Projection Geometry Flashcards
What leads to an image forming
Differential attenuations of the X-ray beam (thickness and denisty)
color for absorbed x-rays
radiopaque
color for passed x-rays
Radio-lucent
color for reflected and bent x-rays
Fogging
effect on sharpness of large vs small focal spots on an anode
Large: worse sharpness
Small; more sharp
problem with small focal spots
High heat
how we get around the problem of small focal spot heat
angle the focal spot
- increases the actual focal spot size
- small effective focal spot though
does placing the image closer or farther from the x-ray tube lead to larger or smaller
closer to the tube creates a larger image ( due to divergent
why would an objects shape be distored
Not parallel to the tube and sensor
what happens if the x-ray tube is too low
teeth look long
when happens if the x-ray tube is too high
teeth look short
benifits of a long tube
Less dense and better image (less magnifaction)
more constricted
what do you do to increase sharpness and decrease magnifcation
smallest effective focal spot
Increase distance between focal spot and object
Minimize distance between object and receptor
HOw to prevent image shape distortion
Appropriate receptor and x-ray tube alignment
- parallel to long axis of tooth
- beam perpendicular to tooth and receptor
how does the bisecing angle technique
place tube at the half angle between central axis of tooth and sensor if sensor is placed at an angle
