Introduction As part of the service quality assurance program, the implementation of 4D imaging required the implementation of a new quality control. The main idea was to evaluate the restitution of the shape, volume and position of a moving object through the CT4D imagery performed on the AS OPEN DEFINITION (SIEMENS) device. For this study the creation of a mobile object was necessary. For its low interaction with the RX, its simplicity of use, and its multiplicity of solutions, the technology LEGO® was retained. Methods Equipment ♣ Scanner: SOMATOM Definition AS (Open 20 RT) ♣ Detecteur de respiration: Systeme ANZAI AZ 733 VI ♣ Fantome: LEGO® (Brick, Technic et Power Functions) 6 movements (Long, Lat and 4 hysteresis 2D) were programmed and imaged in CT4D (10 phases, MaxIP, MinIP and Average), in 1 and 2 mm. The analysis of the shape and volume of the object was made by comparing the CT image analysis of the immobile object. The analysis of the trajectories was carried out by comparing the reading (ppm) of the trajectories and the positions of the center of the object deduced from the CT4D imagery (10 phases, MaxIP, MinIP and Average. Results The average deviations observed on the 10 phases are quite dispersed, in exploration of 1 mm as in 2 mm, but of comparable values. The deformation of the object, observed in the different phases, reflects these variations. Conclusions This study enabled us to postulate the necessary and sufficient cutting thickness (2 mm) to be programmed during 4D acquisitions and to validate the synchronization of the respiratory signal with the bidirectional trajectory (longitudinal and lateral) of a moving object. It will still evolve this ghost by implementing anteroposterior movement.