3.3.2. The low and repeated doses effect Preliminary results from our lab indicate that X-ray DSB induced by two identical high doses (e.g; 1 Gy) separated by a time inter-val ranging from minutes to hours) are repaired more slowly than after 2 Gy in human primary fibroblasts. Similar observations have been performed on doses up to 2 mGy (Colin et al., 2011).Between the two doses, during some minutes, there is no significant repair of DSB, but initial SSB may be repaired and secondary SSBdue to BD excision can appear and increase the chromatin decondensation. Such a chromatin decondensation may make slower theDSB repair process and lead to the accumulation of unrepairedDSB. Such accumulation of unrepaired DSB may be at the originof the production of multi-aberrant (rogue) cells. In 2011, to assess in vitro mammographic radiation-induced DNA damage in mam-mary epithelial cells from 30 patients with low (LR) or high (HR)family risk of breast cancer, radiation-induced DSB were quanti-fied by using H2AX immunofluorescence in different conditions of mammography irradiation: the dose repetition (2 + 2 mGy) pro-vided more induced and more unrepaired DSB than 4 mGy at onetime, and was exacerbated in HR patients. This study highlights theexistence of a LOw and Repeated Dose (LORD) effect. These find-ings may lead us to re-evaluate the number of views performed inscreening using a single view (oblique) in women whose mammo-graphic benefit has not properly been proved, such as HR patients(Colin et al., 2011). Some other manifestations of the deleterious effect of repeated doses have been published. The so-called “W”effect is one of the most representative examples. From a linear