imaging midterm review

image identification

owner, patient, ID, date of examination, name, location, DVM

radiographic checklist

• Is the image labeled and legible?

• Are positional lead markers present?

• Do you have good exposure with appropriate contrast and density?

• Is your image properly centered?

• Is the body part properly positioned, with no rotation?

• Are the appropriate borders included, and is there evidence of collimation?

• Is there no evidence of a human exposure, such as a glove?

• Is the film properly processed (if applicable)?

• Have artifacts been kept to a minimum to prevent interference with the image?

x-ray tube. Cathode and anode

what is the arrow pointing at? What does it consist of?

cathode

negatively charged

anode

positively charged

stationary anode

• stays still,

• Heat is always dissipated in the same spot causing machine damage over time

rotating anode

• Disperses heat more evenly keeping dose efficacy and image quality in tact

• rotates around anode

Anode heel effect

intensity of the radiation is greater on the cathode side than on the anode side.

thicker end of animal should be placed on…

• head side

• the cathode side to take advantage of the greater amount of radiation at that end.

Line focus principle:

• describes how the electrons interact with the anode and change direction, so the x-rays are directed toward the patient being radiographed.

wall switch

• Before the on/off switch for the x-ray unit itself is the wall switch.

4 important factors involved in transmitting electicity to the x-ray tube

1. current

2. voltage

3. resistance

4. time

current (I)

• Milliamperage (MA) is the unit used to measure the electric current that activates the x-ray tube.

voltage (V)

the speed with which the electrons in the electric current transfer energy along the circuit.  High voltage (kV) produces short-wavelength/high-frequency, highly penetrating x-rays. 

resistance (R)

the factor that slows the current as it travels through a wire. A wire that is large in diameter will have low resistance. A wire that is small in diameter will have high resistance. Very large diameter or long cables that are used in the x-ray unit will “leak” electric current. This is known as line loss.

time (s)

A timer controls the length of time that the x-rays are produced. This is determined by the setting on the control panel.

different parts of the x-ray machine

x-ray tube, collimator, table, grid tray, exposure switch, cassette, generator

process of developing an x-ray

• developer

  • silver halide crystals

• fixer

  • removes unexposed silver halide, “fixes” image

• H2O bath

  • stops all processes

• dryer

PPE used during radiography

1. lead apron

2. lead thyroid shield

3. lead googles

4. lead gloves

5. dosimeters

radiopaque

metal, bone, water soft tissue

radiolucent

air, gas, fat

artifact

anything that decreases the quality of the radiograph resulting in difficult evaluation and interpretation

what does CR stand for

computerized radiography

what does DR stand for?

digital radiography

2 differences between CR and DR

• image capture method/speed

• efficiency

define latent image

the x-ray before processing

what is an automatic processor?

runs the x-ray automatically, thought developer, fixer, wash

label the bones of the front limb from proximal to distal

• scapula

• humerus

• radius/ulna

• carpus

• metacarpals

• phalanges

label the bones of the hind limb from proximal to distal

• pelvis

• femur

• patella

• fibula/tibula

• tarsus

• metatarsals

• phalanges

name of instrument that we use to measure the part that we are imaging

caliper

5 things included or performed in a diagnostic x-ray

1. positioned properly

2. x-ray centered

3. no human exposure

4. minimal artifacts

5. lead labels