This invention relates to dental radiation imaging systems, and in particular to systems for positioning a patient with respect to a radiation source and detector so as to produce panoramic images.
Panoramic dental radiation imaging is used to obtain images of a patient's teeth in an orthogonal manner. Since the dental arch is not a circular shape, the rotation of the arm to which the radiation source and detector are attached must be adjusted in the course of the imaging in order to achieve the proper orthogonal imaging. Conventional panoramic radiation apparatuses are characterized in that the radiation source is arranged to orbit about the patient's skull, whereby the dental arch can be imaged by means of a radiation detector orbiting on the opposite side of the skull. The function of the rotating mechanism of a panoramic radiation apparatus is to direct the radiation beam through the patient's jaw at a desired angle and to keep the radiation detector at a particular distance and orientation with respect to the object being imaged.
The radiation source of the panoramic radiation system and the rotating mechanism of its radiation detector must be capable of forming an image of the dental arch. During the rotational movement, the center of rotation is moved in order to ensure orthgonality of the radiation beam on the dental arch, constant magnification, and continuity of motion. The rotating mechanism must be able to accomplish the desired orbital movement of the center of rotation in a horizontal plane and provide vertical support to the entire apparatus so that the desired orbit can be implemented with accuracy. Such orbital movement can be achieved by virtue of different conventional rotating mechanisms, such as those disclosed in U.S. Pat. Nos. 4,741,007 and 6,466,641.
Also important is the proper positioning of a patient with respect to the radiation imaging apparatus, such that the rotation of the radiation source and detector about the patient's skull is in proper alignment with the dental arch. Also, in order to ensure a clear image, the patient must remain still during the imaging. Conventional mechanisms for patient positioning include platforms on which a patient may place his chin, such as that shown in U.S. Pat. No. 6,466,641. However, while these types of platforms aid in proper vertical alignment (along the Z axis) of the skull to adjust the height of the radiation source and detector, it does not provide for proper forward-backward positioning (the Y axis), positioning in right-left direction (the X axis), stabilizing the patient in the apparatus, or providing a convenient way for a technician to assess proper positioning. Other conventional systems may include arms to guide the top of the head, such as those shown in U.S. Pat. Nos. 5,511,106 and 6,510,196. Again, while these mechanisms may provide for position in one or more of the X, Y, and Z axes, neither provides positioning in all three directions, along with stabilization of the patient and easy assessment of position by the patient and or the technician.
The present invention relates to improvements to the apparatus described above and to solutions to some of the problems raised or not solved thereby.