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RAD6608 Test 1

QuestionAnswer
who discovered the first xray.. and when? Wilhelm Conrad Roentgen, in 1895.
What were three early uses of x-ray? 1. dermatology (psorasis, ringworm). 2. hair restoration. 3. shoe fitting
What are 6 new imaging modalities? 1. CT 2. MRI 3. US 4. DEXA 5. Nuclear medicine 6. PET
What are 4 other uses of x-rays? 1. xray crystallography (DNA structure). 2. cosmic research 3. airport security 4. heavy equipment testing
What are two types of radiation types? 1. particulate and 2. electromagnetic
What is particulate radiation and what is it used for? alpha, and beta... used for nuclear medicine (BONE SCANS)
What are two types of electromagnetic radiations? 1. xray and 2. gamma
What is xray used for? for radiography and CT
what is gamma used for? used for nuclear medicine (bone scan)
visible light acts more like a ____, and xrays act more as a ____ visible light acts more as a wave and xrays act more as a particle
What are 4 atomic models... and the one we use most? medieval, dalton, thompson, and BOHR is the number one
Describe the Bohr atom nucleus with electron cloud with different energy levels (shells)
What electron shells are the most important for xray? K and L (inner two rings)
electron binding energy is dependent on what/. the type of element
More electrons = ____ binding energies higher
x-ray photons travel at what? the speed of light
in the equation C=(f)(lambda),what are each of the varibales? C= velocity, f = frequency lambda = amplitude
In the equation C=(f)(lambda) what can be modified and what cannot be changed C (velocity) cannot be changed, and lambda (amplitude) can be modified
What is photon energy directly proportional to frequency
what is photon energy inversely proportional to? wavelength
xray energy units is measured in what electron-volts (eV)
strength of xray energy units is relative to what? kVp (keV)
the field contains all strengths from ____ -- )____ setting 0-kVp setting
<10 kVp is what? crystallography
10-20 kVp is what? dermatology
30-150 kVp is what? diagnostic imaging
200 kVp - 1 MVp is what? radiation therapy
1 Mvp is what/ industrial xray
Xray charactistic moves at what? C, the speed of light
x-ray characteristic have no what and what no reflection and no refraction
xrays are unaffected by what? by electric or magnectic fields
what do xrays affect? photographic emulsion
what can xrays ionize? matter (i.e DNA)
SID? source image distance
FFD? focal film distance
TFD target film distance
SOD source object distance
OFD? object film distance
OID? object image distance
which three acronyms are the same distance?? SId (source image distance), FFD (focal film distance) and TFD (target film distance)
What two acronyms are the same? OFD (object film distance) and OID (object imagine distance)
Which films are established @ 40 inches for SID/FFD/TFD? AP cervical, apom, thoracic, lumbar, extremities, and abdomen
which films are established @ 72 inches for SID/FFD/TFD? lateral cervical, chest, full spine
What is the inverse square law? that as the distance from the source to the image receptor increases, the radiation intensity decreases by the square of the distance.
what can the inverse square law be measured in? R, rem, or mAs
What is the formula for the inverse square law? I1/I2 = D2^2/d1^2
What happens to the kVp with inverse square law? stays the same, it does not change.
@ 10 feet away from the source, your dose is <__% of the original beam 1%
what four things electricity wise does xray require? kilovoltage, milliamperage, as well as volts and amps
how much volts does xray work @? 220 V
electric current is induced if the circuit is in what? a changing magnetic field
Using ______ the 60Hz frequency of household current creates a _____ magnetic field using electromagnets the 60hz freq of household current creates a changing magnetic field
What is a transformer? a wire coil wrapped with iron core which induces a magnetic field
What is a step up transformer? More coils at the secondary side which increases the voltage
What is a step down transformer? less coils on secondary side which decreases the voltage
What is the relationship between step up/down transformers and amperage? inversely related
What is an autotransformer? a single winding, used for small increases or decreases in voltage.
What is an autotransformer used for? line compensation, since voltage can vary with other electronic use. (helps regulate voltage)
which part of the xray has the autotransformer? the operating console.
what is the operating consol used to regulate? used to regulate the line voltage to precise standards
what does the operating console increase d/t the autotransformer? increases consistency of the xray beam
What does the kVp control in regards to the xray beam? the QUALITY and QUANTITY of the xray beam (powder of in a shotgun shell)
how much does kVp move with kVp major? 10 kVp per click
how much does kVp move with kVp minor/ 1 kVp per click
the reading in the console of the kVp is actually what> volts
What does the mAs control of the xray beam? just the QUANTITY (shot in a shotgun shell)
What is the equation for mAs? mA x time
What must always be set first on the old single phase machines? ALWAYS the mAs (b/c it changes the resistance)
what are the 3 factor settings? kVp, mA and time
what are the 2 factor settings? kVp and mAs
What important factors are set on the operating console? large vs small focal spot, receiver selection (wall or table), rotor, and expose buttons.
What is the expose button aka? deadman switch
What does the rotor button do? Rotor button is pressed before the expose/deadman switch. It spins rotor up to speed.
What is an important rule about the expose button? must hold button for the entire length of exposure.
