Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
PRI test 1
| Term | Definition |
|---|---|
| ___________ is controlled by quantity (amount of radiation) reaching the IR | Density |
| Can you change brightness levels? | NO. Can only be manipulated/windowed, the monitor will make it look good. EI numbers show if correct. |
| ________ has a direct proportional relationship with the quantity of xrays produced | mA |
| Double the mA= _______ quantity of xrays | doubles |
| mA controls | filament heat while time tells how long |
| Increase mA | increase heat, # of electrons produced, quantity of xrays produced and DENSITY (film) |
| What is optical density? | The amount of blackness on an image. What you see. |
| Contrast | a difference in density/ brightness levels |
| kV affects/influences | the # of xray photons and controls the efficiency of xray production. And CONTRAST!! also effects density! |
| insufficient kV what is demonstrated | quantum noise. lack of photons. |
| Subject contrast | refers to absorption characteristics of anatomic tissue (tissue thickness, tissue mass/density, atomic #) radiographed + quality of xray beam |
| Image contrast | refers to what you see on the image |
| Contrast resolution | ability of IR to distinguish between objects having similar in subject contrast |
| gray scale | # of different shades of gray that can be stored and displatyed in the DIGITAL image |
| scale of contrast | range of densities visible on FILM |
| low subject contrast | long scale |
| high subject contrast | short scale |
| spatial resolution | ability to image small objects that have high subject contrast. Anatomic details must be accurately recorded with greatest sharpness |
| distortion | misrepresentaion of size or shape of the anatomic part. |
| size distortion | Magnification! affectected by SID and OID. |
| shape distortion | misrepresentation of objects image shape. elongation or foreshortening caused by angling of IR or part. |
| scatter | unwanted exposure to IR resulting in fog (decreases image contrast), due to compton interactions. Resolution is the same just can't see it because of the fog. Digital needs collimation to reduce scatter, hypersensitivity. |
| Film= quantum ________ | mottle |
| digital = quantum _________ | noise |
| film screen imaging | limited dynamic range, no post processsing can be done, cost of film, |
| chemical film processing order and time | fixer, developer, water, dryer. time = 90 seconds |
| film density seen | 0.25-2.5. anything below too light, anything above too dark |
| digital systems | wide dynamic range (wide latitude), high EI # range |
| Who discovered xrays, what tube and when? | Wilhelm Conrad Roentgen. Crookes tube (cold cathode gassy) November 8, 1895 |
| Fluorescence | instantaneous production of light as a result from interaction of some type of energy and some element or compound. |
| Who developed first hand-held fluoroscope | Thomas Edison |
| What is xray? | electromagnetic energy with dual nature capable of ionizing tissue. has short wavelengths. |
| long wave length=______ frequency | Low. less powerful |
| short wave length= ______ frequency | High. more powerful. allow xrays to easily penetrate |
| 12 properties of xrays | invisable, electrically neutral/no mass, travel speed of light, cannot be focused, polyenergetic, ionizing, can be absorbed or scattered, produces secondary radiation, causes bio/chemical changes, travels straight lines, causes fluorescense, & chem chang |
| 3 cardinal principles | time, sheilding & distance (most important) |
| 3 requirements for xray production | source/supply of electrons, method of accelerating electrons, target to slow/stop the electrons |
| 2 target interactions in the tube | brems & characteristic. heat is by product. |
| Bremsstrahlung interactions | breaking/ slowing electron, majority of the interactions produced in radiology, below 70 kVp= 100% Brems, above 70 kVp= 85% Brems, avoids all orbital shells to get close to nucleus, energy lowers when changes direction. |
| Characteristic Interactions | Requires at least 69.5 kVp to eject k-shell electron, below 70 kVp= 0% characteristic, above 70 kVp=15% characteristic, knocks out inner/ k shell electron, ionizes atom, |
| What happens when rotor (prep button) is activated? Cathode side. | filament current (mA) heats up filament, electrons boiled off filament (thermionic emission) focusing cup keeps electron cloud together |
