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Part IIPart II Quantities and MeasurementsQuantities and Measurements

Module 3Module 3 Principles of Radiation Principles of Radiation Detection and MeasurementDetection and Measurement

Session 6Session 6 Photographic EmulsionsPhotographic Emulsions

Session II.3.6Session II.3.6

IAEA Post Graduate Educational CourseIAEA Post Graduate Educational CourseRadiation Protection and Safe Use of Radiation SourcesRadiation Protection and Safe Use of Radiation Sources

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OverviewOverview

In this Session we will discuss photographic In this Session we will discuss photographic emulsions and their use as radiation emulsions and their use as radiation dosimeters.dosimeters.

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A film badge is a A film badge is a passive dosimeterpassive dosimeter

It can measure deep, It can measure deep, eye and skin dose eye and skin dose depending on the depending on the filtration usedfiltration used

It can also indicate the It can also indicate the energy of the radiation energy of the radiation to which it was exposedto which it was exposed

Film BadgeFilm Badge

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Common PassiveCommon PassivePersonal DosimetersPersonal Dosimeters

Film BadgeFilm Badge Cheap Cheap Permanent recordPermanent record Energy correction requiredEnergy correction required

Thermoluminescent Dosimeter (TLD)Thermoluminescent Dosimeter (TLD) Re-useableRe-useable Easily automatedEasily automated More sensitive than film More sensitive than film

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Typical ProcessedTypical ProcessedDosimetry FilmDosimetry Film

Film holder has many Film holder has many different absorbers different absorbers (filters)(filters)

Differential reading and Differential reading and appropriate calibration appropriate calibration allows assessment of allows assessment of radiation quality (type radiation quality (type and energy) and doseand energy) and dose

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Film dosimeters (commonly known as film badges) Film dosimeters (commonly known as film badges) consist of a piece of photographic film in a holderconsist of a piece of photographic film in a holder

The holder is fitted with a range of filters which The holder is fitted with a range of filters which allows us to distinguish between beta, x-ray, gamma allows us to distinguish between beta, x-ray, gamma and thermal neutron radiations and also allows and thermal neutron radiations and also allows determination of the personal dose equivalent for determination of the personal dose equivalent for HHpp(10), H(10), H

pp(0.07) and H(0.07) and Hpp(3)(3)

Film DosimeterFilm Dosimeter

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By determining the degree of blackening (optical By determining the degree of blackening (optical density) on the developed film and comparing it with density) on the developed film and comparing it with calibrated films that have been exposed to known calibrated films that have been exposed to known doses, it is possible to ascertain both the total dose doses, it is possible to ascertain both the total dose received by the wearer and also the contribution to received by the wearer and also the contribution to total dose by each type of radiationtotal dose by each type of radiation

The various filters used in film badges to ascertain The various filters used in film badges to ascertain whole body Hwhole body H

pp(10), skin H(10), skin Hpp(0.07) and eye H(0.07) and eye H

pp(3) doses (3) doses

are shown in the following Figure and Tableare shown in the following Figure and Table

Film DosimeterFilm Dosimeter

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Film DosimeterFilm Dosimeter

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Filter MaterialFilter Material ApplicationApplicationOpen WindowOpen Window beta and very soft x-raysbeta and very soft x-raysPlastic (50 mg cmPlastic (50 mg cm-2-2)) and x-ray dose and energy* and x-ray dose and energy*Plastic (300 mg cmPlastic (300 mg cm-2-2)) and x-ray dose and energy* and x-ray dose and energy*Dural (0.040”)Dural (0.040”) and x-ray dose and energy* and x-ray dose and energy*Sn + Pb (0.028” 0.012”)Sn + Pb (0.028” 0.012”) and x-ray dose and energy* and x-ray dose and energy*Cd + Pb (0.028” 0.012”)Cd + Pb (0.028” 0.012”) slow neutrons**slow neutrons**Lead (0.012”)Lead (0.012”) edge shieldingedge shielding++

Indium (0.4 g)Indium (0.4 g) neutron accident monitoringneutron accident monitoring

**quantitative determination ofquantitative determination of** ** by gamma emitted after capture by cadmiumby gamma emitted after capture by cadmium++to prevent overlap of film blackening due to angled incident radiationto prevent overlap of film blackening due to angled incident radiation

Film DosimeterFilm Dosimeter

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Film badges are particularly useful for measuring Film badges are particularly useful for measuring doses to individuals as information on both the type doses to individuals as information on both the type and energy of the radiation received can often be and energy of the radiation received can often be determineddetermined

Also, the presence of surface contamination on the Also, the presence of surface contamination on the holder can be ascertained by an irregular darkening holder can be ascertained by an irregular darkening of the filmof the film

Another advantage of this type of dosimeter is that Another advantage of this type of dosimeter is that the films can be kept as a permanent record of an the films can be kept as a permanent record of an individual’s doseindividual’s dose

Film DosimeterFilm Dosimeter

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This means that they can be reassessed at a later This means that they can be reassessed at a later date if necessarydate if necessary

Undesirable features of the film badge are their Undesirable features of the film badge are their adverse effects to light and heatadverse effects to light and heat

They also require dark room facilities (with They also require dark room facilities (with associated development chemicals) and significant associated development chemicals) and significant manual handling during assessmentmanual handling during assessment

Another major disadvantage is that the films cannot Another major disadvantage is that the films cannot be reused and, although they are cheap, they are in be reused and, although they are cheap, they are in limited supplylimited supply

Film DosimeterFilm Dosimeter

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Film DosimeterFilm Dosimeter

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Film PropertiesFilm Properties

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Film PropertiesFilm Properties

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The density on the film results from three The density on the film results from three basic sources:basic sources:

BaseBase

FogFog

ExposureExposure

Film PropertiesFilm Properties

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DOSIMETER FILMDOSIMETER FILM

Black = exposedBlack = exposedWhite = not exposedWhite = not exposed

How was this film How was this film badge exposed?badge exposed?

Pb Filter

Exposed Personnel DosimeterExposed Personnel Dosimeter

Al Filter

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openopenwindowwindow

Shallow to deep ratio =Shallow to deep ratio =HHpp(10)(10)

HHpp(0.07)(0.07)

0°0°

4545

90°90°

Orientation EffectsOrientation Effects

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Where to Get More InformationWhere to Get More Information

Cember, H., Introduction to Health Physics, 3Cember, H., Introduction to Health Physics, 3rdrd Edition, McGraw-Hill, New York (2000)Edition, McGraw-Hill, New York (2000)

Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Table of Isotopes (8Table of Isotopes (8thth Edition, 1999 update), Wiley, Edition, 1999 update), Wiley, New York (1999)New York (1999)

International Atomic Energy Agency, The Safe Use International Atomic Energy Agency, The Safe Use of Radiation Sources, Training Course Series No. 6, of Radiation Sources, Training Course Series No. 6, IAEA, Vienna (1995)IAEA, Vienna (1995)