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final review prinple
| Question | Answer |
|---|---|
| date which x-rays were discovered | Nov. 8, 1895 |
| who discovered x-rays | Wilhelm Roentgen |
| 3 types of ionizing radiation | xrays, gamma rays, alpha + beta rays |
| types of radiation with enough energy to ionize a change from the normal # of electrons present, usually implying a loss of electrons | ionizing radiation |
| x-rays are part of an energy spectrum of waves traveling thro' space all around us that is known as the | electromagnetic spectrum (EM) |
| properties of x-rays | 1. invisible, no mass, no charge 2. travel at speed of light and straight lines 3. cant be focused, reflected 4. can penetrate matter any kind 5. random energy levels(from x-ray tube) 6. can cause ionization,fluorescence, similar to gamma rays |
| produced inside of nucleus and is considered what type of radiation | gamma rays natural radiation |
| produced outside of nucleus | photons |
| x-rays produced in a tube is considered to be what kind of radiation | man-made radiation |
| brems x-rays | 1.random energies 2. non ionizing 3. electron nucleus interactions @ target 4. 360 degree isotropic |
| characteristic x-rays | 1. ionizing in x-ray tube 2. specific energies 3. electron-electron interactions @ target |
| characteristics of electron | 1. have mass 2. negative charge 3. variable speed |
| characteristics of x-ray photons | 1. no mass 2. no charge 3. travel only at the speed of light |
| x-ray frequency and wavelength are _______ __________ to each other which means that the _______ wavelength x-ray photons will have ________ frequencies | 1. inversely proportional 2. longer 3. lower |
| means random directions | isotropic |
| positive electrode component of an x-ray tube | anode |
| negative electrode component of x-ray tube | cathode |
| basic function of cathode is to | produce electrons |
| basic function of the anode | produce x-ray photons |
| the filament of the xray tube is heated to boil electrons off of its surface by the process of _______________ so that they can be accelerated across the tube to give them ______________ | 1. thermionic emissions 2. kinetic energy |
| the electrons sitting around the x-ray tube | electron cloud |
| electrons move across the x-ray tube | electron stream |
| the electron cloud will never move across the xray tube unless what is applied | high (kVp) voltage |
| 3 major components of a x-ray circuit | 1. high voltage generator 2. x-ray tube 3. x-ray control console |
| diagnostic x-ray wavelength is in the range of | 0.1-1.0 A units |
| radio waves= | longer wavelength |
| all other EM radiation= | lower frequency |
| the term frequency applies to the _____ characteristics of x-ray photons | wave |
| how are xrays produced | 1.small current heats filament,frees electrons from metal by thermionic emission 2.electrons freed form electron cloud at filament 3.kVp applied send electron stream across tube 4.electrons in stream are deaccelerated suddenly,hit target,xrays produced |
| decrease in number/amount of x-ray photons as they pass through matter | attenuation |
| what are the two main physical causes that produces attenuation | 1. absorption 2. SR |
| density attenuation white | increase |
| tissue density attenuation black | decrease |
| 2 main patient attenuation factors | 1. pt. size/thickness 2. tissue density |
| abbreviations CR kvp PR FS mA I | central ray kilovolts peak primary radiation focal spot miliampere intensity |
| Abbreviations R r IP IR PACS D | Roentgen rad or rem imaging plate image receptor picture archiving & communication system |
| Abbreviation SR S RR FSS mAs mR | scattered radiation seconds or time remnant radiation focal spot size milliampere seconds milliRoentgen |
| SID OID SOD SSD | SOURCE TO IMAGE DISTANCE object to image distance source to object distance source to skin distance |
| FFD TFD OFD FOD | focal film distance target film distance object film distance focal object ditance |
| CR DR ddR HIS RIS | computed radiography digital radiography direct digital radiography Hospital information system radiology information system |
| process of x-ray production | 1.e- boiled off cathode @focusing cup 2.+ voltage added to anode side 3.e- sent to target (brems/character) 4.photons produced |
| 2 types of contrast | 1. black + white 2. greys |
| b + w have ______ contrast, ______ scale, ______ kvp, ______ latitude | 1.high 2.short 3.low 4.narrow |
| greys have _______ contrast, ______ scale, _____ kvp, _______ latitude | 1.low 2.long 3.high 4.wide |
| occurs when an incoming photon loses some but not all of its energy, then charges its direction | compton effect |
