Biological Effect and Radiation Protection

8/2/2019 Biological Effect and Radiation Protection

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Biological Effect andBiological Effect and

Radiation ProtectionRadiation ProtectionBy. E.QirreishBy. E.Qirreish


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Sources of RadiationSources of Radiation

Occupational Exposure:Occupational Exposure:

(Medical, radioactive waste and irradiated food).(Medical, radioactive waste and irradiated food).

Natural sources:Natural sources: (cosmic rays from sun and radiation from earth(cosmic rays from sun and radiation from earth

like uranium or radium)like uranium or radium)


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Radiation can be divided to:Radiation can be divided to:

IonizingRadiation.IonizingRadiation.

NonNon--IonizingRadiation.IonizingRadiation.

(microwaves,cell(microwaves,cell--phones, irradited food,phones, irradited food,others)others)


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Ionization RadiationIonization Radiation

When the XWhen the X--rays strike with the tissue ionizationrays strike with the tissue ionization

reactions occur bycompton process.reactions occur bycompton process.

Theories of radiation injury:Theories of radiation injury:

DirecttheoryDirecttheory: (direct damage ofcells mainly: (direct damage ofcells mainly

occurs with DNA, or RNA ofthe cells)occurs with DNA, or RNA ofthe cells) Indirecttheory.Indirecttheory.


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Indirect TheoryIndirect Theory

Photons react with the water molecules ofthe cellsPhotons react with the water molecules ofthe cells

which form hydrogen peroxide which can damagewhich form hydrogen peroxide which can damage

the cells.the cells.

XX--rays + Hrays + H22OO HH22OO++ +e+e--

HH22O + eO + e-- HH22OO

--

HH22OO-- H + OHH + OH--

These called free radicals which is unstable and canThese called free radicals which is unstable and cancombine with other free radicals and form Hcombine with other free radicals and form H22 andand

HH22OO22which is responsible for cell damage.which is responsible for cell damage.


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Risk of different Radiograph Tech.Risk of different Radiograph Tech.

The estimated riskper million of developingThe estimated riskper million of developing

cancer from dental radiograph are:cancer from dental radiograph are:

IntraIntra--oral radiograph .2 out of millions.oral radiograph .2 out of millions. OPT 1 out of 2 millions.OPT 1 out of 2 millions.

Any other skull radiograph 1.7 out of million.Any other skull radiograph 1.7 out of million.

CT Head 1 out of 10 000CT Head 1 out of 10 000


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TerminologyTerminology

Maximum Permissible Dose (MPD) also calledMaximum Permissible Dose (MPD) also calleddose equivalent: the radiation dose which isdose equivalent: the radiation dose which isallowed per annum,and this value should not beallowed per annum,and this value should not be

exceeded in order to prevent harmful effect.exceeded in order to prevent harmful effect.Measured by sievert.Measured by sievert.

Effective Dose: measure the doses fromEffective Dose: measure the doses from

different investigations of differentparts ofthedifferent investigations of differentparts ofthebodyas each part ofthe bodyaffectedbodyas each part ofthe bodyaffecteddifferently.differently.


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NationalRadiologicalProtection Board (NRPB)NationalRadiologicalProtection Board (NRPB)

estimated the effective dose of dental radiographestimated the effective dose of dental radiograph

as the follow:as the follow:

ExaminationExamination effective dose (mSv)effective dose (mSv)

I/OI/O 0.0160.016

OPGOPG 0.0070.007 CT headCT head 2.02.0


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Biological EffectsBiological Effects

Can be divided into:Can be divided into:

SomaticNonSomaticNon--Stochastic effect.Stochastic effect.

(effects on somaticcells depend definitely on the dose of exposure(effects on somaticcells depend definitely on the dose of exposureabove the threshold dose)above the threshold dose)

Somatic Stochastic effect.Somatic Stochastic effect.

(effects on somaticcells can affectunder any dose no threshold dose)(effects on somaticcells can affectunder any dose no threshold dose)

Genetic Stochastic effect.Genetic Stochastic effect.

(mutation in geneticcells can occur under any dose of exposure, no(mutation in geneticcells can occur under any dose of exposure, nothreshold dose)threshold dose)

Somatic effectcan be divided to acute or chronic effects.Somatic effectcan be divided to acute or chronic effects.


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Acute effect after radiationAcute effect after radiation

DoseDose EffectEffect

0.25 Sv0.25 Sv No effectNo effect

0.250.25--1 Sv1 Sv Blood changes (decreaseWBCs)Blood changes (decreaseWBCs)

11--2 Sv2 Sv Vomiting, fatigue blood changesVomiting, fatigue blood changes

22--6 Sv6 Sv vomiting., blood changes,loss of hairvomiting., blood changes,loss of hair

66--10 Sv10 Sv Vomiting, blood changes, death withVomiting, blood changes, death withwithin 2 weeks.within 2 weeks.

>10 Sv>10 Sv Brain damage,coma, deathBrain damage,coma, death


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Types of body cellsTypes of body cells

Permanentcells: which does not divided afterPermanentcells: which does not divided after

birth like neurons, muscle cells.birth like neurons, muscle cells.

