Properties of X-rays/ X-ray Interaction with Tissue Flashcards
Who Discovered the Properties of X-rays?
Wilhelm Conrad Roentgen
What are the different properties of X-rays?
- Polyenergetic and Heterogeneous
- Highly Penetrating
- Invisible
- Produce Chemical and Biological Changes
- Capable of Ionizing Gas
- Produce Secondary Radiation
- X-rays Cannot be focused by a lens
- Travel in straight line and diverge a source
- Electrically and Magnetically Neutral
- Affect Photographic Film
Why are X-rays Polyenergetic and Heterogeneous?
Due to different interactions between the high speed electrons emitted from the cathode and the tungsten atoms of the anode
If 90kv is selected what will the energy level range be?
- 90 kV/3= 30
- Range will be 30-90 kV
Why are X-rays Highly Penetrating?
Due to the high atomic number of the Tungsten Target
Why are X-rays Invisible?
X-rays cannot be smelled, touched, or tasted
- Result of early pioneers suffering from radiation as safety standards were not yet set
Why do X-rays produce chemical and biological changes?
Certain chemical are known to fluoresce or glow when activated by x-rays
What chemicals glow or fluoresce when activated by x-rays?
- Barium Platinocyanide
- Rare earths and calcium tungstate phosphors
How did chemical and biological changes become apparent?
- Atomic bomb, Three-Mile Island, Chernobyl, Fukushima Daiichi
- Radiation Poisoning Erythema, alopecia, cataracts, leukemia
Why are x-rays capable of ionizing gas?
By Interaction with the outer shell electrons
What devices are used to detect the presence of radiation?
- Geiger Counters
- Ionization Chambers
What are the two different types of secondary radiation?
- Leakage Radiation
- Scatter Radiation
What is Leakage Radiation?
Radiation emitted from the x-ray tube housing in all directions other than that of the useful beam
What is Scatter Radiation?
Radiation that has interacted with atom and has been redirected in a different direction from the original path
Scatter radiation is of _________ than the ________ or __________ radiation energy
- less energy
- primary
- original
Why is it that X-rays cannot be focused by a lens?
X-rays are highly penetrating and can pass through lens making it difficult to focus the x-rays
The focusing cup in the x-ray tube only contains the _____________ to a narrower path which in turn produces __________ that are closer together as a beam
- electron stream
- x-ray photons
Why do x-rays travel in a straight line and diverge from a source?
X-ray travels at the _________.
Speed of light
Why are x-rays electrically and magnetically neutral?
Not influenced by either an electric or magnetic field
How do X-rays affect photographic film?
By ionizing silver halide crystals in the film emulsion and then processing to produce varying degrees of blackness on the film
X-ray beam consists of many energies. Who sets the controlling factors?
Technologist
In this energy level what does the 70 kV determine?
70 kV @ 5 mAs
The energy or penetrating ability of the x-ray beam
- some photons (or quanta) will have energies of 70kV or less
In this energy level what does the 5 mAs determine?
70 kV @ 5 mAs
- The amount of electrons present to produce the x-rays
- The length of time such electrons are allowed to flow
The weaker ______ will not have enough energy to pass through the body and will be _______ or _______ by tissue
- Quanta
- Absorbed
- Attenuated
Higher _______ will penetrate the bones and muscle of the body to form an image on the radiograph
Quanta
What are the two factors the influence the absorption or attenuation of x-rays?
- Thickness of the Material
- Density and atomic number of the material
Why does the thickness of material influence attenuation of x-rays?
Thick piece of material will absorb more x-rays than a thin piece of same material
Why does density and atomic number of material influence attenuation of x-rays?
Material with higher density or atomic number will attenuate more x-rays than a material with low density or atomic number
_______ attenuates x-rays so there a less x-rays to interact with the image receptor (IR) underneath the patient. It appears as _______.
- Bone
- White
______ is thin and has low atomic number so x-rays, strong, and weak, will pass through and interact with the IR to produce________ shades.
- Air
- Black
______ and________ are less dense. Stronger x-rays will pass through the object and interact with the IR, while some will be attenuated. ______ shades will be produced.
- Muscle and Fat
- Gray
