Digital Radiography - PDF by keara

VIEWS: 100 PAGES: 10

									                 PREPRODUCTION INITIATIVE-NELP
      DIGITAL RADIOGRAPHIC SYSTEM (ORDNANCE APPLICATION)
                        FINAL REPORT

                               NSWC INDIAN HEAD, MD

1.0     INTRODUCTION

        The U.S. Navy has adopted a proactive and progressive position toward protecting the
        environment and complying with environmental laws and regulations. Rather than
        merely controlling and treating hazardous waste by end-of-the-pipe measures, the Navy
        has instituted a program for pollution prevention (P2) to reduce or eliminate the volume
        and toxicity of waste, air emissions, and effluent discharges.

        P2 allows the Navy to meet or exceed current and future regulatory mandates and to
        achieve Navy-established goals for reducing hazardous waste generation and toxic
        chemical usage. P2 measures are implemented in a manner that maintains or enhances
        Navy readiness. Additional benefits include increased operational efficiency, reduced
        costs, and increased worker safety.

        The Navy has truly set the standard for the procurement and implementation of P2
        equipment. The Chief of Naval Operations (CNO), Environmental Protection, Safety,
        and Occupational Health Division (N45), established the P2 Equipment Program (PPEP),
        through which both the Naval Air Warfare Center Lakehurst (NAWCADLKE) and the
        Naval Facilities Engineering Service Center (NFESC) serve as procurement agents under
        the direction of N45. P2 equipment is specified and procured under two complementary
        initiatives: the Preproduction Initiative (i.e., technology demonstration) and the
        Competitive Procurement Initiative. The Preproduction Initiative directly supports both
        the Navy Environmental Leadership Program (NELP) for P2 shore applications and the
        P2 Afloat program, which prototypes and procures P2 equipment specific to the needs of
        ships.

        This report provides an analysis of the procurement, installation, and operation of P2
        equipment under the Preproduction Initiative.             Technology demonstrations and
        evaluations are primarily performed under NELP at two designated NELP sites—Naval
        Air Station (NAS) North Island and Naval Station (NS) Mayport. Additional sites such
        as Naval Surface Warfare Center (NSWC) Indian Head have been added as required to
        meet specific mission goals. The program involves defining requirements, performing
        site surveys, procuring and installing equipment, training operators, and collecting data
        during an operational test period. The equipment is assessed for environmental benefits,
        labor and cost savings, and ability to interface with site operations.




305
2.0   BACKGROUND

2.1   Ordnance Inspection at NSWC Indian Head, MD

      The Naval Explosive Ordnance Disposal Technical Division (NAVEODTECHDIV) at
      NSWC Indian Head, MD, is responsible for the radiographic examination of explosive
      ordnance in support of the Department of Defense (DOD) Explosive Ordnance Disposal
      (EOD) program. NAVEODTECHDIV personnel use nondestructive inspection (NDI)
      techniques to examine ordnance before dismantling, disposing, or prescribing handling
      procedures. The site originally used standard radiography techniques (x-ray film) to
      examine ordnance.

      While the quality of the x-ray images was sufficient for the site’s requirements, the
      standard radiography process uses hazardous materials, generates hazardous waste, and
      can be time-consuming. Types of hazardous materials used in the process include
      developers, fixers, and silver. Hazardous wastewater generated during the processing of
      x-ray film contains silver, a heavy metal that has a hazardous waste code of DO11.
      Maryland’s Department of the Environment (MDE) authorizes silver recovery from
      contaminated process wastewater to avoid hazardous waste disposal fees. This end-of-
      pipe processing removes silver from the wastestream to less than the state’s silver
      discharge limit of 5 ppm. The silver recovery process allows discharge of the treated
      wastewater into an approved sanitary system.

      In addition, site personnel often had to repeatedly x-ray the same piece of ordnance from
      different angles and distances to compensate for the object’s varying densities and its
      intricate components. To reduce environmental hazards and costs, as well as to improve
      the ability of personnel to examine ordnance, a digital radiography system was
      recommended for evaluation.

