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oral radiology D2 > exam1 > Flashcards

exam1 Flashcards

1
Q

What type of raidation is x-radiation?

A

x-radiation is a form of EM (electromagnetic) radiation – the entire EM spectrum is considered EM radiation.. travel as photon (quanta) in waves. weightless. no electrical charge. (( the only other type of radiation is particulate (corpuscle) radiation and involves things like protons, neutrons, electrons, aplha and gamma particles

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2
Q

what are the two types of radiation?

A

the two types of radiation are EM (electromagnetic) and particulare (corpuscle) radiation.

X rays are a form of EM radiation (in the X-radiation wavelength spectrum.. and like all EM waves.. the wavelength is associated with energy content as is frequency of the wave.)

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3
Q

What are the 2 components of radiation?

A

The two components of radiation are its 1. production (production of the radiation form), and 2. emission/transmission of energy

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4
Q

T/F Radiation is defined as the production and emission of energy through space or a material medium

A

True. Radiation is defined as the Production and Emission of energy through space Or Material medium

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5
Q

T/F Diff types of EM wave have different values of mass and electrical charge

A

False. The different types of EM waves have the same ‘value’ of mass and electrical charge = NONE

EM waves have no mass and no electrical charge and travel in a wavelike motion (but travel as quanta)

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6
Q

How is wavelength indicative of energy content?

A

Longer wavelength = less energy while a shorter wavelength means higher energy. This is an inverse relationship bt wavelength and energy content of an EM wave

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7
Q

Put the types of waves in order of their wavelengths from long wavelength to short wavelength::

microwave, ultraviolet, xray, infrared, visible, gamma ray, radio

A

From longest wavelength (and therefore Least amount of energy) to shortest wavelength (hgihest energy)

radio, microwave, infrared, visible, ultraviolet, xray, gamma ray

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8
Q

Are the emitted xrays from a single source of heterogenous or homogenous energy characteristics?

A

emitted xrays (from a single source) have heterogenous energy characterisitcs in that they possess a range of energies and therefore a range of wavelengths. however, they are all still of EM radiation characteristics (weightless, no electrical charge)

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9
Q

X-rays cause —- in biological molecules

A

Xrays cause IONIZATION in biological molecules (knock off e- from the nucleus

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10
Q

Xrays are produced when a fraction of the –potential/kinetic– energy of –high/low– speed electrons is converted to x-radiation

A

X rays are produced when a fraction of the KINETIC energy of HIGH speed eletrons is converted to x-radiation

–input electricity generates electrons that are produced at a low-voltage cathode (negative charge)(tungsten filament supplies the e-).. then electricity (push of button@clinic) supplies the anode w high voltage. this potential difference bt the high and low voltages attracts the highenergy e- to the anode (+) which has a tungsten filament.. these electrons strike the anode.. 70%bremsstralung where the incident electrons strike the nucleus or nearby K shell e-.. 30% is characteristic radioation whenre the incident e- interact w e- of the target (tingsten) .. the interaction knowcks a target e- out of orbit.. an outer electron fills the space abandoned by the ejected electron.. this drop from high energy to low neergy releases energy in the form of photon– and at high energy photons of the xradation spectrum = xrays

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11
Q

Which particle of an atom determines the identity of the atom?

A

The proton determines the identity of the atom. Each different number of protons in the nucleus is a different element.

the number of protons of an atom is its ATOMIC NUMBER (Z) = the subscript written next to the chemical symbol of the element

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12
Q

The magnitude of charge between protons and electrons is what ratio?

A

The magnitude (absolute value) of charge bt p+ and e- is 1:1. The magnitude of postive charge of proton is equal tot he agnitude of negative charge of the electron.

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13
Q

What is atomic mass?

A

Atomic mass= the mass of an atom as determined by adding hte number of protons and neutrons in the nucleus of the atom. Neutrons are slightly heavier than protons, but no by uch (so treated as equivalent). And, electrons have such a tiny weight that they are negligible and not factored into mass calculations

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14
Q

What is the maximum # of orbits in any given atom?

