Digital Radiography Chapter 22

History of Digital Radiography Slower process of conversion because no pressing need to convert to digital radiography. Slower process of conversion because no pressing need to convert to digital radiography. Requires a large amount of digital data. Requires a large amount of digital data.

Overview Primary difference is that digital radiographs are electronically captured, recorded and viewed at a computer terminal which replaces the radiographic film and the view box. Primary difference is that digital radiographs are electronically captured, recorded and viewed at a computer terminal which replaces the radiographic film and the view box. Screen and cassette is replaced by a reusable image receptor or detector. Screen and cassette is replaced by a reusable image receptor or detector. Receptor receives x-rays and exposes a digital plate that transforms light to an electrical image. Receptor receives x-rays and exposes a digital plate that transforms light to an electrical image. Hardware is essentially same (X-ray tube, stand, etc). Hardware is essentially same (X-ray tube, stand, etc).

Once digital radiographic image is made, it is transferred to a dedicated digital radiography computer for “image processing”. Once digital radiographic image is made, it is transferred to a dedicated digital radiography computer for “image processing”. Image can then be adjusted, rotated, etc. Image can then be adjusted, rotated, etc.

Limitations of Conventional Screen- film Radiography Limitations: Limitations: Require fairly narrow exposure factors to produce a diagnostic quality radiograph. Require fairly narrow exposure factors to produce a diagnostic quality radiograph. Radiographic image can not be adjusted once it is made. Radiographic image can not be adjusted once it is made. Requires physical handling and storage. Requires physical handling and storage.

Advantages of Digital Radiography The image The 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 image is possible. Computer manipulation of the digital image is possible. Able to see soft tissue and bony detail in single image. Able to see soft tissue and bony detail in single image. Studies show that digital films are equal or better than traditional film for evaluating most body parts. Studies show that digital films are equal or better than traditional film for evaluating most body parts.

Time Time 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 Transport Image storage and Transport Stored in computer and not physically stored in clinic. Stored in computer and not physically 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 Profits Cost Savings and Increasing Profits Overall initial cost is higher, but due to saving time and materials, actually will be cheaper in the long term. Overall initial cost is higher, but due to saving time and materials, actually will be cheaper in the long term. Digital improves quality of imaging studies, which leads to better diagnosis. Digital improves quality of imaging studies, which leads to better diagnosis. Follow-up Radiography Follow-up Radiography Comparison to previous radiographs is easier. Comparison to previous radiographs is easier. Not worried about lost or misplaced radiographs. Not worried about lost or misplaced radiographs.

Disadvantages of Digital Radiography Training and Learning Curve Training and Learning Curve Must learn machinery, technology and positioning. Must learn machinery, technology and positioning. Must still adhere to good technique for acquiring images. Must still adhere to good technique for acquiring images. Equipment cost Equipment cost Initial cost is high compared with traditional radiography. Initial cost is high compared with traditional radiography. Other technology costs associated with digital radiology (computers, servers, etc). Other technology costs associated with digital radiology (computers, servers, etc).

Image Management Software and Image Processing Some digital radiology machines have pre-set selections based on species, body part of interest, and radiographic view to further identify the study type. Some digital radiology machines have pre-set selections based on species, body part of interest, and radiographic view to further identify the study type. Images will be sent to workstation or printed on transparent film for viewing. Images will be sent to workstation or printed on transparent film for viewing.

Analog-to-Digital Radiographic Signal Conversion Conventional radiograph is produced by a series of analog signals, from x-ray formation and interaction with the patient, to capture of x-rays by the intensifying screen, which converts to light which produces image on the film. Conventional radiograph is produced by a series of analog signals, from x-ray formation and interaction with the patient, to capture of x-rays by the intensifying screen, which converts to light which produces image on the film. Digital x-ray converts the analog signal of the light to a digital signal. Converts the waves to a digital signal. Digital x-ray converts the analog signal of the light to a digital signal. Converts the waves to a digital signal.

Digital Computers Digital waveform is represented numerically by binary numbers. Digital waveform is represented numerically by binary numbers. Computer memory and storage consist of bits (binary digits). Computer memory and storage consist of bits (binary digits). Eight bits become one byte. Eight bits become one byte.

Pixels and Image Matrix X-ray beam is converted into a electronic form that is digitized and converted to squares of information known as pixels. X-ray beam is converted into a electronic form that is digitized and converted to squares of information known as pixels. The smaller the pixel, the better the image quality. The smaller the pixel, the better the image quality.

Viewing Digital Images Display Monitors Display Monitors Consideration given to size and type Consideration given to size and type Film and Paper Film and Paper Should be printed on high-quality, transparent laser film and can be viewed on viewbox. Should be printed on high-quality, transparent laser film and can be viewed on viewbox.

Digital Receptors Available in Veterinary Medicine Computed Radiography (CR) Computed Radiography (CR) Similar to traditional radiography where CR cassette is exposed, opened and image is removed from CR plate, then plate is erased and returned to cassette for reuse. Similar to traditional radiography where CR cassette is exposed, opened and image is removed from CR plate, then plate is erased and returned to cassette for reuse. Flat Panel Detectors Flat Panel Detectors Detectors in a panel that is hard wired to a computer. Detectors in a panel that is hard wired to a computer. Charged Coupled Device (CCD) Charged Coupled Device (CCD) Small flat panel that is capable of producing images from visible light. Small flat panel that is capable of producing images from visible light.

Digital Artifacts Image plate artifacts Image plate artifacts Cracks and bends in plates Cracks and bends in plates Image processing artifacts Image processing artifacts Halo effects, computer artifacts Halo effects, computer artifacts