifying glass, etc.)Film density, different IQIbased on difference inradiation attenuationFilm radiographyIsotopeElectrical (tube or accelerator)FilmFilm viewer with opticalmagnification (loupe,magnifying glass, etc)Film densityDigital Radiography(DR)IsotopeElectrical (tube or accelerator)Linear ArrayCMOSDR PanelCamerasComputer Review with imagemanipulation and analysistoolsMonitor checks, CNR, SNR,image processing filters,detector calibrationsDigital Radiography(CR)IsotopeElectrical (tube or accelerator)Phosphor Imaging PlatesComputer Review with imagemanipulation and analysistoolsMonitor checks, CNR, SNR,image processing filtersIsotopeElectrical (tube or accelerator)Linear ArrayCMOSDR PanelCamerasComputer Review with imagemanipulation and analysistoolsMonitor checks, CNR, SNR,image processing filters,detector calibrationsSourceComputedTomography (CT)34
Summary Overview of Digital and Film Radiography waspresented: Further in-depth understanding is critical fordigital radiography as the field is broad and isconstantly evolving Method selection depends on the source andthe application (for example, fast kinetics withms time resolution may be best suited withdigital imaging, whereas hard-to-reach fieldapplications may be better suited with film)
Summary Digital capabilities are versatile andflexible, provide the capability to collectdata with higher dynamic range, andrequire image processing and analysisexpertise, along with equipment set-upknowledge and fast computers/serversfor data storage, processing and analysis.
ASTM StandardsE 94E192E 543E 592Standard Guide for Radiographic ExaminationReference Radiographs of Investment Steel Castings for Aerospace ApplicationsStandard Specifications for Agencies Performing Nondestructive TestingStandard Guide to Obtainable ASTM Equivalent Penetrameter Sensitivity for Radiography of SteelPlates 1/4 to 2 in. (6 to 51 mm) Thick with X-Rays and 1 to 6 in. (25 to 152 mm) Thick with Cobalt-60E 746 Standard Practice for Determining Relative Image Quality Response of Industrial RadiographicImaging SystemsE 747 Standard Practice for Design, Manufacture, and Material Grouping Classification of Wire Image QualityIndicators (IQI) Used for RadiologyE 748 Standard Practices for Thermal Neutron Radiography of MaterialsE 801 Standard Practice for Controlling Quality of Radiological Examination of Electronic DevicesE 999 Guide for Controlling the Quality of Industrial Radiographic Film ProcessingE 1000 Standard Guide for RadioscopyE 1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image QualityIndicators (IQI) Used for RadiologyE 1030 Standard Test Method for Radiographic Examination of Metallic CastingsE 1032 Standard Test Method for Radiographic Examination of WeldmentsE 1079 Practice for Calibration of Transmission DensitometersE 1165 Standard Test Method for Measurement of Focal Spots of Industrial X-Ray Tubes by Pinhole ImagingE 1254 Standard Guide for Storage of Radiographs and Unexposed Industrial Radiographic FilmsE 1255 Standard Practice for RadioscopyE 1316 Standard Terminology for Nondestructive ExaminationsE 1390 Standard Specification for Illuminators Used for Viewing Industrial RadiographsE 1411 Standard Practice for Qualification of Radioscopic SystemsE 1441 Standard Guide for Computed Tomography (CT) ImagingE 1453 Standard Guide for Storage of Media that Contains Analog or Digital Radioscopic DataE 1475 Standard Guide for Data Fields for Computerized Transfer of Digital Radiological Examination DataE 1570 Standard Practice for Computed Tomographic (CT) ExaminationE 1647 Standard Practice for Determining Contrast Sensitivity in RadiologyE 1672 Standard Guide for Computed Tomography (CT) System SelectionE 1695 Standard Test Method for Measurement of Computed Tomography (CT) System PerformanceE 1735 Standard Test Method for Determining Relative Image Quality of Industrial Radiographic Film Exposedto X-Radiation from 4 to 25 MeVE 1742 Standard Practice for Radiography ExaminationE 1815 Standard Test Method for Classification of Film Systems for Industrial RadiographyE 1817 Standard Practice for Controlling Quality of Radiological Examination by Using Representative QualityIndicators (RQIs)E 2002 Standard Practice for Determining Total Image Unsharpness in RadiologyE 2003 Standard Practice for Fabrication of the Neutron Radiographic Beam Purity IndicatorsE 2007 Standard Guide for Computed Radiology (Photostimulable Luminescence (PSL) Method)E 2033 Practice for Computed Radiology (PSL Method)E 2339 Standard Practice for Digital Imaging and Communication in Nondestructive Evaluation (DICONDE)E 2422 Standard Digital Reference Images for Inspection of Aluminum CastingsE 2445 Standard Practice for Qualification and Long-Term Stability of Computed Radiology SystemsE 2446 Standard Practice for Classification of Computed Radiology SystemsE 2597 Standard Practice for Manufacturing Characterization of Digital Detector ArraysE 2660 Standard Digital Reference Image
Terms and Definitions Computed Radiography (CR) Digital Radiography using storage phosphor plates as an intermediate storage media prior to scanning the plate to create a digital image. Implementation is similar to film radiography except that in place of a film to create the image, an imaging plate (IP) made of
Thomas F. Fisher, PhD, OTR, CCM, FAOTA; Dean, College of Health Sciences . Goshen Hospital Stephanie Lueking, Radiography Clinical Instructor . Elkhart General Hospital Mark Holcomb, Radiography Clinical Instructor . Memorial Hospital Jeanne Renken, Radiography Clinical Instru
KODAK RVG 6500/6100/5100 Digital intraoral radiography KODAK RVG 6100 Digital Radiography System Can be
Introduction Digital alternatives of radiography, both the computed radiography (CR) and the digital radiography (DR), have been accepted well for the clinical use.
Drying 20 minutes Hang film in film dryer at the notched corner and catch drips with Kim Wipe. Clean-Up As film is drying, wash and dry all graduates and drum for next person to use. Sleeve Film Once the film is done drying, turn dryer off, remove film, and sleeve in negative sleeve. Turn the dryer back on if there are still sheets of film drying.
Film guide 5 Film is both a powerful communication medium and an art form. The Diploma Programme film course aims to develop students' skills so that they become adept in both interpreting and making film texts. Through the study and analysis of film texts and exercises in film-making, the Diploma Programme film
1920 - Nitrate negative film commonly replaces glass plate negatives. 1923 - Kodak introduces cellulose acetate amateur motion picture film. 1925 - 35mm nitrate still negative film begins to be available and cellulose acetate film becomes much . more common. 1930 - Acetate sheet film, X-ray film, and 35mm roll film become available.
2. The Rhetoric of Film: Bakhtinian Approaches and Film Ethos Film as Its Own Rhetorical Medium 32 Bakhtinian Perspectives on the Rhetoric of Film 34 Film Ethos 42 3. The Rhetoric of Film: Pathos and Logos in the Movies Pathos in the Movies 55 Film Logos 63 Blade Runner: A Rhetorical Analysis 72 4.
-Animal Nutrition Report Categories: CSSF Activity Report Approved By: James Johnson, Agricultural Affairs Officer Prepared By: Swe Mon Aung, Agricultural Specialist Report Highlights: In July 2019, FAS sent five Myanmar private feed millers and importers to the United States on a Cochran Fellowship Program to learn more about feed and feed ingredients available in the United States poultry .
