Technical Guidance

Here you will find data and articles on radiation shielding, frequently asked questions (FAQ), monitor performance, specific gamma ray constants, mathematical derivations, radiation protection widgets  - everything we have personally found useful from our own tool kit. New resources will be uploaded here from time to time.

For formal radiation safety advice, visit our Radiation Protection Adviser (RPA) services page. 

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  • Skyshine – radiation scattering around and over shielding

    Published: Sept 29, 2021

    Source: Ionactive Radiation Protection Resource

      Tags:
    • Skyshine
    • Radiation Shielding
    • Open top radiography
    • Radiation scatter
    • Radiation skyshine widget

    A easy to read explanation of radiation skyshine (usually x-ray or gamma ray photons, or neutrons) which can leave an open topped (or lightly shielded) enclosure at height, and reach ground level some distance away. In some cases skyshine can yield a peak ground level dose rate which is some distance away from the shielding wall. 

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  • Radioisotope Beta Skin Contamination Dose Rates

    Published: Sept 29, 2021

    Source: Ionactive Radiation Protection Resource

      Tags:
    • Beta emitter
    • Beta Radioisotope
    • Beta skin dose
    • Beta skin dose rate
    • H-3
    • C-14
    • P-32
    • P-33
    • S-35
    • Ca-45

    Radioisotope beta skin contamination dose rates for some selected radioactive materials (C-14, S-35, P-32, P-33, Ca-45 and Cr-51 for comparison). Assumes no PPE is being worn (e.g. gloves etc). [Updated August 2025].

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  • Inverse Square Law - when is a source a point source?

    Published: Sept 29, 2021

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  • Protection by reducing exposure time - is it always valid?

    Published: Sept 29, 2021

      Tags:
    • Ionising Radiation
    • Protection by time
    • Very high dose rates
    • High activity Co
    • HASS source
    • Pure alpha emitter
    • Po-210
    • Polonium-210
    • Cabinet x-ray systems
    • < 1 μSv/h
    • < 1 micro Sv/h

    Protection by reducing exposure time to ionising radiation is a recognised practice. However, are there occasions where this is not so valid (or not valid at all )? This guidance provides some examples to illustrate this. 

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  • The 10 half-life rule of thumb for radioactive materials

    Published: Sept 29, 2021

    Source: Ionactive Radiation Protection Resources

      Tags:
    • Radioactive Decay
    • Half-Life
    • Half-Life calculations
    • 10 Half-Life Rule
    • Dose Rate
    • beta radiation
    • Gamma rays

    The 10-half-life reduction rule is an approximation but useful for evaluating contingency plans. This example explains the concept with examples and interactive decay curve plots. 

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  • Typical radiation exposure from medical diagnostic procedures

    Published: Sept 29, 2021

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Reality is merely an illusion, albeit a very persistent one

– Albert Einstein -