Fig. 1.

T cells within radiation treatment fields.

A) With radiation treatment made up of multiple overlapping fields focused on the tumor and involved lymph nodes, cells moving through the peripheral blood inside the treatment field will also be irradiated. The flow rates of cells through these vessels means that a large proportion are likely to pass beyond the field before treatment is complete. B) Subtypes of CD8 T cells within the tumor, lymph nodes, and blood, and estimates for the time these cells spend in each site depending on whether or not they meet their cognate antigen.^62,107