Question

4. Under what conditions a gamma ray “check source” could be considered a point source? What is the advantage of being able to approximate a source by a point source?

Answer 1

*A source can be assumed as point source depends on it's shape ,size, distance and energy. If the source has distance from the dose point three times larger than the it's maximum dimension, it's diameter is about few milimeter and length is about few centimeters and energy is between 0.2 to 2Mev.

*If we assume a source to be a point source then we can assume it to be a isotropic source i.e. energy can radiate in all direction uniformly and calculation is easier than any other size of source.