[Which intensity modulated radiation therapy? From "step and shoot" to volumetric modulated arc therapy, point of view of the radiation oncologist]. / Quelle radiothérapie conformationnelle avec modulation d'intensité? De la technique "step and shoot" à l'arcthérapie, point de vue de l'oncologue radiothérapeute.

Intensity modulated radiation therapy (IMRT) offers optimal dosimetric and clinical results in terms of acute toxicity, allows augmenting the dose to the target volumes and therefore, appears promising for local control and disease-free survival. However, several pitfalls to this treatment are to be considered, namely a long treatment time and a high number of monitor unit (MU) required. The dosimetric results of the volumetric modulated arctherapy gives at least similar target coverage and preservation of organs at risk, while significantly reducing the number of required MUs and the overall treatment time. This has a potential impact on the treatment quality and the potential risk of secondary cancers. Volumetric modulated arctherapy allows implementation of stereotactic radiation therapy and complex treatments previously considered not feasible with IMRT. The future will involve this technology of high precision to determine the dose and to the target in real time using the image-guided radiotherapy. Tools combining these two methods are in development.