Chapter 68 - Radiography Flashcards
What condition might cervical spinal radiographs suggest in ataxic horses?
Spinal cord compression
Which imaging technique is particularly sensitive for detecting large colon enteroliths?
Digital abdominal radiographs
What is the primary purpose of using a lead shield in an x-ray unit?
Protect the operator from exposure
What component of the x-ray tube is responsible for emitting x-rays?
Anode
What is the term for the area on the anode that is struck by electrons?
Focal spot
Which factor is adjusted to change the number of x-rays produced?
Milliampere (mA)
Exposure time (s)
What is a common limitation of portable x-ray units in equine practice?
Limited image detail
Which type of radiography system is based on using phosphorescent materials?
Computed radiography
What is the main advantage of fast intensifying screens in radiography?
Higher sensitivity to x-rays
What is the first step in processing x-ray film?
Developer step
What type of imaging is more effective for diagnosing dental disease in horses?
Which digital radiography system uses photostimulable phosphors?
Computed radiography
What causes the blackening of exposed areas on x-ray film?
Developer step
What is a disadvantage of analog screen-film radiography?
Hard copy storage
Which setting controls the maximum energy of the electrons accelerated in an x-ray tube?
kVp
What happens to the latent image on photostimulable phosphors over time?
It disappears
What is the purpose of collimating the primary x-ray beam?
Reduce radiation exposure
What is the typical maximum kilovoltage (kVp) setting for portable x-ray units?
100 kVp
What is an important aspect to consider when using screen-film radiography?
Processing must be precise
In equine practice, what is the most common use for digital radiography?
Routine limb examinations
What can radiography diagnose in the lumbar spine?
Degenerative lesions
What is an important aspect to consider when using screen-film radiography?
Processing must be precise
Which imaging technique may be required to confirm abnormalities found in cervical spinal radiographs?
Myelography
Which type of radiographic film is most suitable for high-detail examinations?
Slow/detail systems
What is the main advantage of digital radiography over screen-film systems?
It allows for post-exposure image manipulation
How does the housing of the x-ray unit contribute to safety?
It is lead shielded to protect operators
What is the role of the intensifying screen in screen-film radiography?
To convert x-rays into visible light
What must be done to the PSP after it has been used to capture an image?
To convert x-rays into visible light
Which body region is typically more challenging to radiograph?
Thoracolumbar spine
What is the effect of using a high mAs setting in radiography?
Increased exposure time
Which factor influences the resolution of an x-ray image?
A) Cathode type
B) Focal spot size
C) Film speed
What do higher kilovoltage (kVp) settings provide in x-ray imaging?
More x-ray penetration
What is the primary function of flat-panel detectors (FPDs) in digital imaging?
To convert x-ray energy into an electronic signal
Please make 40 difficutl questions and provide the correct answer about the following text:
Requires physical storage space
Which of the following describes indirect FPD systems?
A) They use a thin layer of selenium B) They require a scintillator C) They produce images in real-time
B) They require a scintillator
What does the term “real-time” refer to in the context of FPDs?
Images are displayed within seconds
Which component of the digital imaging process limits image quality?
The weakest link in the chain
What is the purpose of the acquisition computer in digital radiography?
Initial image display and adjustments
What file format is standard for medical imaging data?
DICOM
How does pixel size affect image resolution in digital radiography?
Smaller pixel size increases resolution
Which of the following is NOT a disadvantage of using consumer-grade monitors for diagnostic imaging?
A) Poor brightness
B) Lower pixel size
C) Lower cost
C) Lower cost
What is the recommended pixel size for optimal imaging in digital radiography?
B) Less than 200 microns
Which imaging method has a higher spatial resolution?
Screen-film radiography
What does PACS stand for in medical imaging?
Picture Archive and Communication System
What is a major drawback of JPEG images compared to DICOM images?
A) Smaller file size B) Lack of patient identification C) Faster processing
B) Lack of patient identification
How do digital radiographs compare in dynamic range to screen-film systems?
Digital radiographs have a vastly superior dynamic range
What impact does improper collimator calibration have on imaging?
Can result in misalignment
What technology is used in fluoroscopy to produce real-time images?
Image intensifier
What is one major advantage of fluoroscopy?
Real-time observation of dynamic studies
What should be avoided when interpreting images on a portable acquisition computer?
right environments
What is the main purpose of using petroleum jelly or Play-Doh on a hoof for radiography?