2.2   Digital Radiography Technology Description

      Digital radiography was first implemented commercially in hospitals during the early
      1980s. Recent advances in microprocessing performance have made systems smaller and
      more efficient. This prototype study explored the applicability of digital radiography to
      Navy ordnance inspection.

      When digital radiography is used to view an object, the variations in the object’s features
      and density are “mapped” onto phosphor plates based on differences in radiation
      absorption. The digital radiography technique converts these differentials to differentials
      in phosphor plate ionization, storing the data in the phosphor material until the plate is
      excited by laser light. The light causes the phosphor to luminesce, displaying a latent
      image that is collected by a light guide and subsequently displayed on a computer
      workstation. From this workstation, the image can be transferred and thermally printed
      by a laser printer onto digital radiography film. Digital radiography film is similar to
      conventional x-ray film in size, appearance, and ability to be viewed through
      backlighting; however, it contains no silver.


305
      Phosphor imaging plates replace the traditional method of “wet chemistry” film
      processing. These imaging plates are composed of phosphors that are sensitive to various
      forms of radiation. They store energy produced during exposure and produce a latent
      image by transferring the energy from the impinging radiation to the phosphor crystals.
      The energy is released to create an actual image, which is then digitized by a plate-
      reading device.

      One of the key advantages of digital radiography is its ability to use several features that
      allow electronic data storage, retrieval, enhancement, and transfer. During the scanning/
      reading operation of the image plate, a digital file is created. This original scanned image
      is write-protected by the system and cannot be altered. The system allows only displayed
      changes (e.g., intensities, changes to the gray scale, contrasts, densities, etc.), which are
      referred to as manipulations. The file is then transferred and archived on an optical disk,
      or it can be reviewed and manipulated on a computer workstation. Files can be easily
      transferred electronically, enabling multiple personnel to view and access the image file.
      Also, phosphor image plates can record more information than film, allowing greater in-
      depth analysis and manipulation of an image. This saves labor time and reduces
      hazardous material usage because conventional radiography usually requires that
      multiple shots be taken of the same object. In addition, replacing film with phosphor
      imaging plates eliminates the hazardous materials and hazardous waste associated with
      film development. Furthermore, consumables are minimized because the image plate can
      be used numerous times and can flex around the shape of the object. Finally, worker
      exposure to x-rays is decreased since fewer shots are required and phosphor image plates
      require considerably less radiation than conventional radiography.

3.0   EQUIPMENT DESCRIPTION

3.1   Vendor Selection

      During the equipment selection period, there were two primary vendors with systems on
      the market, Fuji and Liberty Technologies. The Fuji system contains features that
      produce a higher quality image and allow greater latitude in exposure times; therefore, it
      was chosen rather than the Liberty Technologies equipment. Also, the Air Force had
      been studying the Liberty unit as a replacement for conventional radiography used in the
      NDI of aircraft parts. It was determined that, by procuring the Fuji equipment, the Navy
      and Air Force could exchange information about the operability and success of each
      vendor’s equipment.




305
3.2     Fuji Digital Radiography System and Virtual Media Integration

        The Fuji Digital Radiography System and Virtual Media Integration (VMI) equipment
        and software have been integrated to provide one compatible system that allows the
        widespread use of digital radiography. Fuji hardware allows the digital imaging system
        to read/scan the images from phosphor imaging plates and display the images on a
        computer workstation; VMI software allows the images to be enhanced and transmitted
        electronically. Fuji and VMI have provided the site with the following components:

        Fuji Digital Radiography System

        •   AC-3 image plate reader/erasure unit
        •   Image plates and cassettes
        •   HI-C654 workstation to display images; hard-copy capability and system image
            storage capability with VMI-STARR software
        •    Laser printer
        •   “Calzone” enclosures for transportation

        Virtual Media Integration

        •   STARR software, which enhances the digital images and is compatible with VMI
            radiographic scanning digitizers

3.2.1   Fuji Digital Radiography AC-3 Image Plate Reader/Erasure Unit

        The AC-3 Image Plate Reader/Erasure Unit is the main component of Fuji’s hardware
        system. It is a data entry terminal that enables inspection personnel to select various
        “read” routines. Digital enhancements are applied to the image data as it is being
        extracted and compiled. Data entry is accomplished by employing a programmable menu
        drive, manual keyboard and/or magnetic card reader, all of which are provided as part of
        this input device. Constant density enables image files to be displayed at preselected
        gray-scale levels, regardless of exposure parameters (constant density control).

