+ All Categories
Home > Documents > RAD 100 - Ch.9, Rad. Prot.

RAD 100 - Ch.9, Rad. Prot.

Date post: 09-Apr-2018
Category:
Upload: rwjj1975
View: 237 times
Download: 0 times
Share this document with a friend

of 23

Transcript
  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    1/23

    RAD 100RAD 100 -- IntroductionIntroduction

    to Clinical Radiographyto Clinical Radiography

    Chapter 9: Basic RadiationChapter 9: Basic Radiation

    ProtectionProtection

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    2/23

    Basic Radiation ProtectionBasic Radiation Protection

    Ionizing Radiation is used to produce aIonizing Radiation is used to produce a

    diagnostic image for the radiologistdiagnostic image for the radiologist

    Benefits must outweigh the riskBenefits must outweigh the risk

    Sources of radiation include:Sources of radiation include:

    Natural or background:Natural or background: energy from sun & otherenergy from sun & other

    planets and naturally occurring radioactive substancesplanets and naturally occurring radioactive substances

    present on the earth such as uranium and radonpresent on the earth such as uranium and radon ManMan--made:made: nuclear energy, radionuclides, and medicalnuclear energy, radionuclides, and medical

    & dental x& dental x--raysrays

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    3/23

    XX--rays travel at speed of lightrays travel at speed of light

    3 things must be present for x3 things must be present for x--rayray

    productionproduction

    A source of electronsA source of electrons

    A force to rapidly move themA force to rapidly move them

    Something to stop the movement rapidly!Something to stop the movement rapidly!

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    4/23

    These 3 items are met by theThese 3 items are met by the

    xx--ray tube & the electricityray tube & the electricity

    supplied to the tube.supplied to the tube. The tube is composed of:The tube is composed of:

    AnodeAnode positive terminalpositive terminal

    CathodeCathode negative terminalnegative terminal

    FilamentFilament made of thoriated tungsten (Thismade of thoriated tungsten (This

    provides the source of electrons)provides the source of electrons)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    5/23

    XX--ray production occurs when:ray production occurs when:

    Kilovoltage is applied to filamentKilovoltage is applied to filament

    The stream of electrons is rapidly acceleratedThe stream of electrons is rapidly accelerated

    to the anodeto the anode Upon striking the anode, they undergo energyUpon striking the anode, they undergo energy

    conversionconversion This produces both heat and energyThis produces both heat and energy

    The beam that results is heterogenous andThe beam that results is heterogenous andmeasure in kiloelectron volts (keV)measure in kiloelectron volts (keV)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    6/23

    XX--rays are produced!rays are produced!

    These xThese x--rays are known as the primary beamrays are known as the primary beam

    and exit the tube through a glass window in theand exit the tube through a glass window in the

    tube.tube.

    Once they strike the patient 3 possibilities exist:Once they strike the patient 3 possibilities exist:

    They can be absorbedThey can be absorbed

    They can transfer some energy & then scatterThey can transfer some energy & then scatter

    They can pass through the patient unaffectedThey can pass through the patient unaffected

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    7/23

    XX--rays interact withrays interact with

    matter in five ways:matter in five ways: 3 of these occur within the diagnostic3 of these occur within the diagnostic

    range of xrange of x--ray energiesray energies

    Classic coherent scatteringClassic coherent scattering Photoelectric interactionsPhotoelectric interactions

    This type of interaction results in the greatestThis type of interaction results in the greatesthazard to patientshazard to patients

    Compton scatteringCompton scattering This type of interaction results in the greatestThis type of interaction results in the greatest

    amount of exposure to us as radiographers!amount of exposure to us as radiographers!

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    8/23

    XX--rays interact withrays interact with

    matter in five ways:matter in five ways: 2 more interactions occur in energies that2 more interactions occur in energies that

    are higher than levels which occurr inare higher than levels which occurr in

    diagnostic xdiagnostic x--rayray

    Pair productionPair production

    PhotodisintregationPhotodisintregation

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    9/23

    Ionizing radiation can be quantifiedIonizing radiation can be quantified

    Units of measurement:Units of measurement: Units most commonly used since 1920s in Table 9Units most commonly used since 1920s in Table 9--11

    SI (International System of Units) was adopted in 1985SI (International System of Units) was adopted in 1985 (Roentgen/R) or Coulomb/kilogram(Roentgen/R) or Coulomb/kilogram measure of exposuremeasure of exposure

    in airin air

    (Rad) or Gray/G(Rad) or Gray/G measures absorbed dose in any mediummeasures absorbed dose in any medium

    (Rem) or Sievert/Sv(Rem) or Sievert/Sv radiation equivalent to manradiation equivalent to man

    (The unit of absorbed dose in man regardless of type of(The unit of absorbed dose in man regardless of type ofradiation that is used.)radiation that is used.)