A

The maximum # of orbits in any given atom is 7, or the Q shell.
K (2), L (8), M(18), N (32), O, P,Q (980.

recall, these shells have spdf.. subshells.. etc

electrons certain orbits possess energies associated with their occupied shell ((closer to nucleus = less energy in electron itself, but greater binding energy = effort to separate the electron fromt he nucleus ……. while, further from nucleus = higher indiv electorn energy, but lower binding energy bc easier to remove the outer electron from the atom (nucleus has a weaker hold on outer electrons/

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15
Q

Electrons in which atomic shells are involved in xray production?

A

Electrons in the K,L,M shells are involved in xray production.. these are the shells closest to the nucleus and possess the highest binding energy (( binding energy = the amount of energy needed to overcome in order to remove the specific electron from its orbit)

electons in the outer shells (M->Q) are invovled in the production of other EM waves- like visible, UV, etc

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16
Q

T/F The hgiher the Z#, the higher is the binding energy for any particular shell

A

True. The higher the Z#, the hgher is the binding energy for any particular shell.

Z# = the atomic number (identy, # protons, higher Z number is a heavier atom) . higher Z # = more postiive pull power = holds electrons tighter and attracts further orbits.. so more power = more difficult to dislodge the electrons so = higher binding energy

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17
Q

What does ‘Linear Energy TRansfer’ refer to, and with what type of radiation is it associated?

A

Linear Energy TRansfer(LET) = particulate radiation = is the energy lost of the radiation particle as it moves along its path to an absorber

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18
Q

what are the two types of rdiation emission/transmission?

A

Paticulate and non-particulate and the two types of radation emission.transmission

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19
Q

What kind of energy is associted with particulate radiation?

A

Kinetic energy is associated with particulate radiation

kinetic energy is descrbied by (1/2) x mass x velocity(^2).. so the amount of kinetic energy is directly related to mass and velocity .
more mass more velocity = more kinectic energy

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20
Q

T/F Particulate radiation is common to diagnostic therapy

A

Fasle. Diagnostic xray therapy is the production of radiographs.

Particulate radiation is common to radiation therapy.. this is where the higher mass particles stay within the target tissue to kill tumors, etc///

Diagnostic therapy uses non-particulate radiation that does not lose its energy fast and can tranverse the absorber material and hence reach the recorder film to register as a diagnostic image).

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21
Q

According to the linear energy transfer rule::

higher mass particle = higher (faster) rate of energy transfer. so, heavier atom- loses energy, (will not traverse absorbing maerial)

the higher the charge, the faster the rate of energy trnasfer “” so if ionized, the particle will travel less distance is absorber bc loses its energy quickly (convesey, EM nonparticulate radiation is weighltess so is able to traverse the absorber)

the higher the velocity, the slower the rate of energy transfer (the higher the velocity, the particle travels further in the absorber- so retians energy longer = slower rate of energy transfer)

the absorber material: the denser/thicker the faster the rate of energy rtansfer (the less the particle can travel/penetrate)

A

true.

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22
Q

Are xrays particulate or non-particulate radiation?

A

X rays are nonparticulate radition – they are weightless (no mass) and have no charge.

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23
Q

Put these forms of radiation in order of their distance of penetration into tissue from penetrates the least to most:

beta, alpha, x ray

A

tissue penetration least to most:
alpha < gamma, xray

BOth alpha and beta raidation are particulate radiatio = alpha and beta particles. alpha particles are heavier – and therefore penetrate less than the gamma particles (according to the liner energy transfer rule) . X rays are nonparticulate radiation.. are weighltess and therefore travel the furthest (lose their energy the least) and penetrate the tissue the most – hence able to reach raditograph receptor film and register a diagnostic image

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24
Q

How do both the wave theory and the quantum theoey describe electromagnetic waves?

A

Electromagenetic wave properties are described bith by the wave theory and the quantum theory.

the wave theory asserts that EM radiation travels as waves.. this is true.

the quantum theoery asserts that EM raidation travels in bundles of discrete nergy– called phtons or quanta … this is also true.

so, little discrete bundles of energy called photons travel in a wave.

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25
Q

Is electromagnetic radiation associated with particles?