        The AC-3 provides many features and advantages:

        •   Image data is computer-processed, which produces workable images for inspection.
        •   Automatic density adjustment and the wide dynamic range of the imaging plate
            provide high-quality images, resulting in fewer reshots.
        •   The system’s high sensitivity allows for a significant reduction in exposure time.
        •   Digitized image data provide many benefits, including image transmission,
            manipulation, enhancement, and storage.
        •   Easy operation of the system allows for greater consistency by users.




305
3.2.2   The Fuji Digital Radiography CRT Image Console HI-C654

        Fuji’s HI-C654 Image Console displays images on a high-resolution, 21-inch monitor
        and can provide additional image processing capabilities, if necessary. The HI-C654 has
        a proprietary operating system. The images can be displayed or printed individually or
        two, three or four to a screen, which allows faster inspection and an increased confidence
        level.

        The HI-C654 workstation provides the following features and advantages:

        •   High-quality images are produced on the high resolution CRT monitor.
        •   The HI-C654 automatically stores incoming images on its built-in hard disk for
            quicker retrieval of individual images. Images from the Fuji system are written to the
            hard disk in a way that allows for uninterrupted processing of currently displayed
            data. This allows the user to manipulate images while the newest images become
            available.
        •   Images with tonal, magnification, and/or spatial frequency modifications may be
            printed as hard copies on digital radiography film.

3.2.3   Virtual Media Integration, STARR Software

        The VMI software package, called STARR, has been integrated and is compatible with
        the Fuji system. It can convert and compress existing image files for transmission
        electronically, and makes the file compatible with most computers so the recipient can
        view the image file without special software. The STARR software converts a 10-bit
        Fuji image to a TIFF or other 8-bit file format, thereby facilitating communications
        protocol and recordkeeping.

        The STARR software includes the following features and advantages:

        •   STARR software eliminates the use of film, and allows the image files to be accessed
            more readily and sent electronically to multiple personnel.
        •   Converting from the Fuji format to the STARR program increases accuracy, allows
            more images to be read, and reduces the time it takes to evaluate these images.
        •   Image enhancement includes: image threshold, contrast/brightness stretching, image
            rotation 90 degrees, image flip and mirror image crop, image pan and scowl, image
            zoom up to pixel resolution, image annotation, the ability to display density values
            along a line at arbitrary angles, measure distance between any two arbitrary chosen
            points with the measured distance remaining unchanged during zoom or minimize,
            the ability to measure area as a function of density, histogram masking, high pass,
            low pass and median filtration, magnification, and a floating magnification “glass.”
            Customizable image processing kernels of 3 x 3, 5 x 5, 7 x 7, 9 x 9 sizing allows for
            varied edge enhancement and other kernels, positive/negative switching, false color,
            and true optical density with varied backlighting colors. The system has densitometer
            functions, density graphing, histogram functions within a region of interest, and the
            ability to compress files and export images.


305
3.3     Implementation Requirements

3.3.1   AC-3 Image Plate/Erasure Unit

        •   Dimensions (W x D x H): 27-15/16” x 26-13/16” x 41-1/8”
        •   Weight: 81.7 lb.
        •   Electrical: 110V outlet AC 50/60Hz 1kVA
        •   Capable of processing 70 to 90 imaging plates per hour, depending on the size of the
            imaging plate.

3.3.2   Imaging Plates and Cassette

        •   Imaging plates are flexible and reusable.
        •   Standard type imaging plates come in four standard sizes: 14” x 17”, 14” x 14”, 10” x
            12”, and 8” x 10”.
        •   A high image quality (HQ) plate is available in sizes 14” x 17” and 8” x 10”.
        •   Image plate feed and load time is approximately 50 seconds.