    (Curie) or Becquerel(Curie) or Becquerel measures activity (how fast ameasures activity (how fast a

    radionuclide decays)radionuclide decays)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    10/23

    Standards for RegulationStandards for Regulation

    of Exposureof Exposure Limits must be set to ensure safety forLimits must be set to ensure safety for

    both patient and the radiation workersboth patient and the radiation workers

    National Council on Radiation ProtectionNational Council on Radiation Protection(NCRP)(NCRP)

    Advisory group that helps to establish radiationAdvisory group that helps to establish radiation

    protection standardsprotection standards

    Current practice is to apply ALARA concept:Current practice is to apply ALARA concept:

    As Low As Reasonably AchievableAs Low As Reasonably Achievable

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    11/23

    Effective dose limit recommendations:Effective dose limit recommendations:

    Annual whole body dose for theAnnual whole body dose for the

    occupational worker is:occupational worker is:

    50 mSv (5 rem)50 mSv (5 rem)

    Annual whole body dose for the generalAnnual whole body dose for the general

    population is 1/10 the exposure forpopulation is 1/10 the exposure forworkers, or:workers, or:

    5 mSv (.5 rem)5 mSv (.5 rem)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    12/23

    Review of cellular structure and howReview of cellular structure and how

    radiation interacts with cells:radiation interacts with cells:

    A cell is the simplest unit of protoplasmA cell is the simplest unit of protoplasmthat is capable of living independently.that is capable of living independently.

    Cells are divided into:Cells are divided into: the nucleus which is made up of genesthe nucleus which is made up of genes

    the cytoplasm which is primarily made of waterthe cytoplasm which is primarily made of water

    There are 2 cell types.There are 2 cell types.

    Somatic cells which perform the bodysSomatic cells which perform the bodysfunctionsfunctions

    Germ cells which are reproductive cellsGerm cells which are reproductive cells

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    13/23

    How do cells respond to radiation?How do cells respond to radiation?

    The total body response: the radiationThe total body response: the radiation

    effects to all systems of the bodyeffects to all systems of the body

    3 general stages:3 general stages:

    Prodomal stage: NVD stageProdomal stage: NVD stage

    Latent period: the patient feels well, but the bodyLatent period: the patient feels well, but the body

    is undergoing biologic changes that will lead tois undergoing biologic changes that will lead to

    Manifest stage: Leads to either recovery or deathManifest stage: Leads to either recovery or death

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    14/23

    As a result of overexposure, there are 3As a result of overexposure, there are 3

    radiation syndromes that occurradiation syndromes that occur

    Bone marrow syndromeBone marrow syndrome

    Results in infection, hemorrhage and anemiaResults in infection, hemorrhage and anemia

    Gastrointestinal syndromeGastrointestinal syndrome

    Results in excessive diarrhea, nausea &Results in excessive diarrhea, nausea &

    vomitingvomiting

    Central nervous system syndromeCentral nervous system syndrome Results in convulsions, coma and eventuallyResults in convulsions, coma and eventually

    death due to increased intracranial pressuredeath due to increased intracranial pressure

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    15/23

    Other effects of radiation areOther effects of radiation are

    also important!also important! Late effects can develop over a longLate effects can develop over a long

    period after the exposureperiod after the exposure

    These late effects are divided into 2 groupsThese late effects are divided into 2 groups Somatic effects: develops in those peopleSomatic effects: develops in those people

    exposedexposed 2 most common somatic effects are cataracts and2 most common somatic effects are cataracts and

    cancer developmentcancer development

    Genetic effects: occur in future generations as aGenetic effects: occur in future generations as aresult of damage to germ cells when mutatedresult of damage to germ cells when mutatedcells are fertilized by another mutated cellcells are fertilized by another mutated cell

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    16/23

    How do we protect the patient?How do we protect the patient?

    Use the ALARA conceptUse the ALARA concept

    Use the 3 cardinal principles of protectionUse the 3 cardinal principles of protection

    TimeTime Use proper techniques to reduce repeatsUse proper techniques to reduce repeats

    DistanceDistance

    Not the most reasonable method for the patient, but worksNot the most reasonable method for the patient, but works

    well for you!well for you!

