The hypothesis to explain lattice radiotherapy mechanism: pink line delineates global tumor volume, the yellow line shows the necrotic core, and red spheres represent high dose regions and are approximately located at the boundary between the necrotic and normoxic areas (hypoxigenated interface) to radially elicit the bystander effect (blue arrows), accurately avoiding high dose delivery in the green strip due to the hazardous closeness of bowel (Organ At Risk: OAR).