To remove gas opacities
How does the dynamic range of flat-panel systems compare to screen-film systems?
Flat-panel systems have a greater dynamic range
Which component in fluoroscopy converts x-ray energy to light?
Input fluorescent screen
What does DICOM allow in terms of compatibility?
Data compatibility across different modalities
What is a significant cost disadvantage of using medical-grade monitors?
They are significantly more expensive
What does the term “dynamic range” refer to?
The ability to produce diagnostic images across exposure values
How are images typically stored in modern veterinary practices?
On a picture archive and communication system (PACS)
Which imaging modality requires specialized viewing software to open?
DICOM
What do newer flat-panel detectors typically match in size?
Older screen-film cassettes
What effect does the brightness of standard color monitors have on diagnostics?
It decreases diagnostic accuracy
Which scintillator material is used in indirect digital FPD systems?
Gadolinium oxysulfide
What is the primary use of image intensifiers in fluoroscopy?
To enhance the brightness of the image
What is a limitation of fluoroscopy systems?
Limited penetration and resolution
Which factor should be considered to avoid distortion in radiographic images?
Keeping the tube and cassette parallel
Figure 68-1. Basic x-ray tube configuration with a rotating anode; the drawing is not to scale.
Figure 68-2. Radiographic equipment: (A) 400-speed film-screen equipment. (B) Computed radiography cassette and imaging plate. (C) AGFA computed radiography processor. (D) Sound-Eklin Mark IIG direct digital radiography system. Image plate sends the x-ray information transformed into electric signal to a computer for display.
Figure 68-3. Diagram of the internal components of computed radiography versus indirect and direct flat-panel detectors.
Figure 68-4. The large animal fluoroscopy unit from General Electric, at the Michigan State University Teaching Hospital. The x-ray tube is capable of producing high kVp and mA technique and is seen to the left of the stocks. The image intensifier, to the right, captures the x-ray information and is coupled either to a closed circuit video system or digital detection system for real-time display. The acquisition station seen to the left enables the user to see displayed images and capture them as they are taken.
Figure 68-5. (A) Caudocranial projection of a stifle with incorrect angle of the x-ray beam relative to the joint, resulting in artefactual narrowing of the medial and lateral femorotibial joint space. (B) Caudocranial projection of the same stifle with correct angle of the x-ray beam, resulting in a normal appearance to the joint.
Figure 68-6. (A) The lateromedial radiographic view of the stifle of a 3-year-old Thoroughbred gelding simulating high-mAs, low-kVp technique with film. Note that though the contrast within the bone is great, allowing visualization of trabecular pattern, the large contrast of the image makes soft tissues less visible. (B) The same radiographic view simulating high-kVp technique. Note the large numbers of grays allowing visualization of soft tissues, differentiation from fat, and the relative lack of contrast within bony structures. Note that the relative brightness of the two images is similar.
Figure 68-7. (A) A lateromedial projection of the caudal cervical spine without a grid. Note the relative poor contrast between the bone and adjacent soft tissues. (B) A lateromedial projection of the same spine, but with a 12 : 1 grid. The contrast between bone and soft tissues is improved compared with A.
Figure 68-8. Clipping artifact with a digital radiography system. The soft tissues cranial to the stifle joint are rendered black (indicated by arrow) from overexposure in this region. Note that the adjacent anatomy is normally displayed and the junction with the clipped area is abrupt.
Figure 68-9. (A) Dorsopalmar metacarpal projection using very low kVp/mAs settings showing severe quantum mottle artifact from underexposure. (B) Same metacarpus, but with moderately increased kVp/mAs settings. Note that the image is improved, but mottle remains over the thick midmetacarpal region. (C) Same metacarpus, but with correct kVp/mAs settings. Note that mottle is no longer present.
Figure 68-11. White lines travel across the image from a decentered grid. If lines occur in a regular, very closely apposed fashion, grids are usually the culprit. Note the irregular white line (arrow) along the upper right side of the image, representing hair in the cassette, as well
Figure 68-10. Lateral projection of a cervical spine, magnified to demonstrate the normal grid lines present when using a stationary 12 : 1 grid (arrows).
Figure 68-13. Dirty light guide artifact with a computed radiography (CR) system. Two parallel white lines (arrow) seen along the right side of the image are caused by debris on the light guide within the CR image processor.