    ShieldingShielding

    When the primary beam is within 4When the primary beam is within 4--5 cm. of reproductive5 cm. of reproductive

    organs (See Fig. 9organs (See Fig. 9--9, pg, 120)9, pg, 120)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    17/23

    Other methods of patientOther methods of patient

    protection:protection:

    Beam restrictionBeam restriction

    Proper film/screen combinationsProper film/screen combinations

    Correct technical factor selectionCorrect technical factor selection

    Using proper filtration exiting from xUsing proper filtration exiting from x--rayray

    beambeam

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    18/23

    How do we protect ourselves?How do we protect ourselves?

    TimeTime Limit your time in exposure, especially during fluoroscopyLimit your time in exposure, especially during fluoroscopy

    DistanceDistance the best protection of all!the best protection of all! Inverse square law: doubling your distance reduces your exposure toInverse square law: doubling your distance reduces your exposure to

    of original of original Use immobilization devices or restraints when possible to reduce yourUse immobilization devices or restraints when possible to reduce your

    exposureexposure

    ShieldingShielding -- use lead aprons & glovesuse lead aprons & gloves These devices should contain between .25 & I.0 mm of leadThese devices should contain between .25 & I.0 mm of lead

    Fixed barriersFixed barriers Primary barriers: those struck by primary beamPrimary barriers: those struck by primary beam

    Secondary barriers: those struck by scatter beam (lead or concrete)Secondary barriers: those struck by scatter beam (lead or concrete)

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    19/23

    Student pregnancy is covered by theStudent pregnancy is covered by the

    Nuclear Regulatory Commision (NRC)Nuclear Regulatory Commision (NRC)

    Once pregnancy is known, a limit of .05Once pregnancy is known, a limit of .05rem (.5 mSv) per month should applyrem (.5 mSv) per month should apply

    Though average exposure to the radiologicThough average exposure to the radiologictechnologist is unlikely to exceed thesetechnologist is unlikely to exceed theselimits, there is little reason not to declare alimits, there is little reason not to declare apregnancy or alter a clinical assignment.pregnancy or alter a clinical assignment.

    Declaration is voluntary & must be made inDeclaration is voluntary & must be made inwritingwriting

    A second monitor is used at the level of the fetusA second monitor is used at the level of the fetusand must not exceed .005 rem (.05 mSv)/monthand must not exceed .005 rem (.05 mSv)/month

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    20/23

    Radiation monitoringRadiation monitoring

    determines your exposure.determines your exposure. Most 5 most common personnel devices are:Most 5 most common personnel devices are:

    OSL (optically stimulated luminescence)OSL (optically stimulated luminescence)

    dosimeter: most common methoddosimeter: most common method Worn between the collar & waist outside of a leadWorn between the collar & waist outside of a lead

    apronapron

    Advantageous because it is unaffected by heat,Advantageous because it is unaffected by heat,

    moisture and pressuremoisture and pressure Its disadvantage is that you cannot get anIts disadvantage is that you cannot get an

    immediate reading of exposureimmediate reading of exposure

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    21/23

    Radiation monitoring:Radiation monitoring:

    Film Badges: these were the mostFilm Badges: these were the most

    popular and least expensive ways topopular and least expensive ways to

    monitor exposuremonitor exposure Its main disadvantage is its inability to get anIts main disadvantage is its inability to get an

    immediate reading of exposureimmediate reading of exposure

    Thermoluminescent dosimeters: usesThermoluminescent dosimeters: useslithium fluoride crystalslithium fluoride crystals

    Advantageous because they can be reusedAdvantageous because they can be reused

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    22/23

    Radiation monitoring:Radiation monitoring:

    Pocket dosimeters: used when anPocket dosimeters: used when an

    immediate reading is desiredimmediate reading is desired

    Disadvantage: subject to false readings andDisadvantage: subject to false readings and

    does not provide a permanent recorddoes not provide a permanent record

  • 8/8/2019 RAD 100 - Ch.9, Rad. Prot.

    23/23

    Radiation monitoring:Radiation monitoring:

    Field survey instruments can also detectField survey instruments can also detect

    the presence of radiation in the airthe presence of radiation in the air

    A common type is GeigerA common type is Geiger--Muller counterMuller counter

    These units are used in nuclear medicine toThese units are used in nuclear medicine todetect the possibility of spilled radionuclidesdetect the possibility of spilled radionuclides


Recommended