A

No. Electromagnetic radiation is not associated with particles. Electromagnetic radiation is non[articulate radiation

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26
Q

T/F EM radiation is emitted in all 360^ directions from the source

A

True. EM raidation is emitted in all 360^ from the source..

in clinical xrays (ex/ diagnostic) there is a focusing cup (of molybdenum) that directs the generated rays towards the pt/.target

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27
Q

what unit of measurement are xray wavelengths measured?

A

Xray wavelengths (lambda) are measured in the atomic uni of Angstrom

1 angstrom = 10 x 10(^-10) meters

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28
Q

T/F the velocity of all EM radiation in air is the same

A

True. the velocity of all EM radiation (inc X rays) is the same in air! = c = wavelength (lambda) x velocity (mu) = a known value:: 3 x 10^10 cm/sec

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29
Q

what is frequency?

A

frequency is the number of oscillations/vibrations/eaves/cycles per second

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30
Q

what is the speed of xrays in air?

A

the speed of xray in air is the same as the speed of all other form of EM raidation in air: aka the speed of light aka 3 x 10^10 cm/sec (186k mi/sec)

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31
Q

In EM raidation (EMR) would you expect waves of higher energy to have a higher/lower velocity? and longer/shorter wavelength?

A

In EM radiation. it is not particulate so mass is not a factor in descrbinging energy contnect… instead.. frequency, wavelenth, velocity are indicative of energy content.

for higher energy there would be
higher velocity
shorter wavelength
higher frequency

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32
Q

T/F Oral and maxillofaical radiology is a specialty

A

True. Oral and maxillofaical radiology is the specialty of dentistry and discipline of radiology concered w the production and intrepreation of images and data rpoduced by all modalities of radiant energy that are used for the diagnosis and management of diseases, disorders, and conditions of oral and maxillofacial ragion

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33
Q

Name the 2 subcategories of radiology

A

Radiology is split into therapeutic radiology and diagnostic radiology

thereapeutic radiology is commonly particulate radition (alpha, gamma).. where the particles are of high energy but lose energy fast within the tissue.. are more ficused to target and directed to kill tumor

diagnostic radiaology involves xrays = EM, nonparticualte energy.. these traverse the tissue and register on film to create a diagnostic image

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34
Q

when were xrays discovered and who discovered them?

A

Xrays were discovered in 1895 by Wilhelm Roentgen. Hence, radiology synomyn w roentgenology, roentgenoprah, etc.

Roentgen worked with cathodes and produced the cathode of the xray tube

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35
Q

Who took the first oral radiograph?

A

The denstist Dr. Otto Walkoff took the first oral radiograph soon after Roentgen discovered them in 1895. Dr. Walkoff took the radiograph of his own mouth w/ 25 minute exposure

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36
Q

How long (approximately) is xray exposure during diagnostic radiation in dental offices

A

Diagnostic radiation exposure is less than a second (tenths of a second) in the clinical (dental) setting

37
Q

Who was the first doctor to recognize the use of radiographs as a diagnostic tool?

A

Dr. C Edmund Wells of New Orleans was a dentist and he first recognzied and utilized radiology as a diagnostic tool.

However, safety precaustions were not yet knwn and Dr. Wells eventually lost fingers, arms, and his life due to overexposure

38
Q

What company is credited with developing the first commerically used dental xray unit?

A

Siemens corporation is credtied with developingthe first commercially developed dental xray unit– the design is still very similar today (( on a tall arm with a mobile arm unit)

39
Q

What is William D. Coolidge credited with?

A

Coolidge is credited with improving the quality of cray radiographs throught he devlopment of the hot cathode tube (in 1940)

later develpments = xray film varieties, digital, panographic, CT scanner MRI..(tesla) cone beam

40
Q

T/F different tissues have different amounts of radiosensitivity

A

True/. Differnt tissues exhibit differnt amounts of radiosensity (and certain qualities make cell types more susceptible too.. nand cells make up tissues, etc)

41
Q

who is considered to be the father of radiation protection?

A

Dr. William Herbert Rollins DMD is considered to be the father of radiation protection

42
Q

T/F patients have many concerns regarding xrays

A

True. Patients have many concerns regarding xrays – such as the biological impact of the xray, pregnancy impact, the number of xrays.. etc..

43
Q

T/F The dental field does not commonly use radiology technologies

A

False. The dental field commonly uses radiology - in diagnostics.

