Cephalometric image
The lateral X- ray image (syn: FRS, profile X-ray image) is an X- ray image that is mainly used in orthodontics and oral and maxillofacial surgery . For treatment planning, growth tendencies, jaw and bone relationships and the axes of the anterior teeth are determined .
It is a laterolateral image of the skull with the beam path as parallel as possible . The distance between the radiation source and the X-ray film is therefore around 1.5 meters; the distance between the head and the X-ray film is chosen to be as small as possible. The recording time is approx. 12 seconds. During this time, two diaphragms with a vertical slit move synchronously over the radiation source and the film. This results in the film being exposed in a vertical line from anterior to posterior (from right to left in the picture shown here). By using soft tissue filters, the individual sections of the X-ray image can be exposed to different degrees. Therefore, both the relatively radiolucent soft tissues of the facial profile and the relatively radiopaque bones can be seen in the same image .
The picture is taken either with conventional X-ray film or with a digital sensor. The radiation exposure per exposure depends on the size of the patient (the tissue to be irradiated) and the technology used. By using digital X-ray technology , the radiation exposure with FRS can be halved. The effective dose is given as 2.3 µSv for conventional and 1.1 µSv for digital recordings. Due to the development of increasingly sensitive sensors, the quality of the images is improved and the required radiation dose is lower.
In addition to the structures of the facial skull, parts of the cervical spine are also shown on the FRS . Based on the size and shape of the individual vertebrae, conclusions can be drawn about the degree of maturity in children and adolescents and thus about the expected growth. In the specialist literature this is referred to as CVM (cervical vertebra maturation). This may mean that a hand x-ray can be dispensed with.
evaluation
The evaluation of the FRS by measuring different points, distances and angles is called cephalometry . There are over 100 different analysis methods available, with the Ricketts or Hasund methods being the most common. Since the beam path is only almost parallel and the film or sensor is located behind the object, the object is usually shown slightly enlarged on the FRS. The installation of a radiopaque scale in the nasal support enables subsequent calibration , so that not only angles but also distances can be measured in millimeters.
prosthetics
In prosthetics , this X-ray can be useful for planning a reconstruction of cases of abrasion and for total prostheses . The cranial parameters to be determined with it provide valuable information on the positioning of individual teeth and entire groups of teeth.
The FRS was introduced by Rudolf Slavicek based on the SAM articulator in the 1980s; Meanwhile there are over 100 analysis methods for the objective determination of occlusal planes , bite height, etc. Occlusal curve with the aim of optimally defining the occlusal plane and bite height from a functional and cosmetic point of view as well as identifying the causes of functional disorders of the temporomandibular joint and muscular tension. As part of the functional diagnosis, this X-ray image is combined with electronic joint recording to determine the occlusal plane .
Individual evidence
- ↑ Pasler, FA: Dental Radiology , Thieme, 3rd edition ISBN 3-13-604603-X
- ↑ Visser, H. et al. (2001): Dose reduction by direct-digital cephalometric radiography . In: Angle Orthod . 2001 Jun; 71 (3): 159-63. PMID 11407766
- ↑ Baccetti, T. et al .: An improved version of the cervical vertebral maturation (CVM) method for the assessment of mandibular growth . In: Angle Orthod . 2002 Aug; 72 (4): 316-23. PMID 12169031
- ^ Al Khal, HA et al .: Elimination of hand-wrist radiographs for maturity assessment in children needing orthodontic therapy . In: Skeletal Radiol . 2008 Mar; 37 (3): 195-200. Epub 2007 Oct 3rd PMID 17912521
- ↑ Dental Knowledge Lexicon
- ↑ RHEINBACHER REIHE dental TRAINING