What are the values of the syncronous timer, and what hz does it use? all values are factors of 1/60, and timer uses the 60hz of supplied power for timing
What is the electronic timer? digital circuitry for timing, with better control.
What is AEC timer? Automatic Exposure Control......... ionization plate "reads" the # of photons striking the target and shits off the exposure when its sufficient.
What is the high voltage generator used for, and what type of transformer is it? used to create the high kVp needed for xray production, and is a step up transformer.
what does the transformer control with the volatge? the amplitude/size
High voltage generator wall and transformer electricity vs. xray requires what? wall & transformer is AC, and xray is DC (direct current)
What is high voltage generator electrical requirements solved with? rectification
Ac vs Dc direction? AC is bidirectional while dc is unidirectional which ensures current only travels in 1 direction using diodes
what does rectification half wave use? 2 diodes, which is wasteful b/c only half of the electrical current is used
what does rectification of a full wave use? a diode bridge//salt bridge (4 diodes) which uses the entire waveform.
what does the full wave cut in half cuts exposure time in half compared to the half wave
where in the electrical wave are xray photons produced? peak of electrical wave
the leading and finishing portions of the wave produce ___ quality xrays low
single phase power electrical wave forms @ ___hz produce what? @ 60 hz produce substantial amount of of low quality xray photons
What does three phase power of electrical wave forms produce? 3 60 hz waveforms - 180 hz effectively, therefore fewer low quality photons
What hz are high freq. electrical wave forms @? 500-25000 hz
what does high freq electrical wave forms require and result in? requires more electronics, and results in a smaller generator footprint.
high freq. electrical wave forms are more or less efficient? and offer ____ quality radiation more efficient and offer higher quality radiation
capacitor discharge generators aka? battery operated
what does capacitor discharge generators allow for? and have a large what? allows for high freq generation from 60 hz 110 V wall outlet to xray.... but has a fairly large generator footprint
What is the % voltage ripple of single phase, 1/2 and full wave rectfied? 100% ripple
what is the % voltage ripple of three phase? 4-14%
what is the voltage ripple of high freq.? <1%
ripples effects what with the xray beam? the quality of the xray beam
decreased ripple results in _____ quality of the xray? higher quality
lower quality phtons only contribute to ______, not effective ____ info contribute to pt dose, not effective xray info
how are xray unites rated? in kW
what are most xray units in kW.... and some are? most are 30 kW... some are 50 kW.
what does wattage = max mA @ 100 kVp and 100 ms
single phase units only produce ___% of the wattage of an equivalent high freq machine d/t ____ 70% d/t ripple
What are 3 dif tube types? 1. crookes tube. 2. cooldige (fixed anode) tube. 3. modern (rotating anode tube)
shoot from the ____ to the ____ cathode to the anode
does the anode or cathode create photons when electricity hits? anode
how does the xray tube housing prevent widespread irradiation? by isotropic formation of radiation
xray tube housing also prevents what, and aid in? prevents electric shock and aids in tube cooling.
xray tube is made out of??? evacuated pyrex or metal
xray tube must be a _____ vacuum
the xray tube has a thinner section of glass called the _____, which decreases ___ ____ called the window, which decreases photon absorption
Cathode aka? filament
cathode/filament side creates what? electron beam
most tubes are dual filament, with what? with a large (2 mm) and small (1mm) focal spots
large focal spots for? for larger body parts
small focal spots give better??? resolution/detial
what are filaments made out of? thoriated tungsten (W, wolffram)
thoriated tungsten has a ____ melting point, and ____ thermal expansion, and ____ vaporization high melting point, and minimal thermal expansion, and minimal vaporization
what does vaporization do? coats the inside of the tube, which leads to arcing, filament thinning and eventual tube failure.
filament current heats the ____ filament.
what is thermionic emission? which results in? electrons are boiled off (the filament), which results in an electron cloud around the filament.
what creates the space charge effect? electron cloud from thermionic emission
what is the space charge effect? hard to get additional electrion boiled off d/t the high negatie change in the cloud, and unguided the e-s would fly all over the tube, d/t inherent repulsion.
focusing cup on what side of tube? cathode side.
focusing cup// ?? Ni
what does the focusing cup// ni do? directs the e- cloud in a linear fashion toward the anode because it is negatively charged
Anode aka? target side
anode receives? and creates? receives e- beam and creates xray phtons
in what units does the anode rotate? in chiro/med xrays units and ct scanners
where are stationary anode tubes found? dental xrays
what are three functions of the anode? 1. electrical conductor 2. mechanical support 3. ***thermal dissipater.
what % of energy from xray is convereted into heat? and what % og lectrical energy produces photons? >99% goes to heat, <1% produces photons
what are the materials used for heat dispersal? tungsten target, molybdenum base and shaft, and graphite backing.
what movement helps in heat dispersal? and how so? rotation which increases the surface area over a stationary anode by 500x
____ RPM increases heat dispersal 3600 RPM
how does angling the target disperse heat? increases the surface area hit by e-s, and ****decreases effective focal spot size.
another method of heat dispersal is _____ in the tube housing oil bath
line focus principle attempts to make a _____ which is _____ attempts to make a POINT SOURCE which is physically impossible.
Created by: margaretrhager