  • dental radiographs are 2nd most taken xray and 2nd in cost of xrays taken.. (1st = chest)
  • 1/2 of all xray units in us are dental
  • apprx 300million dental xrays year/worldwide
44
Q

T/F The biological effects of radiation are divided into 3 categories.. deterministic, intermediate, stochastic

A

False. The biological effects of radation are divided into 2 categories: deterministic and stochastic

45
Q

Having a ‘dose threshhld’ is characeristic of which type of radiation biological effect?

A

The DETERMINISTIC type of biological radation effect has a Dose Threshhold– this is an increment of radiation that is tolerated before any biological effects occur.

– ex, radiation sickness, acute effect, oral changes after radiaotherapy (less saliva produced, oral epithelia impacted)

stochastic biological effects do not have a dose threshld.. any amount of radiation has a correlated effect of more chance of radiation impact (( all or none finality.. but more radiation increases chance for all-or-none impacs..)
–ex. radiation induced cancer or mutations

46
Q

with deterministic effects, the more the radiation dose, do we expect more/less/same severity o response (in form of amount tissue damage)

A

with deterministic bioloicl radiation effects, there is a directly proportional relationship bt raidation dose amount and severity of response amount:
– somatic effects, acute effects = deterministic (not genetic)

more radiation increases the amount of tissue damage (therefore a more severe outcome with more radiation)

47
Q

radiation induced cancer and radiation induced mutations are examples of what kind of biological radiation effect?

A

The formation of cancers and mutuations is an all-or-none impact exemplory of stochastic biological effects of radiation. stochastic effects have no dose threshold.. and severity of the damage does NOT correlate with amount of radiation.. however, tjhe CHANCE of the all-or-noting impact of varying severity Increases with increaed exposure to radiation

48
Q

T/F stochastic effects have a severity directly proportional to amount of radiation exposure.

A

False. Deterministic biolofical effects of radiation have a directly proportional amount of severity to raidaiton exposure – more damage results from more radiation.

with stochastic effects, the CHANCE of damage directly increases with increased radiation. More radiation= more CHANCE of damage. The amount of damage itself is Independent/ not correlated w the amount of radiation.. only the chance of occurence is dependent of amount raidation. The occurene is cancer or mutation and is all-o-nothing

49
Q

T/F Deterministeic effects of ionizong raidation include short-term, acute injury

A

True. Determinisic effects of ionizing radiation include short -term, acute injury. (( deterministic = somatic effects, such as radiation sickness, changes in oral epithelium and mucosa… ))

50
Q

Which of the following are impacted by ionizing radiation?

biological molecules, cell struvutrues, cell cycle, tissues and organs

A

All. biological molecules, cell strctures, the cell cycle, and on a larger scale tissues and organs are all impacted by ionizing radiation

51
Q

T/F ionizing radiation causes both direct and indirect effects on biological molecules

A

True./ Ionizing radiation has both direct and indirect effects on biologcal molecuels.

direct effects include – free radical production, and radiolysis of water (produces hydrogen peroxide which is harmful to bio molecules) /// leads to ionization, dissociation of molecules, and cross-linking. is 1./3 of biological effect

indirect effects – also produces free radicals, is 2/3 of biological impact

52
Q

what does radiolysis of water produce?

A

radiolysis of water by a photon ionizes the water into unstable parts of H and OH, which react w neighobrs to start a chain of hydrogen peroxide formation H2O2, which is harmful to bio molecules.

indirect effects involve the split H and OH interacting w biological moelcules and produces biolofucal free radicals

53
Q

what are some indirect effects of radiation on bio molecules?

A

The direct effect involves radiolysis of water that produces H and OH ions that are unstable. These components interact with neighbors (direct effect, form hydrogen peroxide H2O2) and indirect interacts w biolofical molecules.. and create biological free radicals by stripping the bio molecule of a hydrogen and leaving i as a bioloical free radical == unstable biiolocal molecule
***2/3 of biological effects of radiation are of the indirect type

54
Q

Are direct of indirect effects of radation more prevalent in damage to biological molecules?

