During our Radiation Protection Supervisor (RPS) training courses we reassure delegates that there is very little in the way of complicated maths or physics – its generally not important when working safely with ionising radiation (understanding the concepts are important). However, there is a good dose of physics and mathematics behind these concepts and principles which is what you will find in this area of the site. Mathematical derivation, shielding calculations, and other health physics concepts are featured.

• ## Radioactive source holders - Dose rate through an aperture

Published: Apr 23, 2024

Source: Dr Chris Robbins, Grallator / Ionactive radiation protection resource

Tags:
• Shielding aperture
• Nuclear gauge
• Nuclear density gauge
• Whole body exposure
• effective dose
• Nuclear gauge accident dose rates
• Inverse square law
• Multi-phase flow meter

This article, and our discussions with Dr Chris Robbins of Grallator, was born from a consideration of when a radioactive source holder (such as that fitted as part of a nuclear gauge) might become detached during a radiation accident, such that the radiation from the source is exposed directly through a small aperture. This is reasonably foreseeable compared to a radioactive source which might be completely exposed (unshielded). What would the dose rates be at a certain distance from the source holder, and what % of the trunk of the body would be exposed? This article considers the maths / physics behind this situation which has been developed for Ionactive by Chris. Ionactive has then taken the results of this analysis and shown how it would apply to a real world radiation accident.

• ## Calculate an estimate of x-ray dose rate from an x-ray tube given kV and mA

Published: Mar 24, 2024

Source: Dr Chris Robbins, Grallator/ Ionactive Radiation Protection Resource

Tags:
• X-ray
• X-ray dose rate
• X-ray generator
• mA
• kV
• Calculate x-ray tube output
• Formula for x-ray tube output
• Calculate x-ray tube dose rate
• Anode
• Cathode
• Bremsstrahlung x-rays
• Characteristic X-rays
• Tungsten target
• Inverse square law
• Energy Absorption
• Mass Energy Absorption Coefficient
• Gray (Gy)
• NDT X-ray tube
• Medical X-ray tube

How do you calculate an estimate of dose rate from an X-ray tube give kV and mA? In this resource we consider a 'ballpark' estimate of radiation dose rate using some physics principles, including an estimate of % bremsstrahlung from an anode target, combined with a calculation of power density and consideration of average energy absorption rate.

• ## When $$1/d^2$$ breaks down - part 2: area source

Published: Mar 22, 2024

Source: Dr Chris Robbins, Grallator

Tags:
• 1/d2 for an area source
• Inverse square law

When $$1/d^2$$ breaks down - part 2: area source. Using some mathematics to explore how the inverse square law works with a radiation area source.

• ## When $$1/d^2$$ breaks down - part 1: line source

Published: Mar 22, 2024

Source: Dr Chris Robbins, Grallator

Tags:
• 1/d2 for a line source
• Inverse square law

When $$1/d^2$$ breaks down - part 1: line source. Using some mathematics to explore how the inverse square law works with a radiation line source.

• ## The accumulated radiation dose when moving up to a source

Published: Nov 27, 2023

Source: Dr Chris Robbins, Grallator

Tags:
• Dr Chris Robbins
• Grallator
• Accumulated dose
• accumulated radiation exposure moving towards a source
• Inverse square law
• Point source

Consider the situation where you move up to a radioactive source, perform some operations for a period of time, and then move away. What total dose will be received?

• ## Physical, biological and effective half-life

Published: Sep 29, 2021

Source: Dr Chris Robbins, Grallator

Tags:
• Physical half-half
• Biological Half-Life
• Effective Half-Life
• Half-Life
• Health Physics
• Maths
• Mathematics

This technical mathematics article is written by Dr Chris Robbins of Grallator Limited. This article looks at Physical, biological and effective half-life and the mathematics behind them.

Physics is really nothing more than a search for ultimate simplicity, but so far all we have is a kind of elegant messiness

– Bill Bryson -