Stabile cells: which has limited abilityto divideStabile cells: which has limited abilityto divide

after birth.after birth.

Labile cells: have high turnover rate, divided inLabile cells: have high turnover rate, divided in

constant rate, it is mostlyaffected.constant rate, it is mostlyaffected.


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Tissue types in order of sensitivityto radiation:Tissue types in order of sensitivityto radiation:

Bone marrow,thymus,thyroid.Bone marrow,thymus,thyroid.

Lymph node.Lymph node.

Hair folliclar cells, sweat gland.Hair folliclar cells, sweat gland.

Lungtissue.Lungtissue.

Bone.Bone.

Muscle.Muscle.

NeurologicaltissueNeurologicaltissue


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General effects of radiation.General effects of radiation.

Metabolicchanges: damage ofDNAMetabolicchanges: damage ofDNA mutationmutationin cellular enzyme and function.in cellular enzyme and function.

Decrease mitoticability.Decrease mitoticability. Blood vesselchanges: damage of endothelialBlood vesselchanges: damage of endothelial

lining ofthe vesselslining ofthe vessels narrowingnarrowing endarteritisendarteritisobliterants.obliterants.

Malignancy such as leukemia,lymphomaandMalignancy such as leukemia,lymphomaand

thyroid carcinoma.thyroid carcinoma.


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Effects on different tissueEffects on different tissue

Bone marrow: pancytopenia(dec. ofallcellBone marrow: pancytopenia(dec. ofallcell

types),leukemia.types),leukemia.

Thyroid gland: hypofunction,carcinoma.Thyroid gland: hypofunction,carcinoma. Reproductive cells: can lead to sterility.Reproductive cells: can lead to sterility.

Skin: radiation dermatitis (redness,ulceration ofSkin: radiation dermatitis (redness,ulceration of

skin),carcinoma or melanoma.skin),carcinoma or melanoma. Hair: alopecia.Hair: alopecia.


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Mucosa: radiation mucositis (erythemia,Mucosa: radiation mucositis (erythemia,

ulceration), malulceration), mal--absorption and diarrhea.absorption and diarrhea.

Glands: depend on dose, hypofunction,atrophy.Glands: depend on dose, hypofunction,atrophy.On salivary gland itcan lead to XerostomiaOn salivary gland itcan lead to Xerostomia

which cause radiation caries,perio diseases.which cause radiation caries,perio diseases.

Bone: endarteritis obliterans causes stunting ofBone: endarteritis obliterans causes stunting of

the growth, osteoradionecrosis, secondarythe growth, osteoradionecrosis, secondary

malignancy.malignancy.


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Teeth: low radiationTeeth: low radiation delay eruption in children,delay eruption in children,

higher dosehigher dose damage of developingcells pdamage of developingcells phypoplasia of enameland dentine, very high doehypoplasia of enameland dentine, very high doe

aplasialoss ofteeth. And can cause caries inaplasialoss ofteeth. And can cause caries inelder age.elder age.


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Radiation ProtectionRadiation Protection

Ionization radiations regulations.Ionization radiations regulations.

1985.1985. 1987.1987.


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Ionization Radiation Regulation 1985Ionization Radiation Regulation 1985

Practitioners must inform the HSE abouttypePractitioners must inform the HSE abouttype

and serial number ofthe machines.and serial number ofthe machines.

Patient must be the only one in controlled areaPatient must be the only one in controlled area(C.A),and the size ofC.A depend on voltage(C.A),and the size ofC.A depend on voltage

ofthe unit.ofthe unit.

Practitioner mustprovide adequatePractitioner mustprovide adequate

information aboutthe radiation to the stuffinformation aboutthe radiation to the stuff

members.members.


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RPS must be appointed.RPS must be appointed.

RPA must be appointed in the followingcases:RPA must be appointed in the followingcases:

1.1. Patient notalone in the C.APatient notalone in the C.A

2.2. More than 300 I.O films a week(D speed films)More than 300 I.O films a week(D speed films)

3.3. More than 50 Pans a week.More than 50 Pans a week.

4.4. 2 units in one room.2 units in one room.

5.5. Cephalostat is used.Cephalostat is used.


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Local rules.Local rules.

Machine should be subjected to specificMachine should be subjected to specific

legalization rules:legalization rules:1.1. kV notless than 50 and preferable 70.kV notless than 50 and preferable 70.

2.2. Beam diameter not more than 60 mm.Beam diameter not more than 60 mm.

3.3. Less than 70kV 1.5 aluminum sheet forLess than 70kV 1.5 aluminum sheet forfiltration and 2.5 of sheet ifthe voltage morefiltration and 2.5 of sheet ifthe voltage more

than 70 kV.than 70 kV.


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Equipment must be maintained and recordsEquipment must be maintained and records

should be kept for the type,age and checkupshould be kept for the type,age and checkup

visits.visits.

The fastest film available should be used.The fastest film available should be used.


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Ionization RadiationIonization Radiation

Regulations1988Regulations1988

Adequate training ofthe stuff members.Adequate training ofthe stuff members.

