IMRT

Tissue architecture (1)  Normal organs are composed of multicellular ”functional subunits” FSU (ex: nephrons in kidney, alveolus in lung)  A FSU is the tissue volume which can be regenerated by a single stem cell. FSU are defined for tissue repair purposes Withers et al, IJROBP, 1988

 Organ function depends on the ”aggregation” of cells into functional subunits

 Radiation response of an individual FSU depends on the properties of the cells (radiosensitivity, regenerative capacity) and on the number of stem cells in a FSU