Digital Digital RadiographyRadiography

Chapter 22Chapter 22

History of Digital History of Digital RadiographyRadiography

Slower process of conversion Slower process of conversion because no pressing need to convert because no pressing need to convert to digital radiography.to digital radiography.

Requires a large amount of digital Requires a large amount of digital data.data.

OverviewOverview

Primary difference is that digital radiographs Primary difference is that digital radiographs are electronically captured, recorded and are electronically captured, recorded and viewed at a computer terminal which replaces viewed at a computer terminal which replaces the radiographic film and the view box.the radiographic film and the view box.

Screen and cassette is replaced by a reusable Screen and cassette is replaced by a reusable image receptor or detector.image receptor or detector.

Receptor receives x-rays and exposes a digital Receptor receives x-rays and exposes a digital plate that transforms light to an electrical plate that transforms light to an electrical image.image.

Hardware is essentially same (X-ray tube, Hardware is essentially same (X-ray tube, stand, etc). stand, etc).

Once digital radiographic image is Once digital radiographic image is made, it is transferred to a dedicated made, it is transferred to a dedicated digital radiography computer for digital radiography computer for “image processing”.“image processing”.

Image can then be adjusted, rotated, Image can then be adjusted, rotated, etc.etc.

Limitations of Conventional Limitations of Conventional Screen-film RadiographyScreen-film Radiography

Limitations:Limitations: Require fairly narrow exposure factors Require fairly narrow exposure factors

to produce a diagnostic quality to produce a diagnostic quality radiograph.radiograph.

Radiographic image can not be adjusted Radiographic image can not be adjusted once it is made.once it is made.

Requires physical handling and storage.Requires physical handling and storage.

Advantages of Digital Advantages of Digital RadiographyRadiography

The imageThe image Image can be adjusted after exposure.Image can be adjusted after exposure. Need for re-takes are minimized.Need for re-takes are minimized. Computer manipulation of the digital Computer manipulation of the digital

image is possible.image is possible. Able to see soft tissue and bony detail in Able to see soft tissue and bony detail in

single image.single image. Studies show that digital films are equal Studies show that digital films are equal

or better than traditional film for or better than traditional film for evaluating most body parts.evaluating most body parts.

TimeTime Reduces time takes to produce image.Reduces time takes to produce image. Reduces time taken in re-takes.Reduces time taken in re-takes. Reduces processing time.Reduces processing time. Time to correctly label and store.Time to correctly label and store.

Image storage and TransportImage storage and Transport Stored in computer and not physically Stored in computer and not physically

stored in clinic.stored in clinic. Quick access to digital image.Quick access to digital image. Ease of transfer of image.Ease of transfer of image.

Cost Savings and Increasing ProfitsCost Savings and Increasing Profits Overall initial cost is higher, but due to saving Overall initial cost is higher, but due to saving

time and materials, actually will be cheaper in time and materials, actually will be cheaper in the long term.the long term.

Digital improves quality of imaging studies, Digital improves quality of imaging studies, which leads to better diagnosis.which leads to better diagnosis.

Follow-up RadiographyFollow-up Radiography Comparison to previous radiographs is easier.Comparison to previous radiographs is easier. Not worried about lost or misplaced Not worried about lost or misplaced

radiographs.radiographs.

Disadvantages of Digital Disadvantages of Digital RadiographyRadiography

Training and Learning CurveTraining and Learning Curve Must learn machinery, technology and Must learn machinery, technology and

positioning.positioning. Must still adhere to good technique for Must still adhere to good technique for

acquiring images.acquiring images. Equipment costEquipment cost

Initial cost is high compared with Initial cost is high compared with traditional radiography.traditional radiography.

Other technology costs associated with Other technology costs associated with digital radiology (computers, servers, etc).digital radiology (computers, servers, etc).

Image Management Image Management Software and Image Software and Image

ProcessingProcessing Some digital radiology machines Some digital radiology machines

have pre-set selections based on have pre-set selections based on species, body part of interest, and species, body part of interest, and radiographic view to further identify radiographic view to further identify the study type. the study type.

Images will be sent to workstation or Images will be sent to workstation or printed on transparent film for printed on transparent film for viewing.viewing.

Analog-to-Digital Analog-to-Digital Radiographic Signal Radiographic Signal

ConversionConversion Conventional radiograph is produced by Conventional radiograph is produced by

a series of analog signals, from x-ray a series of analog signals, from x-ray formation and interaction with the formation and interaction with the patient, to capture of x-rays by the patient, to capture of x-rays by the intensifying screen, which converts to intensifying screen, which converts to light which produces image on the film.light which produces image on the film.

Digital x-ray converts the analog signal Digital x-ray converts the analog signal of the light to a digital signal. Converts of the light to a digital signal. Converts the waves to a digital signal. the waves to a digital signal.

Digital ComputersDigital Computers

Digital waveform is represented Digital waveform is represented numerically by binary numbers.numerically by binary numbers.

Computer memory and storage Computer memory and storage consist of bits (binary digits).consist of bits (binary digits).

Eight bits become one byte.Eight bits become one byte.

Pixels and Image MatrixPixels and Image Matrix

X-ray beam is converted into a X-ray beam is converted into a electronic form that is digitized and electronic form that is digitized and converted to squares of information converted to squares of information known as pixels.known as pixels.

The smaller the pixel, the better the The smaller the pixel, the better the image quality.image quality.

Viewing Digital ImagesViewing Digital Images

Display MonitorsDisplay Monitors Consideration given to size and typeConsideration given to size and type

Film and PaperFilm and Paper Should be printed on high-quality, Should be printed on high-quality,

transparent laser film and can be transparent laser film and can be viewed on viewbox.viewed on viewbox.

Digital Receptors Available Digital Receptors Available in Veterinary Medicinein Veterinary Medicine

Computed Radiography (CR)Computed Radiography (CR) Similar to traditional radiography where CR Similar to traditional radiography where CR

cassette is exposed, opened and image is cassette is exposed, opened and image is removed from CR plate, then plate is erased removed from CR plate, then plate is erased and returned to cassette for reuse.and returned to cassette for reuse.

Flat Panel DetectorsFlat Panel Detectors Detectors in a panel that is hard wired to a Detectors in a panel that is hard wired to a

computer.computer. Charged Coupled Device (CCD)Charged Coupled Device (CCD)

Small flat panel that is capable of producing Small flat panel that is capable of producing images from visible light. images from visible light.

Digital ArtifactsDigital Artifacts

Image plate artifactsImage plate artifacts Cracks and bends in platesCracks and bends in plates

Image processing artifactsImage processing artifacts Halo effects, computer artifactsHalo effects, computer artifacts