MD RADIOLOGY Flashcards by Hisham Abughoush

steps of how an x-ray is made

electricity -> Heat -> electrons -> xrays

xrays produced when high speed electrons hit metal targets

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strongest to weakest light

gamma > xray > UV > visible light > infrared (UV) > microwave > radio

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visible light is carried by what?

photons

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XRAY emits a beam to the receptor. person standing in the middle between receptor and PID ( position indicating device) is called

attenuation

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give a summary of how xray works

1) electricity generates heat
2) creates electrons
3) shoot out of PID ( tube head) to the receptor
4) attenuation ( object standing between) gets hit with radiation and projects it to receptor

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what has higher energy, shorter or longer wavelength?

SHORTER (gamma)

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2 types of ionization radiation?

ELECTROMAGNETIC
: electric and magnetic field ( radio waves, gamma, xray,micro, etc: )

PARTICULATE:
atomic nuclei or subatomic particles moving HIGH VELOCITY ( alpha and beta particles)

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2 types of XRAY production ?

Bremsstrahlung ( brem: to break / rahlung: radiation)

Characteristic

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what is brehmsstrahlung ?

PRIMARY source of x ray photons

electrons strikes target and brakes giving off energy

generates CONTINUOUS spectrum of energy

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what is CHARACTERISTIC xray production

SECONDARY source xray photons

e knocks into another e and drop into lower energy orbital

emits photon of SPECIFIC energy

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what is the primary and secondary source of xray photons?

Primary: bremsstrahlung

secondary: characteristic

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what does cathode do?

tungsten filament produces electrons

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what does anode do?

tungsten target converts electrons to xray photons

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MATCH MATERIAL WITH FUNCTION:

copper / molybdenum / lead / glass / aluminum

focuses beam onto small focal spot
dissipitates heat 
insulation 
filtration 
collimation

MOLYBDENUM: focusing cup focuses beam onto small focal spot

copper: dissipitates heat
glass: insulation
aluminum: filtration
lead: collumiation

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intensity VS Energy

electrons and photons ?
how images look ?

INTENSITY
: QUANTITY of e/ #NUMBER of photons
: DENSITY: darkness of image

ENERGY:
QUALITY of e / ENERGY of photons
CONTRAST: difference in gray value

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2 images are shown side by side. the R one is darker than the L one. describe their contrast and density

Darker One: higher intensity = higher density

lower energy = lower contrast

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exposure time (s) affects what?

INTENSITY = density = darkness of image

lighter image has less exposure time which = less density

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how does exposure time correlate to photons?

more time = more photons

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tube current ( mA) effects what?

affects INTENSITY :

too much = too dark (too much photons reach sensor)

^ mA = ^ photons= ^ intensity = darker

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tube potential (kVP) affects what?

affects INTENSITY and ENERGY !!!!! bOTH

too high = too gray
too low= too light

think about it… decreasing kVP increases contrast ( LIGHTER) and increases INTENSITY ( density)

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what does filtration do to photons and involves what element ?

removes lower energy photons from beam to reduce exposure

aluminum

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which is similair to beam hardening ?

filtration
tube potential
tube current
exposure time

filtration

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collimation involved what element? how does it affect patient exposure ?

LEAD

reduces beam size to reduce exposure

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what is the best shape collimation?

rectangular

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how does distance correlate to photon emission and quality of the image?

^ distance: less photons = darker image

what is source to object distance? (SOD)

how far object is from xray source

what is object to image distance?

distance betweem object and sensor behind it

what happens to intensity when Source to object distance increases?

intensity decreases ( inverse square log)

quality of image when object to image distance gets smaller?

gets sharper

what is source to image distance ?

from xray source to sensor/film OID + SOD

what source to object distance and object to image distance do we want?

max SOD | minimum OID

what is umbra?

shadow behind an image ( no light gets to)

what is penumbra?

side shadow

how does focal spote size and penembra correlate ?

smaller FSS = lower penebra + sharper the image

why does image have poor contrast?

high kvp / low filtration

what is coherant scattering? | how does it affect contrast?

photon contact OUTER e decreases contrast !

what is photoelectric absorption? | what does it do to contrast?

incident photon contacts INNER e and forms ion pair increase contrast

what is compton scattering? | whats it do to contrast?

photon contact OUTER e and forms ion pair dec contrast

what is deterministic effect?

responses which increases in severity with increased dose . have threshold dose that needs to be met before something bad happens

what is stochastic effect?

effects that happen by chance do not have threshhold dose ( linear no-threshold model)

Direct vs inderest radiation chemistry

Direct: - DIRECTLY affecting biologic molecules ( protein,dna) - 1/3 biologic effect Indirect: - ionizing radiation converts water to FREE RADICALS alter biologic molecules (AFFECTS ENVIRONMENT SURROUNDING DNA such as salts, water, protein, O2) WHICH EFFECTS DNA 2/3 of biologic effects

which cells are more radiosensative ?

mitotically active ( sperm cells)

how many mSv is background radiation and mostly from what source?

3.1 | RADON

manmade radiation how many mSv and from what source?

3.1 | MEDICAL IMAGING

what is the average exposure to individuals living in US?

6.2 mSv ( 3.1 background + 3.1 manmade)

occupational exposure limits how many mSv per year?

when looking at radiograph and the image has radiolucent properties this means what?

R/L = dark | photons pass through tissue to reach film

when looking at radiograph and the image has radio opaque properties this means what?

r/o = light | photons are attenuated (blocked) do not reach film

what color would film be if took an image of nothing?

BLACK photons pass right through

what is film emulsion made of?

silver halide crystals

what happens during DEVOLPMENT stage of film?

silver atoms turn black

what are the 4 steps of chemical film processing?

developing fixing washing drying

during developer solution what is the first electron donor that reduces silver ions to metalic silver at latent image site ?

PHENIDONE

during developer solution, what provides an electron to reduce oxidized phenidone to origingal active state>

hydroquinone

what happens during FIXING STAGE of chemical processing >

remove undeveloped silver halide crystals from emulsion

what is the chemical in fixer solution that remove silver halide crystals ?

ammonium thiosulfate

what is PSP plates made of ?

Barium fluroihalide

what is CCD ( digital sensor dexis) made of ?

silicone

``` Film VS digital better contrast resolutin? spatial resolution? detector latitude ? detector sensitivty ( dose required to achieve standard gray level?) ```

contrast: film s[atial: film Detector latitiude : PSP Sensitivity: CCD half F speed film

fastest FIlm speed and slowest speed

fastest: F Slowest: A A B C D E F

most common radiographic error?

ELONGATION

which view to see condyles better? waters view townes view submentovertex view

townes ( angled PA Ceph of skull) | angle straight down middle of forehead

which view to see paranasal sinus? waters view townes view submentovertex view

waters ( angled PA ceph of skull) angling x-ray diagnol to back of head

which view to see zygomatic fractures waters view townes view submentovertex view

submentovortex view taking an image from floor straight up ti skull

bisecting angle techniques is when x-ray beam ray is angled in what way?

perpendicular to imaginary bisector between long axis of tooth and long axis of receptor

pano appears patient is smiling which way is his chin?

chin DOWN

what does the filament do in xray?

made of tungsten | in the cathode PRODUCE E

what does the anode and cathode produce ? what are they made of?

Cath: Electrons ( tungsten filament produces e) Anode: Photons ( tung. electrons -> photons)

what is the xray tubehead and Position indicating device?

tubehead is the bdy of the xray PID is the tube that comes off that body