RADIATION PROTECTION IN RADIATION PROTECTION IN RADIOTHERAPYRADIOTHERAPY

Part 2: Radiation PhysicsPart 2: Radiation Physics

PRACTICAL EXERCISEPRACTICAL EXERCISE

IAEA Training Material on Radiation Protection in Radiotherapy

Part 2, Practical 1 2Radiotherapy

ObjectivesObjectives

To be familiar with different types of ionizing To be familiar with different types of ionizing radiationradiation

To understand the most important interaction To understand the most important interaction processes between radiation and matterprocesses between radiation and matter

To be able to use and understand all basic To be able to use and understand all basic radiation quantitiesradiation quantities

To have a basic understanding of the means To have a basic understanding of the means of radiation detectionof radiation detection

Part 2: Part 2: Radiation PhysicsRadiation Physics

Practical 1: Inverse square lawPractical 1: Inverse square law

IAEA Training Material on Radiation Protection in Radiotherapy

Part 2, Practical 1 4Radiotherapy

Contents + ObjectiveContents + Objective

Learn about the importance of distance Learn about the importance of distance as a means to reduce radiation as a means to reduce radiation exposureexposure

Perform an experiment to demonstrate Perform an experiment to demonstrate thisthis

Part 2, Practical 1 5Radiotherapy

What Minimum Equipment is What Minimum Equipment is Needed?Needed? Radiation sourceRadiation source Radiation detectorRadiation detector Tape distance measureTape distance measure Graph paperGraph paper

Part 2, Practical 1 6Radiotherapy

Radiation sourceRadiation source Ideal a 60-Co source Ideal a 60-Co source

for teaching (activity for teaching (activity <100kBq)<100kBq)

Should be high Should be high energy gamma to energy gamma to minimize attenuationminimize attenuation

Some experiments Some experiments can also be can also be performed with performed with brachytherapy sourcebrachytherapy source

Part 2, Practical 1 7Radiotherapy

Radiation detectorRadiation detector

Best a Geiger Best a Geiger counter with window counter with window thick enough to be thick enough to be mostly sensitive to mostly sensitive to gamma radiationgamma radiation

A survey meter may A survey meter may also be suitablealso be suitable

Part 2, Practical 1 8Radiotherapy

Record readings at different Record readings at different distancesdistances

distance

sourcedetector

Part 2, Practical 1 9Radiotherapy

Record and Record and plot dataplot data

Inverse Square Law Calculation SheetDate:Instrument:Source:Activity:Calibration date:

Distance(m) Reading

Instrument Relative to 1m0.10.20.5

11.5

23

0

20

40

60

80

100

0 0.5 1 1.5 2 2.5

distance from source (m)

rela

tive

det

ecto

r re

adin

g

Part 2, Practical 1 10Radiotherapy

Important consequencesImportant consequences

Distance is a powerful way to reduce Distance is a powerful way to reduce exposureexposure

Practical implications in radiotherapy:Practical implications in radiotherapy: use long tweezers to handle sources in use long tweezers to handle sources in

brachytherapybrachytherapy a long maze can reduce shielding a long maze can reduce shielding

requirements for doors significantlyrequirements for doors significantly

Part 2, Practical 1 11Radiotherapy

AcknowledgementAcknowledgement

Photos from Leybold-Didaktik web page: Photos from Leybold-Didaktik web page: www.leybold.dewww.leybold.de

Part 2, Practical 1 12Radiotherapy

Questions?Questions?

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