With respect to Ionising Radiation, a line source describes a Radioactive source which can be represented by a line between points A-B in any chosen plane. Calculations of Dose Rates from line sources are more complicated than those from Point Sources and in many cases, direct measurements are going to always be preferable. Such calculations usually involve knowing (or estimating) the Activity per unit length of the source, then calculating the dose rate at a chosen point by integrating contributions from integral points along the line. Commercial programs such as Microshield can undertake this process automatically.