In a unit for acquiring dental radiographic images, an x-ray head (15) is rotationally coupled to a supporting arm (14) and is provided with an x-ray generating device (17), which is housed in an external casing (22 41) also containing an optical device (19) for collimating the x-rays output by the generating device (17), and is cooled by means of a cooling circuit (24 45) communicating with a cooling fluid source arranged outside the casing (22 41).