A

The indirect effects of raidation (where free radical bio molecules re created) account for 66% (2/3) of the effects of radation on bio molecules– so the indirect effects are more prevalent than the direct effects (make H2O2 hydrogen peroxide)

55
Q

Is this an accurate statement?

The effects of radiation on cell strucutres includes chromosomal breaks, vacuolization, mitotic changes, impaired function.. and will ultiamtely lead to cell recovery or death

A

True. Radiation results in all :

  • chromosomal breaks (likely direct/indirect impacts).. single stranded breaks are easier to repair than double stranded breaks 9and both types exist!)
  • vacuoliation – this is the appearnace of vacuoles in a cell, and in indicative of cell damage - cells form vacuoles when they are damaged.. a part of cell biology
  • mitotic changes– cells are more sensitive in certain stanges of cell division vs. others .. cells esp sensitive in G2 and M(division) stages,
  • impaired func – free radicals destroy the machinery of a cell

and ultiamtely the cell will wither recover or die

56
Q

T/F impacts of ionizing radiation on the cell cycle include mitotic delay or cell death

A

True. the ionizing impcts of radation on the cell cycle include mitoic delay and cell death. the cell at different stages of the cell cycle is more sensitive to radation. radation during sensitive stages leads to cell death, while radiation during less sensitive stages results only in mitotic delay

((recall, cell cycle: G1 arrest/gap, S- dna synth, G2 gap, mitosis M actual division))

  • G2 and M are radiosenstive while G1 and S are less sensitive
  • Radiation during the sensitive stages of the M or G2 phase result in cell death
  • Radiation during less sensitive stages of G1 arrest and G2 block results in mitotic delay int he cell division
57
Q

Put these cell cycle stages in order from most to least radiosenstive:

M,S,G1,G2

A

Ordered from most to least radiosensitive:

M, G2, G1, S
most —>least radiosensitive

58
Q

The sensitivity of a tissue parenchymal cells determines the short or long term effects of radiation on tissue?

A

The sensitivity of a tissue’s parencymal cells (functional) cells to radiation is a SHORT TERM effect determinnant.. aka parenchyma cells correspond to short term radiation efects

59
Q

T/F long term radiation efects depend primarily on the extent of damage of fine vasculature

A

True. Long term radiation effects depend primarily on the extent of damage on the fine vasuclature of hte tissue

60
Q

According to the law of Bergonie and Tribondeau, what 3 properties describe cells that tend to be radiosenstive?

A

having a high division rate, a long dividing future, and being undifernetiated (unspecialized) are 3 characterisitics that render a cell radiosensitive.

so, stem cells are radiosenstive.. as are rparative cells (ex- those of the oral mucosa, oral gingival.. etc)

61
Q

are neurons and muscle cells consdiered to be radiosensitive or radioresistant?

A

neurons and muscle cells are on the radioresistant side of the sensitivity spectrum and most radioresistant. ..

stem cells, the basal layer of oral mucosa both represent members ont eh opposite side of the spectrum- the most radiosensitive

62
Q

overall, tissues and rogans can be grouped into 3 categories representing high, intermediate, and low radiosensitivities. organize the following items into the types:

lungs, kidney, testes, intestines, muscle cells, lymphocytes, growing bone, mucous membrane, optic lens, fine vasculature, mature erythrocytes, neurons, bone marrow, salivary glands, liver

A

Think: most highly replenishing, stem-cell like have the highest radiosensitity, while muscle and neuronal cells are most radioresistant:

High radiosenstivity: Bone marrow, lymphocytes, mucous membrane (oral, intestine), intestinces(recall, high turnover), testes (gametes!)

intermediate sensitivity: fine vascualture (damage here has long term impct), salivary glands (+imapct of mucusu membrane, salivation imnpacted by radiation), lungs, kidneys, liver, growing bone

low sensitivity: neuronss, muscle cells, mature erythrocytes ((recall, no DNA!))

63
Q

for discussion of manitude, is 1000 Gy considered to be a lot of radiation?

A

YES! 1000 Gy is an absurdly bg amount of radiation. 100 Gy is enough to kill someone from neuro and cardiovascualr breakdown within hours of exposure.. dental radiographs are taken on the order of micrograys.
*1gray = 1sievert ((siervert = term for x and gamma rays))
1 gray = the amount of radiation abosrbed by 1 kg of matter

64
Q

If given a dose of 5 gray radiation, is death a possible acute impact of exposure?