| What happens when rotor (prep button) is activated?Anode side. | target begins to turn rapidly, quickly reaching top speed |
| What happens after activation of the rotor and exposure is initiated? Cathode side. | negative charge repels electrons, the electrons then stream away cathode to anode (tube current) |
| What happens after activation of the rotor and exposure is initiated? Anode side. | high positive charge attracts electrons in tube current, electrons strike anode, xrays & heat are produced |
| flow of electrons= ??? | tube current, measured in mA |
| quality of xray beam = ? | penetrating power |
| emission spectrum | the range and intensity of xrays emitted changes with different exposure technique settings on the control panel |
| kV determines speed of electrons. Higher speed= higher _______ and __________ of primary beam. | quality & energy. increased xray beam penetrability. |
| What happens when kVp is increased? how does curve move on the emission spectrum? | increased photon energies of the beam. shifts up and to the right. |
| What happens when mAs is increased? how does curve move on the emission spectrum? | quantity of xrays increases. curve goes straight up. |
| what does beam filtration do? | absorbs low energy photons, reduces patient exposure |
| total protective filtration to patient =? | glass window 0.5mm+ collimator mirror 1mm+ added filters/absorbers 1mm= 2.5 mm Al Eq |
| increasing filtration | "hardens" beam, decreases quantity (low energy removed), higher quality, increases avg photon energy, DECREASES beam intensity |
| If filtration is added, how does the curve move on the emission spectrum? | down and to the right |
| compensating filters | produces more uniform exposure to IR on non-uniform anatomic areas |
| What is wedge filter used for? | foot, femur |
| what is trough filter/ double (bilatera)l wedge used for? | thorax |
| Anode heel effect | xrays more intense on cathode side of xray tube. intensity of xrays decrease toward anode side. think FAT CAT! |
| Line focus principal | relationship between actual and effective focal spot |
| actual focal spot | area on anode target exposed to tube current electrons |
| effective focal spot | focal spot size as measured directly under anode target |
| smaller anode angle= ? | smaller effective focal spot size |
| Heat units (HU) | HU=mA x time x kVp x generator factor |
| How to extend xray tube life | warm up tube, avoid excessive heat generation, don't hold rotor button if not exposing, use lower mA and longer exposure time, don't move tube while energized, recognize unusual noises and report |
| process of image formation is due to __________ __________ of the xray beam as it interacts with anatomic tissue | differential absorption |
| xray absorption of anatomic tissue is based on what? | composition (atomic number and tissue density). eg. bone absorbs more xrays than muscle |
| As the primary beam interacts with anatomic part, photons are? (3) | 1. abosrbed (photoelectric effect=white) 2. scattered (compton interaction=fog) 3. transmitted (w/o interaction=dark/gray) |
| attenuation definition | the total reduction of # of srays remaining in xray beam after penetration through a given thickness |
| attenuation = _________ and ___________ | absorption and scattering |
| Photoelectric interactions= _________ of xrays. And they appear ________ on an image. and interacts with what shells? | absorption, bright/white, Kor L-shell (ionization occurs) |
| compton effect/scattering interacts with what shell? | outer shell electron. |
| 4 factors affecting beam attenuation | tissue thickness, type of tissue, mass-tissue density, xray beam quality |
| tissue thickness: xrays are attenuated exponentially and reduced by _____% for each _________ cm of tissue thickness | 50% and 4-5cm |
| type of tissue | tissue composed of higher atomic number will increase beam attenuation. eg bone absorbs more than soft tissue |
| mass- tissue density | increased compactness of anatomic particles will increase beam attenuation |
| xray beam quality | higher kVp increases xray energy and will decrease beam attenuation.(shoots through tissue rather than getting absorbed) |
| exit = image-formation= remnant radiation is? | composed of transmitted and scattered radiation |
| Visibility factors | brightness and contrast |
| sharpness factors | spatial resolution and distortion |
| factors affecting radiographic image quality | visibility and sharpness factors |
Created by:
jveliz91
Popular Radiology sets