Dose Course 2018_Flipping book

Detector

Appropiate for

Be careful

❑ For x-ray depth dose measurements

Check polarity effect for both photon and electron beams Always measure with the same nominal V For micro-chambers the stem signal can be an issue Correct by Sw,air for electron depth dose measurements. Use small volume detectors for scanning

Ionization chambers

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Plane-parallel chamber for build-up region

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❑ Output factors large fields

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❑ Output factors for small fields (micro-chambers)

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Effective point of measurement

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Check stability temperature during measurements

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❑ Depth dose measurements and profiles

Energy dependence

Diodes

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Sensitivity variation with accumulated dose

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Shielded detector for x-rays

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Non-shielded for electron beams

❑ May present sensitivity variation with dose rate

Output factors

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Check stability temperature during measurements

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Shielded detector standard/large fields

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Non-shielded for small fields