| during absorption, the energy of the primary beam is deposited within the atoms compromising the tissue. complete absorption of the incoming photon | photoelectric effect |
| incoming photon has sufficient energy to eject an inner shell electron and be completely absorbed | photoelectric effect |
| fills the void | photoelectric effect |
| photons collides with others and has an altered and scattered path with less energy then b4 collision | compton effect |
| factors dealing with the # of photons, the characteristics of these photons, & the degree of blackness produced in the image | photographic properties |
| 2 forms of photographic properties | 1.quantitative factor=density=mas 2.qualitative factor=contrast=kvp |
| changes the # or intensity of photons produced which directly influences the density of your image | quantitative factor |
| factors which change the distribution of photons reaching the IR energy, photon penetration, and varies the way that density is created in different areas of the image | qualitative factor |
| factors affecting rad image quality for photographic properties | visibility>density>contrast |
| factors affecting rad image quality for geometric properties | sharpness>recorded detail>distortion |
| those factors of image formation dealing with the fact that photons travel only in straight lines, and how the pathway of photon travels affects the size, sharpness, and shape of the image | geometric properties |
| controlling factors of geometric properties | SID, FSS, MOTION |
| the degree of blackness or conversely the lack thereof white/clear of a particular image | density |
| 2 photographic properties of an x-ray image | density & contrast |
| geometric factors deal with the fact that x-ray photons on travel in | straight lines |
| the difference between densities that allow rad information to be seen/visualized | contrast |
| in rad images, latitude is considered to be the reciprocal of | contrast |
| the ability to record the gray tones | latitude |
| refers to the sharpness of the structural lines which can actually be observed or seen in your x-ray images | recorded detail |
| radiology is measured in line pairs | resolution |
| how closely the edge of objects recorded in the rad image match the edges of the actual object | sharpness |
| the degree to which emulsion is sensitive to x-ray or light | film speed |
| the ability of rad film to provide a level of contrast | film contrast |
| double emulsion screen film is placed b/n 2 intensifying screens, which allow pt exp to decrease | film screen |
| a device found in rad cassettes that contains phosphors to convert x-ray energy into visible light, which exposes film | intensifying screen |
| has 2 screens | film screen |
| has ip plates | CR |
| cannot be adjusted | film screen |
| erased with bright white light | CR |
| trapped energy on IP "latent image" | CR |
| processing sequence for CR | 1.helium neon laser to scan IP 2.PM tube 3.ADC |
| is a 2 step process for image aquisition | CR |
| combines image capture and image readout | DR |
| uses scintillator needles | indirect conversion |
| uses amorphous SE | direct conversion |
| the sum of all rows and columns | matrix |
| a pictur element in 2D | pixel |
| a volume element in 3D | voxel |
| most important fluorescent compound that thomas edison discovered in his lab used in intensifying screens | calcium tungstate |
| the ability of a material to emit light in response to excitation is known as | luminescence |
| the form of luminescence which produces light instantaneously | fluorescence |
| luminescence with delayed light emission | phosphorescence |
| cross-section layers of intensifying screen | base,reflective layer,phosphor layer,protective layer |
| used to check for film-screen contact. blurred areas indicate loss of contact | WIRE MESH test |
| frequency distribution of pixel values within a defined area in the image | histogram |
| graphic of the exposure received to the pixel elements and the prevalence of those exposures within the image | histogram |
| provides a numerical value indicating the level of radiation exposure to the digital image receptor | exposure indicator (EI) |
| a method of altering the image to change the display of the digital image | LUT |
| alters the brightness and gray scale of the digital image using computer algorithms | LUT |
| use of absorbing materials to change the xray beam for a specified purpose | filtration |
| for diagnostic x-ray beams except for mammography units | legal filtration |
| what metal is never used in mammography filtration | aluminum |
| the glass envelope, oil, collimator mirror, etc surrounding the x-ray tube | inherent filtration |
| any absorber added in addition to inherent filtrationa | added filtration |
| diagnostic filtration requires | 2.5mm al equiv operate above 70 kvp |
