RADIATION DETECTION RADIATION DETECTION MONITORING DEVICES AND THEIR USEMONITORING DEVICES AND THEIR USE

Module V

Module Medical V - 2

Instruments for Instruments for ddetecting etecting and and mmeasuring easuring rradiationadiation

Survey meters Geiger-Mueller (GM) instruments Ionization chamber instruments Scintilation instruments

Laboratory counters Personnel dosimeters

Photographic film dosimeters Thermoluminescent dosimeters Pocket dosimeters

Module Medical V - 3

Primary Primary uuse of se of rradiation adiation iinstrumentnstrument

Level of radioactive contamination

Radiation dose rate in area

Identity and quantity of radioactive material

Accumulated dose to individuals in area

Survey meters

Laboratory counters

Personnel dosimeters

Module Medical V - 4

Gas filled detectorGas filled detectorss

Module Medical V - 5

Geiger-Mueller (GM) Geiger-Mueller (GM) iinstrumentsnstruments

Close-up view of probe Top: shield openBottom: shield closed

Module Medical V - 6

Determination of Determination of contamination levelcontamination level

G-M survey meter with pancake probe

Module Medical V - 7

Reading scale of GM Reading scale of GM detectordetector

Module Medical V - 8

How should you monitor?How should you monitor?

Module Medical V - 9

Surveying Surveying ppatient atient uusing sing GM GM ccounterounter

Module Medical V - 10

Limitations of Limitations of GM GM ccountersounters

will not detect very low energy betas such as those from tritium

may miss alpha contamination if any type of shielding is present, such as gauze, thin layer of blood or more than 5 cm of air

Module Medical V - 11

Alpha monitoringAlpha monitoring

alpha monitor

Module Medical V - 12

Measurement of Measurement of rradioactivityadioactivity::wwell ell ccounterounter

Module Medical V - 13

Radionuclide Radionuclide ddose ose ccalibratoralibrator

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Airborne Airborne aactivity ctivity ssamplersamplers

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Ionization Ionization cchamber hamber ssurvey urvey mmeterseters

Module Medical V - 16

Scintilation Scintilation ddetectorsetectors

Module Medical V - 17

Scintilation Scintilation survey survey mmeterseters

Module Medical V - 18

Determination of type Determination of type and and aactivity ctivity of radioactive of radioactive

materialmaterial

Module Medical V - 19

Crystal Crystal sscintillation cintillation ggamma amma sspectroscopypectroscopy

Module Medical V - 20

Liquid Liquid sscintillation cintillation ccountingounting

Module Medical V - 21

In-vivo measurementsIn-vivo measurementswhole body counters whole body counters

Module Medical V - 22

Thyroid uptake detection

Module Medical V - 23

Personnel Personnel ddosimetersosimeters

TLD

Filmbadge

Electronic dosimeter

Module Medical V - 24

Photographic Photographic ffilm ilm ddosimetersosimeters

AdvantagesPermanent

recordEnergy and

nature of exposure

Cost

DisadvantagesEnergy

dependenceFadingSize

Module Medical V - 25

Thermoluminescent Thermoluminescent ddosimetersosimeters

Module Medical V - 26

Pocket Pocket ddosimetersosimeters

Module Medical V - 27

Digital Digital ppocket ocket ddosimeterosimeter

Module Medical V

Review pointsReview points• Determination of contamination level often most important measurement in medical emergency setting Usually done with GM probe called pancake detector•Identification of radioactive material typically done by relatively sophisticated lab equipment (gamma- or alpha-spectrometer) Samples collected from patient or clothing often used for analysis • Instruments to measure accumulated dose commonly referred to as dosimeters, worn by person to measure accumulated individual dose. Two types normally used: direct read-out devices (pocket dosimeters) and indirect TLDs & film badges