This communication forms part of the articulation of two research programs carried out within the Social Human Sciences Research Laboratory of the Institute for Radiation Protection and Nuclear Safety (IRSN). The first is concerned with transversal organizations (processes, supply chains, etc.) and the complex nature of performance (safety, security, quality, etc.) in these organizations which are characterized by a fragmentation of the activity. The second analyzes the way in which technologies are integrated into the activity of actors and to what extent they allow this activity to develop. These two research programs come together in particular around the concept of “organizational genesis” (Folcher & Bationo Tillon, 2018, 2019; Bationo-Tillon, Poret & Folcher, 2020; Folcher, Bationo-Tillon, Poret & Couillaud, 2021). This concept is presented here from a research carried out in the field of radiotherapy. In this area, advances related to the development of computing and imaging have played and continue to play an essential role in the evolution of treatments. At the same time, these advances, which are experiencing a sustained rate of development, raise the question of their appropriation by radiotherapy professionals, directly linked to that of patient safety. Indeed, if these advances contribute to the quality of treatments, they can also bring out new risks for patients. Understanding the process of appropriation of a technical novelty is at the heart of the research presented here. Starting from this focus on the relationship between the actors and the technique, our results show that the introduction of the technical novelty has effects not only on the individual level, but also on the radiotherapy treatment process as a whole. In other words, from an analysis of the appropriation which could be similar to an analysis of the Human-Machine interaction, our research has highlighted the way in which a modification of the technical system leads to modifications at the level of the cross-functional collective activities (Poret, Folcher, Motté, Haradji, 2016) founding the organization. With the concept of organizational genesis, which allows this passage between different levels of understanding, our research conceptually anchored in French-speaking ergonomics meets the objectives of macroergonomics (Carayon, Karsh, Gurses, Holden, Hoonakker, Hundt, Montague, Rodriguez, Wetterneck, 2013; Kleiner, 2008). We hope that this communication, and the concept of organizational genesis presented therein, will open up discussions between two ergonomic traditions - French speaking ergonomics and macroergonomics, which present numerous complementarities for the analysis and design of organizations.