3.3.3   HI-C654 Workstation – Hard-Copy Capability

        •   The laser printing device uses a transparent recording media similar in appearance to
            x-ray film.
        •   The hard copy technology is dry (uses no wet chemistry and does not produce
            effluent waste).
        •   Laser copies are thermally processed with typical spatial resolution of 2K x 2K
            pixels/screen.
        •   The user can select the printing format, which is available in either single or multiple
            images per hard copy.

3.3.4   Calzone Case

        Fuji specifically designed the “calzone” cases for NAVEODTECHDIV at NSWC Indian
        Head, MD. They are used to transport and ship the Fuji AC-3 system, video display, and
        imaging plate. Also, the “calzone” provides portability by allowing technicians to
        transport the Fuji AC-3 digital radiography system to a site when performing ordnance
        inspections. The process of shooting, scanning/reading, and manipulating a shot onsite
        with the Fuji digital radiography system provides convenience and no wasted time for the
        technicians. The calzone cases are an additional item and are not always needed when
        purchasing a digital radiography system; however, they provide needed high-impact
        protection if the system is required to be portable.

3.3.5   VMI Workstation - System Image Storage Capability

        This technology uses a SCSI interface to enable the Fuji images to be displayed and


305
        stored on a PC platform. Its subassemblies include:

        •   DASM: SCSI interface with communications port
        •   Pentium 166 PC platform with 32-MHz RAM, 2.1-GB hard drive, CD-ROM burner,
            reader and jazz drive for digital tape
        •   STARR software to enhance and digitally process images exported from digital
            radiography image files. STARR software is compatible with VMI radiographic
            scanning digitizers.

3.4     Benefits

3.4.1   Technical Benefits

        •   Imaging plates have a wide dynamic range and a linear exposure response, which
            means that one exposure covers a wide range of part thicknesses while maintaining
            target densities.
        •   Automatic density controls compensate for either overexposure or underexposure.
        •   Images are stored on disks so they can be quickly retrieved and reviewed.
        •   Radiographic data stored on a disk is preserved indefinitely.
        •   Minimal archival storage space is required.
        •   Digital radiography expands viewable density range by 3 to 4 times over
            conventional film.
        •   Imaging plates can be reused, thereby eliminating the costs associated with
            conventional film.
        •   Images can be electronically transferred to remote viewing sites for instant
            consultation and analysis.
        •   Radiation safety concerns are reduced because a smaller dose is required.
        •   Environmental concerns associated with film processing are eliminated, including the
            discharge of silver and other spent hazardous photographic chemicals.
        •   Image analysis is improved by reducing interpreter subjectivity.

3.4.2   Environmental and Cost Benefits

        The Fuji system and VMI equipment provide several benefits when compared to
        conventional radiography, including:

        •   Eliminates film processing chemicals and hazardous wastes and materials.
        •   Reduces the cost of hazardous waste disposal.
        •   Eliminates the need to perform silver recovery processing.
        •   Eliminates precleaning of the film developing machine.
        •   Eliminates the requirement for procurement of x-ray film.
        •   Provides a healthier work environment/reduced exposure to radiation.
        •   Reduces labor hours required for weapons inspection.
        •   Expands the capabilities of weapons disarmament field personnel.
        •   Facilitates the electronic transfer of images from the field or between experts for


305
            consultation and analysis.
        •   Eliminates reshooting multiple exposures by allowing electronic manipulation of the
            images.

4.0     DATA ANALYSIS

4.1     Quantitative Analysis

        Compared to the traditional wet chemistry process, the Fuji system has a 10-year return
        on investment (ROI) of $1,432,746.90 per unit, with a break-even point of 1.89 years
        (refer to the Cost Analysis for complete data).

4.2     Qualitative Analysis

4.2.1   Installation

        Installation occurred without any significant difficulties. The Fuji AC-3 system was
        operational within 2 ½ hours. Some minor hardware problems were quickly corrected by
        the vendor. These problems had no bearing on the newly installed equipment. To date,
        no problems have been reported.