| mammography requires | 0.5mm al equiv |
| filtration which is added to the x-ray beam but is not part of the legal requirements to equalize highs and lows | compensating filter |
| filtration located b/n the x-ray tube and collimator | legal filtration |
| filtration placed underneath the collimator | compensating filtration |
| is a multi-energetic or polychromatic and are used to show that the x-ray beam contains photons of may different energy levels | kVP |
| what role does kvp play in image creation | the higher the kvp the more penetration thru pt. and vise versus |
| for single-phase xray generators, the average beam energy level is about ___ to ___ of the kvp that is set | 1/3 to 1/2 |
| for three-phase or high frequency x-ray generators, the average energy level is ______ than for that of single phase | higher |
| kEV stands for | kilo electron volts |
| is synonymous with the terms mono energetic & mono chromatic | kev |
| kev denotes the energy level of a/an ________ electron or photon | single/individual |
| higher kvp produces ________ wavelengths and vise versa | shorter |
| differential absorption is greatest at ______ kvp levels | lower |
| the diagnostic range for kvp levels is | 40-150kvp |
| the thickness of absorbing material needed to reduce the intensity of radiation to 1/2 of its original value | HVL (half value layer) |
| is the absorber normally used for HVL in diagnostic testing of the x-ray beam | aluminum |
| considered to be the measurement of the beam quality | HVL |
| a normal diagnostic HVL is ___ to ___ mm of Aluminum | 3 to 5 |
| an equivalent diagnostic HVL layer is ___ to ___ cm of soft tissue | 3 to 6 |
| also known as the tube current | mA |
| mAs is the product of 2 prime factors | ma & time |
| is the total amount of radiation produced | mAs |
| using the same mAs in a x-ray exposure will produce approx=density no matter what the specific mA & time factors used to produce it | reciprocity law |
| when you change the mA on a x-ray generator what you are actually changing at that point in time is the | filament current |
| if all other factors are constant, mA & time are ______ to each other. This means if you want to use a larger mA setting, you will use a ______ exposure time and vice versa | inversely proportional shorter |
| What is the AEC role in radiography | automatically sets the exposure control factors for the RT |
| what is the effect of SID on image contrast, beam penetration, # x-ray photons produced | none |
| what is the effect of SID on beam intensity | SID is inversely proportional to beam intensity |
| What is the effect of SID on image density | SID is inversely proportional to image density |
| main function of a Grid | to prevent SR from reaching the IR |
| the grid was invented by and when | Gustaf Bucky in 1913 |
| the most effective way to remove secondary radiation from large rad fields | grid |
| Grid construction is made up | 1.grid ration 2.grid frequency 3.interspace material 4.lead strips |
| Grids are composed of ________ strips used to absorb SR, separated by ________ interspace material which allows most ____ to pass thru the grid | radiopaque radiolucent PR |
| is the radiopaque material of choice used in grids to absorb SR | lead |
| What material is used for interspace material on grids | aluminum |
| defined as the ratio b/n the height of the lead strips in a grid to the space b/n the lead strips | grid ratio |
| the most common method of defining a grids ability to remove SR | grid ration |
| the higher the ratio of a grid the more ___ and ____ that it absorbs, and the more ______ that is required to compensate for its use | SR and PR technique |
| the ______ the gride ratio the ______ cleanup | higher, more |
| the number of strips or lines per inch or centimeter is | grid frequency |
| ______ grid frequencies display _____ lines | higher, less |
| most grid frequencies are ___-___ line/inch | 60-110 |
| grids have very high frequencies, but low ratios | mammo |
| alternatives to grid use | 1.air gap technique 2.OID is increased |
| grid cut off occurs when a grid absorbs too much | PR |
| 3 main causes of grid cut off | 1.off level grids 2.off centered grids, upside down,grids used with wrong focal range 3.misangulation of the CR to grid lines |
| most modern grids today, why? | focused grids because if they are not focused they cut off the sides of the image |
| which grid ratio is the most difficult to use since it causes cut off in almost any situation where it is used improperly | 16:1 |
| the most common error made with portable x-ray exposures | off level grid placement |
| amount of technique increase which is needed when using a grid | bucky factor |
Created by:
srwiebe08