IMRT

The dose-volume is generally a mixture of two extreme situations of cell organization patterns:

parallel organs , whose functionality is highly impaired, causing a complication, when irradiating a significant percentage of the total volume late reactions, e.g. lung, liver, kidney, parotids acute reactions e.g. mucositis late reactions, e.g. nervous system, paralysis serial organs , where reaching a well defined dose level severely impairs the organ functionality, meaning that there is only a small volume effect

More correct to characterize organs in terms of their organ reserve