Dentist nottrained before the 1988 regulationDentist nottrained before the 1988 regulation

must be tutored.must be tutored. Personnelare divided into:Personnelare divided into:

1.1. Clinical directors.Clinical directors.

2.2. Physical director.Physical director.


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Current GuidelinesCurrent Guidelines

NRPB published guidelines (1994) includeNRPB published guidelines (1994) includeinformation about:information about:

Training needed.Training needed.

Patient selection.Patient selection.

Interpretation.Interpretation.

Technique.Technique.

Equipment.Equipment.

QualityAssurance.QualityAssurance.


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Radiation Dose LimitationsRadiation Dose Limitations

GeneralPrinciples byICRP:GeneralPrinciples byICRP:

1.1. No radiograph should be done withoutpositiveNo radiograph should be done withoutpositive

net benefit.net benefit.

2.2. All exposure should be keptALARA.All exposure should be keptALARA.

3.3. The equivalent dose should not exceed theThe equivalent dose should not exceed the

recommended dose.recommended dose.


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ALARAConceptALARAConcept

Stands forStands for as low as reasonable achievable.as low as reasonable achievable.

No conceptcould be anyclearer. Keep exposureNo conceptcould be anyclearer. Keep exposure

as lowas reasonablyachievable. This principle isas lowas reasonablyachievable. This principle is

based on the premise thatall radiation exposurebased on the premise thatall radiation exposure

entails some degree of risk. All radiation isentails some degree of risk. All radiation is

potentially harmful. Like acne when youare apotentially harmful. Like acne when youare a

teenagerthe less the better.teenagerthe less the better.


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Specificpoints:Specificpoints:

1.1.Maximalallowable dose for radiation worker perMaximalallowable dose for radiation worker per

year should not exceed 20 mSv.year should not exceed 20 mSv.2.2.Not more than 100mSvper 5 years andNot more than 100mSvper 5 years and

maximum 50mSv in one year ofthem.maximum 50mSv in one year ofthem.

3.3.No limitations for the patients.No limitations for the patients.4.4.The maximum dose ofpublicare divided by 10The maximum dose ofpublicare divided by 10

ofthe radiation worker.ofthe radiation worker.


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ICRP has divided population to 3 groups:ICRP has divided population to 3 groups:

PatientPatient WorkerWorker

publicpublic


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Patient:Patient:

1.1. Diseased one.Diseased one.

2.2. Checkup.Checkup.3.3. Insurance.Insurance.

4.4. Medical research.Medical research.

Worker:Worker:

1.1. ClassifiedClassified

2.2. NonNon--classified.classified.


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Radiation Protection MeasuresRadiation Protection Measures

Public:Public:

1.1. Include persons live or work in the areasInclude persons live or work in the areas

where near to radiation.where near to radiation.2.2. The offices must be protected bylead shield orThe offices must be protected bylead shield or

concrete wall.concrete wall.


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Patient:Patient:

1.1. No limit for taking radiographs.No limit for taking radiographs.

2.2. Patient must notconcerned about 18 radiographs asPatient must notconcerned about 18 radiographs aseach one is taken at differentpart.each one is taken at differentpart.

3.3. Radiation worker is considered as patient when he is inRadiation worker is considered as patient when he is in--need for radiograph.need for radiograph.

4.4. Lead apron must be used??Lead apron must be used??5.5. Thyroid apron??Thyroid apron??6.6. Room size should be minimum 2.5 x 2.5m.Room size should be minimum 2.5 x 2.5m.7.7. Exposure should be decrease as possible.Exposure should be decrease as possible.

8.8. Use cone, diaphragm.Use cone, diaphragm.9.9. High speed film, or digital.High speed film, or digital.10.10.XX--raytube should be tested always.raytube should be tested always.11.11.Use dead mantype of switch during exposure.Use dead mantype of switch during exposure.


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Radiation worker:Radiation worker:

1.1. Leaded walland glasses.Leaded walland glasses.

2.2. Safe position by being behind the patient 2m attheSafe position by being behind the patient 2m attheback in 45 degree angle.back in 45 degree angle.

3.3. Use less exposure with collimator.Use less exposure with collimator.4.4. Try 2 produce good radiograph, not 2 repeat.Try 2 produce good radiograph, not 2 repeat.

5.5. The room height is 2.15m.The room height is 2.15m.6.6. Operator must stand behind the leaded screen if noOperator must stand behind the leaded screen if no

wall separating worker from the Xwall separating worker from the X--raytube.raytube.7.7. Notallowed to be less than 18 years who is takingtheNotallowed to be less than 18 years who is takingthe

radiogr

aph.r

adiogr

aph.8.8. Door is leaded,and closed duringthe process.Door is leaded,and closed duringthe process.

9.9. Directthe tube in aposition notaimed to the door orDirectthe tube in aposition notaimed to the door orglasses.glasses.

10.10. Measuring radiation device must be used.Measuring radiation device must be used.


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Measure rad. devicesMeasure rad. devices

Types:Types:

1.1. Film badge.Film badge.2.2. Thermoluminescent dosimeters (TLD).Thermoluminescent dosimeters (TLD).

3.3. Ionization chamber.Ionization chamber.


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The EndThe End

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Biological Effect and Radiation Protection