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rad 100- ch1
| Question | Answer |
|---|---|
| Attenuation | Process by which a beam of radiation is reduced in energy when passing through tissue or other materials. (Change of energy) |
| Computed Radiography (CR) | The x-rays strike a phosphor plate (PSP) inside a cassette. The cassette is then taken to a separate reader, which scans the plate to create the digital image. 2 step process (analog-->light-->digital) |
| Digital Radiography (DR) 2 subsets | Digital image acquisition systems that convert x-ray energy into a digital electronic signal for manipulation and display using direct or indirect conversion. |
| Direct conversion | (DR) Uses 1-step process, no cassette. The x-rays strike a detector, which directly converts the signal into a digital image that is sent to a computer. |
| Indirect conversion | (DR)X-rays strike a scintillator material, which converts them into visible light. A photodetector, often an array of amorphous silicon photodiodes, captures this light and converts it into an electrical charge. 2 steps. cassette. |
| Scatter radiation | X-ray radiation that spreads out in different directions after interacting with a substance, such as body tissue |
| Primary radiation | X-ray beam after it leaves the x-ray tube and before it reaches the object |
| Absorbed radiation | When an X-ray passes through the body, tissues like bones absorb more radiation than soft tissues, which is how the image is created. The absorbed radiation is the energy deposited in the tissue |
| Remnant radiation | Radiation resulting after the x-ray beam exits the object |
| Differential absorption | Different materials absorb radiation energy differently base on its density and atomic number. |
| High Attenuation occurs in _____ matter | denser. radiopaque (appears white as it is denser tissue) Ex: bone, muscle |
| Low attenuation occurs in ______ matter | less dense. radiolucent (appears dark on Xray as it is lower density) Ex: air |
| What kind of plate does computed radiography use? | PSP- photostimulable phosphor |
| What photoconductor is used in direct conversion? | Amorphous selenium |
| What photoconductor is used in Indirect conversion? | Amorphous Silicon |
| Who discovered X-ray? | Wilhelm Roengen (renkin) on Nov 8, 1895. took image of his wifes hand. |
| Father of western medicine | Hippocrates |
| What is radiography | using energy to take an image. |
| 7 types of energy for taking images | ionized (radiation), sound, heat, radio waves, magnetic, nuclear, electrical |
| What type of radiography uses gamma radiation PET scans | nuclear |
| CVIR | cardiovascular interventional radiography, angiography. uses x rays, injects catheter and contrasts. |
| DEXA scanning | bone density scanning |
| kV range for tube | 50,000-120,000 kV |
| IP | imaging plate. reusable for thousands of images |
| IR | image receptor. Device used to capture the image for recording, such as photo-stimulable phosphor imaging plate or a digital flat-panel detector |
| receiver | aka the Image receptor (IR). device used to capture the image. Plate |
| F-centers | IP are composed of a layer of barium fluor halide crystals. These crystals store the dose of energy from the x-ray. They are later activated with a laser to produce light and that creates the image. |
| Pixel | Picture element and the smallest component of the matrix |
| Flat panel detector | cassette. FPD- photo conducting panel/ can be made of amorphous selenium or amorphous silicon |
| The primary radiation is attenuated by what 2 mechanisms? | scatter and absorbed |
| How does an x ray work | radiation is passed through matter(the pt) and strikes an image receptor. The IR converts the energy into an electronic data set. |
| underexposure will cause an image to be___ | grainy or noisy |
| Which class of radiography uses scintillators? | Indirect digital radiography. |
| What two things are a function for image quality? | X-ray exposure (energy amount and parameters) and Image receptor characteristics (the patient) |
| tube envelope | Vacuum |
| filament | Source of electrons |
| Voltage | Method to accelerate the electrons rapidly |
| Method to stop the electrons | target |
| Scintillator | detector that emits light after struck with the xray. Turns xray photons into light, then the light will be turned into electrical signal. Electrical signal creates digital image |
| Main difference between direct and indirect conversion | (digital rad) direct conversion plate receives the photons and directly converts them to an electrical signal. Indirect conversion uses a scintillator to convert the photons to light and then to the electrical signal. Adds another step. |
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