A

Yes. Given a 5gray (= 5 sievert, Sv in xrays) exposure, death is a possible acute impact. Death would be expect within several weeks due to damage to bone marrow (hematopoeitic syndrome) ..

more radiation to 12 gray would preceipiate death to occur within days due to damage to intestiinal tissue resulting in bloddy diarrhea (gastrointestinal syndrome)

increasing raidaitonin up to 100 Gy results in death within hours due to destruction of neurons and vasculature

1 sievert results in radiation sickness

dental radiography in order of micrposieverts (10^-6)

65
Q

What is the general magnitude of radiation exposure delievered by dental radiographs?

A

Dental diagnostic radiology delivers eradiation in the magnitude of micro (10^-6) sieverts.

1sv = 1gray .. = the amount of radiation absorbed by 1 kilogram of mass. sievert, sv = a term for xray and gamma radiation types specifically.

66
Q

what is the most important somatic effect of radiation?

A

Cancer. radiation can induce the formation of cancer (due to impact and damage to biological molecules).. this is the most important somatic effect of radition.

genetic effects of radiation are undocumented with diagnostic radiation and only seen in survivors of the atomic bomb

67
Q

organize the following into CANCER susceptibility of the tissues:: high, moderate, low::

breast, liver, bladder, thyroid, stomach, esophagus, colon, lung, skin, cortical bone, bone marrow, brain, salivary glands.

A

less obvious organization::

most cancer susceptible tissues:
colon, stomach, lung, bone marrow

moderate susceptibility to cancer:
breast , esophagus

low susceptible to cancer:
skin, salivary glands, cortical bone, brain, thyroid, liver, bladder

68
Q

what is alara?

A

Alara is an important concept that guides practitioners in the use of radiology:: alara is a concept created by the ICRP (international council on radiation protection)..

ICRP recommends:

1) no practice shall be adopted unless its introcution produces a positive net benefit
2) all exposures should be kept as low as reasonably achievable
- the dose equibalent to individuals should not exceed the limits recommended

69
Q

T/F It is okay to not keep track of patient radiation exposure

A

False. it is important to keep track of pt radiation exposure… there exist limits on what is indivually ‘safe’, further, other sources of radiation exist, the effecs of raidation are addtive (more radiation ..over a lifetime = more damamge, more chance of damage) etc. must be aware of radiation use

70
Q

what are the two main sources of natural radiation?

A

We are exposed to radiation just being out and about. outer space and the soil are the two biggest antural rdiation sources. (radon in the soil) just eating a banana = 75 microsievert bc of soil impact..

71
Q

what are the national and international values of occupational limit (effective dose) of radiation

A

International and national (US) vlaues are the same for occupational limit (effective doese) of radiation:
= 50milliSieverts

non-occupational limits call for 5mSv in the US and only 1 mSv according to international recommendations

72
Q

Are children more/less/the same sensitive to radiation as compared to adults

A

Children are more sensitive to radiation than are adults. Both, children are younger, AND children live for longer so experiene more build up via ADDITIVE effects of radiation

children = 2x as radiosensitive as adults

73
Q

Radiation can excite and ionize. What is the difference?

A

Excitiation is when the energy of the incident ray (eith xrays = the incident electrons) is less than the binding energy. so the recipeint atomic electron absorbs the incident electron energy as KE.. is excited out of its orbit, then quickly releases the extra energy and returns to its home orbit.

Ionization is when the incident energy is greater than the binding energy holding an electron in orbit, such that the atomnic electorn is ejected out of orbit and takes on the incident energy as Kinetic energy 1/2mv^2. the usefulness xrays is dependent upon its ionzing attribute

as such, ions are created.. the atom loses its orbital electron and becomes a + charge ion, while the ejected electron is negatively charged

74
Q

are xrays a type of particulate radiation?

A

No! xrays are electromagnetic EM radiation NOT praticulate radiation

75
Q

With the following conditions, are ionizing xrays More or Less able to penetrat the target tissue?

