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45 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Discovered x-rays |
wilhelm konrad roentgen, 1895 |
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ratio of x ray wavelength to visible light |
1/10,000 |
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what type of wavelength has good penetration |
short wave lengths |
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Better x-rays pass through less atomically dense particles |
true |
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matter which is penetrated by rays |
radiolucent |
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matter in which x-rays are absorbed in great measure |
radiopacity |
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Xrays which penetrate the anatomic part and produce the xray image |
remnant xrays |
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how many percent of electron energy is converted to x rays |
less than 1 percent |
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Device in which x rays are produced |
X-ray tube |
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Essential parts of an xray tube |
1. evacuated glass bulb 2. cathode 3. anode 4. tunsten ore 5. means of dissipation of heat |
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Special properties of x-rays |
1. Penetrate organic matters 2. ability to produce photographic effect 3. produce phosphoresence |
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denotes a lighter or whiter shadow on xray film or dark shadow on fluoroscopic screen |
increased density |
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implies greater penetrability by the xrays |
radiolucency |
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darker shadow on xray and lighter on fluorscopy |
decreased density |
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diminished penetrability by xray |
radiopacity |
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produced when interaction of electrons with a target atom is sufficiently violent and there is removal of inner shell electrons |
Characteristic radiation |
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A projectile electron that avoids orbital electrons but pass througu close to the nucleus. there is a loss of kinetic energy of the electron and appears as a xray photon |
Bremmsstrahlung x ray |
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Interaction with outershell electrons that scatters photon and reduce its energy |
Compton effect |
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Ionizing interactions with inner shell electrons so photons are totally absorbed |
Photoelectric effect (photon absorption interaction) |
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Basis of operation of ultrasound |
transmission of high frequency sound into the body |
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what type of modality is ultrasound? |
tomographic |
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what type of image is seen with ultrasound |
a cross section |
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3 beat characteristic of an ultrasound |
1. real time 2. no radiation 3. can provide quantitative measurement and imaging of blood flow |
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characteristic speed of sound waves in soft tissues |
1540m/sec |
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stronger echoes are returned when the beam is __________ to the structure |
perpendicular |
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High frequency waves has _____ near field and ____penetration |
longer, less |
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Low frequency has ____ depth |
deeper/greater |
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tossues that strongly reflect ultrasound |
hyperechoic |
White on film |
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Poor reflecting tissue |
hypoechoic |
grey-black |
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no sound is reflected |
anechoic, sonoluscent |
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Area behind sonoluscency that appears hyperechoic |
acoustic enhancement |
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behind strong hyperechoic object where no image appears |
acoustic shadowing |
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difference of ultrasound from xrays |
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comet tail artifact |
acoustic shadowing reverbiration artifact |
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What type of transducer to use for small superficial structures (thyroid, joints, testes) |
linear array |
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modern transducer more visualization |
curved linear |
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used for deeper orgabs such as liver spleen and kidnes. tansducer for us |
mechanical sector |
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Produce sound waves amplification, demodulation, enveloping |
pulser |
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amplifies demodulates and envelops signals and convert it to digital image |
reciever |
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transducer frequency for vascular studies |
7.5-14Mhz |
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electronic steps in returning echo |
1. amplification 2. demodulation 3. enveloping 4. processing |
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rotation of probe to 90 degrees |
cross sectional image, transverse scan |
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lying on the side |
longitudinal scan or parasagittal |
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happens when most of the sound waves go back to the probe |
reverberation |
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transducer tries to compute and put an image that is not there |
slight thickness artifact |
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