Technical Guidance

Radiation shielding data for use with F-18. Provides examples of lead thickness against transmission, and compares with concrete (3 densities considered) and steel. Based on broad beam conditions. Useful for shielding sanity checks during the initial design of PET shielding facilities.

Imagine an uncollimated radioactive source (e.g. Se-75 or similar) in the middle of a concrete shielded enclosure which is open topped.  The shielding is designed to mitigate all direct radiation from the source down to background levels on the outside of the enclosure. Any remaining exposure potential is from skyshine. This latest widget explores skyshine in terms of dose rate where the horizontal and vertical measurement position can be explored, and where the vertical height of the source can be adjusted. Some of the results provided may surprise you. Developed for Ionactive by Dr Chris Robbins from Grallator.

You are performing a critical examination on an x-ray cabinet where you find a small radiation "leak" measuring slightly >1 micro Sv/h on the surface. What is the potential whole body radiation exposure from this situation? How does it vary with the position of the source (x-ray collimator) to the inner surface of the x-ray cabinet covers? And how does it vary with the diameter of the shielding deficiency or the distance of the monitoring prob to the x-ray cabinet covers? Explore these radiation protection questions with this widget.  Developed for Ionactive by Dr Chris Robbins from Grallator.

How does a radiation protection maze (labyrinth) work? What dose rate would you receive if you were to move up the maze (if you were allowed to). No dog-leg (so you need a shielding door), one dog-leg or two dog-leg? How about a drop down lintel? Collimated source or uncollimated? Area of collimation? Scatter vs direct ray path? Mazes are often present in radiotherapy treatment rooms, industrial radiography enclosures, industrial irradiation facilities and similar. This widget uses a 10 MV collimated and uncollimated ionising radiation source to explore these concepts. In addition, the widget is used to describe good, and not so good practice in radiation shielding design, with practical examples. Developed for Ionactive by Dr Chris Robbins from Grallator.

Gamma / x-ray dose rate measurements for radiation protection purposes are not always as simple as first expected. Is the emitting source true 4π geometry, 2π or collimated in some way? The same questions can be asked of the detector (most radiation monitors are 2π).  Furthermore, how do the photons scatter within the region between source and detector - do they leave the region before being detected, or are some of them scattered back towards the detector? Are the scatters truly random or could they be influenced in some way? This is the first of several radiation protection widgets, created for Ionactive by Dr Chris Robbins (Grallator), which will explore photon scattering and it's impact on radiation protection and detection. 

Imagine a geometry situation other than a simple point source of radiation from radioactive material. Further imagine the interior surface of a tungsten cone containing radioactive material from neutron activation - the distribution of activity being variable depending on the circumstances of the irradiation. What might the dose rate be,  measured by a radiation detector placed at the open end of the cone? How would this dose rate change with distance from the cone, with distribution of radioactivity within the cone, and with the shape of the cone? This is explored in our latest widget, developed for Ionactive by Dr Chris Robbins from Grallator.