Higher photon energy
Fewer photons/incident electrons
Thick, dense absorber

A

Higher photon energy results is greater ability to penetrate target tissue/material

  • fewer photons/ fewer incident elctrons results in LESS ability to penetrate tissue
  • a thicker, more dense absorber/tissue will result in LESS penetration by xrays (conversely, less dense = more penetration.. for example, the cranial sinuses are air and 100% traversed by xrays)
76
Q

What is kDP?

what is milliamp?

A

KDP is the amount of energy posses by a photon. bigger kDP = more energy of photon

milliamp = the # of photons present ((recall, a user modificalbe setting is the milliamp of the xray machine.. more milliamp creates more electrons at the cathode.. more incident electrons and therefore more photons result) more milliamps = more photnss= more penetration

77
Q

xrays can cause fluroescnes in certain crystals..why is this helpful?

A

the fluorescnet effects of xradiation are useful in intesifying screens

78
Q

which way do positive electric fields deflect xrays?

A

Xrays are NOT delfeted at all by electric or magentic fields. Xrays are neutral and have no charge.

79
Q

Are xrays capable of ionizing gases?

A

Yes. Xrays are capable of ionizing gases. The ionization attirubute of xryas is crucial in using i as a diagnostic tool

80
Q

what is the speed of an xray through air?

A

Xrays travel at the speed of light – 3x 10^8cm/sec

all forms of EM waves travel at the same speed through air

81
Q

what is the useful wavelength range for dental radiology

A

xrays with wavelengths bt 0.1 and 0.5 Angstrom are the useful range (and therefore energy content) for dental radiology

82
Q

T/F high energy X rays are common for diagnsotic radiology

A

False. High energy xrays are common for Therapeutic radiology.
* Low energy Xrays are common for diagnositc radiology ((dentists use diagnstic radiology to make radiographs))

83
Q

How is the statemnt ::

‘intensity (amt/qty) of radiation is inversely proportional to the square of distance bt the source and pt of measure’

used in application in clinic, diagnstic radiation?

A

Basically, the further the xray source is from the target, the less the intesity of the xray reaches the target..

IF the task is the same (to take bitewings) a greater distnace bt the rdation source and the patient would requere more radiation to travel the distanve and be strong enough to rpiduce the image, vs, reducing the distnace bt the xray source and the pt and thereby reduce the amt of radiation needed to produce the bitewings..

in clinic, by positioning hte xray tube really close to the pt, a sharper radiograph is produced using a smaller amoun of radiation (vs positioning hte pt far away from the xray tube.. to get the same radiograph would requeire a lot more radiation)

84
Q

What are the 3 mains mechanisms of Xray absorption by matter?

A

There are 3 main ways that Xrays interact with matter– via phtoelectric absorption, compton scattering, and coherent scattering.

9% of the primary photons never collide with the target matter

85
Q

what type of Xray interaction is cuased by low energy photons and is considered harmful?

A

Coherent scattering is caused by low energy photons and is considred harmful . The photon passes near an outer ring atomic electron and is deflected scattered by electron is of same energy. This coherent scattered photon is absrobed by surrounding tissue.

the aluminum flters found in xray devices serves to reduce the amount of coherent scattering that is passed to the pt.

**less than 10keV = low energy phton

86
Q

what type of Xrya -matter interaction causes secondary and teritary (chain) ioniztions?

A

Both the desireable photocelectric absorption nd the undesireable compton absorption cause secondary and teritary ionization

87
Q

which type of xray-matter interaction accounts for clinically useful radiographs?

A

Photoelectric abosroption has the effects desireable for clinical diagnosis radiographs. Photoeletric absorption exhbiits differntial absorption by differnt materials (due to thickness, density, etc) that make radiographic images

88
Q

In photoelectric absorption, the greater the atomic number of the tissue = results in more/less/the same absorption of xrya phtons

A

In photoelectric absorption, the greater the atomic number of the tissue target, the MORE the abosrption of xrays photons (therefore more radiopauw on film, or positive image on digitial)

89
Q

T/F compton absorption is a major source of scatter raidation

A

True. Compton absorption is a major source of scatter radiation – this is undesireable is diagnsosis radiology, but unavoidable.

oral radiology D2 (1 decks)

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