What principle governs the dose distribution of sources in the Manchester system?

The principle that governs the dose distribution of sources in the Manchester system is based on geometric arrangement related to distance. This approach takes into account the inverse square law, which states that the intensity of radiation diminishes with the square of the distance from the source. As such, the Manchester system is designed to optimize the placement and distribution of radioactive sources to ensure that the prescribed radiation dose is delivered effectively while minimizing exposure to surrounding healthy tissues.

In this system, the arrangement of sources is carefully calculated based on clinical needs, the geometry of the tumor, and the characteristics of the radiation emitted. By considering the distance from each source to the targeted area, this method allows for a more precise and controlled dose distribution, providing a balanced approach to treating the tumor while safeguarding adjacent organs.

This spatial strategy contrasts sharply with other methods that might rely on uniform, binary, or random distributions, which do not take into account the critical factor of distance in relation to dose delivery. By focusing on the geometric arrangement and the principles of distance decay, the Manchester system represents a sophisticated approach to radiation therapy planning.