Interactive DI Seminar Flashcards
What are the 2 ways that a ventrodorsal pelvic radiograph would be taken?
– In what instances would these ways be chosen?
Extended or frogleg.
– Extended for hip scoring
– Frogleg post operatively
Why would a mediolateral view be opted for for a stifle radiograph over a lateromedial view?
Opting for the leg closest to the table is logistically better positioning wise and image quality wise. It is easier to flex the other leg out of the way.
Why would a radiograph in rostrocaudal view be taken?
To view the nasal sinuses of the nostrils next to each other.
What should be the first view of radiograph taken to x ray a thorax?
Why?
Dorsoventral
So both lungs are inflated for the best view and better assessment and interpretation.
Why is collimation important in radiography?
If the collimation too wide, increases scatter production and make the image more blurred so you get less accurate depiction of anatomy.
If collimation too tight, may cut off anatomical area of interest.
How does grid position affect the image?
An off-centre grid will absorb more of the radiation and cause the image to be under-exposed.
What may occur if the a cassette is used that has been previously used and not properly reset?
The images will lay on top of each other and it will be double exposed.
What is used in ortho radiographs to measure magnification?
A radiopaque marker. (2 radiopaque circles at each end of a radiolucent plate.
- What is the purpose of a grid?
- What exposure factor needs to be changed, and in what way, to compensate for the use of a grid? – why?
- To absorb scatter.
- mAs needs to be increased
– The grid is alternating lead slats and radiolucent slats. The lead slats absorb scatter but also absorb some of the primary beam which means that more x ray photons required to make up for the ones absorbed by the grid.
*time of exposure can also be increased.
PPE for radiation safety.
Ideally keep outside of the controlled area, then no PPE needed.
If need to be inside controlled area , e.g. to inflate lungs, inject contrast, restrain large animal (e.g. horse), need to wear protective clothing and need to wear personal dosimeters e.g. badge.
Clothing includes aprons, sleeves, neck guards (thyroid protector) and gloves and the personal dosimeter should be worn under this clothing.
What does the choice of imaging type dependent on?
Availability
Expertise in interpretation
Sensitivity/specificity of what you want to see.
Cost
Any confounding factors
- GA appropriate
- Metalwork and pacemakers (MRI).
Based on evidence, what is the best imaging modality to opt for when suspicious of FB?
Ultrasound.
Knowing what is normal when looking at imaging.
What can vary in vet med?
Species variations
Breed variations
Age variations
Body condition
Anatomical variations
What consideration must be made for the orthopaedic radiography of a young dog?
How can we be sure?
The growth plates are not ossified so may appear as avulsion fractures when they are actually normal.
Take a radiograph of the other stifle for comparison.
How can normal anatomy of the cranial thorax be mistaken for a mass or abnormality on radiograph?
The area is less radiolucent due to the lung having less air in it at this area and the lung being further collapsed by the fact the animal is in lateral recumbency. The lungs are also normally asymmetrical with the left being longer and thinner and the right pushing across to the left through the midline.. There also may be superimposition of the proximal forelimb musculature.