4.2.2   Training

        Training took place in two phases. During Phase I, NAVEODTECHDIV personnel were
        given a 1½-day tutorial on the basics of the system. Personnel were able to use the unit
        after less than one day of training. Next, the system operated for a month so personnel
        could become more familiar with system capabilities before the Phase II training. By the
        end of the second phase of training, site personnel were using the advanced features and
        were proficient with all system functions.

4.2.3   Maintainability

        The unit has experienced no problems with maintainability and has not required repairs.
        Standard maintenance consists of a basic preventive maintenance program. Fuji has a
        strong customer support program with a toll-free number for users to call if any problems
        arise. Troubleshooting advice is given over the phone and, if repair is required, a Fuji
        technician can usually be onsite within one day.




305
4.2.4   Interface with Site Operations

        The site readily and eagerly integrated the equipment into its procedures. During initial
        testing of the unit, both traditional wet chemistry and digital radiographic methods were
        used and the results were compared. Eventually, the workers switched solely to digital
        radiography in the interest of saving time and because there was no longer a need for
        redundant testing. Site personnel judged the quality of digital radiograph images to be
        better than or equal to the x-ray film images.

4.2.5   Overall Performance

        The Fuji and VMI equipment has performed very well. The digital radiography process
        required less time during the developing and manipulation stages than traditional wet
        chemistry photo processing. The “developing” stage of digital radiography can be
        described as scanning the exposed image plate and downloading the image into the Fuji
        AC-3. During the “manipulation” stage, the original scanned image is saved on the hard
        drive of the computer and cannot be changed. This image can then be manipulated on the
        computer workstation until an acceptable image is present onscreen. Developing time
        was reduced from 15 minutes to 1 minute, a 93.3% reduction, and manipulating the
        object was reduced from 60 minutes to 4 minutes, also a 93.3% reduction. Digital
        radiography requires no chemicals when developing the image, while traditional wet
        chemistry does. Often, objects that were difficult to x-ray and which required multiple
        shots required only one exposure with the digital radiographic equipment.

        Some advantages realized by the Fuji system included:

        •   Scan time of approximately 45 seconds.
        •   Ability to scan and erase the phosphor plate in one operation.
        •   Minimum amount of equipment; only three major components (scanner, laser printer,
            and computer workstation).
        •   Fixed scan rate of 75 microns.
        •   Ability to preprogram specific inspection parameters.

        These advantages allowed the maximum performance of the Fuji system. The system’s
        capabilities proved to be superior to any conventional x-ray method.

4.2.6   Future Uses

        Possible additional sites for the digital radiographic system within the ordnance
        inspection area include, but are not limited to: NSWC Yorktown, VA; NSWC Concord,
        CA; NSWC China Lake, CA; NSWC Crane, IN. The sites listed are not prioritized in
        any specific order. The digital radiographic system has proven its success and has the
        potential to be used at many other Navy facilities.




305
5.0   LESSONS LEARNED
      Because of the classified nature of much NAVEODTECHDIV work, three removable
      hard drives for the equipment are recommended. For operations where sensitive material
      is x-rayed, security must be programmed into the system to ensure that unauthorized
      personnel cannot read classified files.

      The VMI system has capabilities that limited its performance at the time the software was
      offered to NSWC Indian Head. Initially, NSWC Indian Head received an early version
      of the software. Today, VMI’s software is fully compatible with the Fuji System. VMI
      also offers upgrades to its STARR software for registered users. Any new developments
      of the software will be offered in the future. The software package and upgrades can be
      downloaded from VMI’s website.

6.0   CONCLUSIONS
      Digital radiography is an excellent alternative/replacement to conventional radiography.
      Its advantages outweigh those of standard x-ray procedures as described in Sections 3.2
      and 3.4. When digital radiography was implemented into the daily routine at NSWC
      Indian Head, MD, it proved to make radiography an easier process. By providing a side-
      by-side comparison of the conventional radiography and digital radiography, NSWC
      radiologists were able to compare data and agree to the success of the test period. It was
      proven that digital radiography not only saves time and money, but also that the
      technology is superior to conventional methods.




305

								
To top