Exam 2: Image Production PowerPoint III

What is Primary Radiation?

- Radiation generated at the focal spot and emitted from the tube
- cannot scatter

What is Remnant Radiation?

- image forming radiation emitted by patient and exposes IR
- contains scatter

What is secondary radiation?

radiation that interacts within the patient

What is scatter radiation?

secondary radiation that is emitted in a direction different than the tube

What path does a photon make to result in remnant radiation?

- will penetrate part and expose IR
- will have less energy than the original since it interacts with matter

What path does a photon make to result in secondary/scatter radiation?

-interacts in patient, changes direction, scatters but will eventually expose IR

What path does a photon make to result in scatter radiation?

interacts in patient, scatters, and does not reach the IR

what path does a photon make to result in attenuation?

interact in the patient and become totally absorbed

What is radiographic noise?

any radiation that interacts within the patient and interferes with the visibility

What are the types of radiographic noise?

image, processing

What results in image noise?

when the image is obtained

What results in processing noise?

during processing stage after image is taken

What is the most common noise?

scatter

What is fog?

unwanted positive density charecterized by a dull gray appearence

As fog increases what decreases?

contrast and visibility

As fog increases what also increases?

density

How can you control fog?

- using proper exposure factors
- increasing collimation
- using lead blockers
- use of grids
compression of the part

What is the amount of fog dependent on?

- tissue thickness
- bone, muscle, fat, tissue, air
- amount of kVp used
- lack of collimation

As the composition of a part increases what also increases?

fog

What is an artifact?

a form of image noise

What does positive density look like?

black

What does negative density look like?

white