Orthopantomography

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Orthopantomogram of a mixed dentition
Adult OPG

An orthopantomogram ( OPT or OPG , more rarely OPTG ), also known as a panoramic layer image ( PSA ), is a two-dimensional X-ray image of the upper and lower jaw in the form of a semicircle from one ear to the other. It is a standard procedure in dental radiography and allows a diagnostic x-ray of the upper and lower jaws of humans , all teeth , the adjacent jaw areas, both temporomandibular joints and the right and left maxillary sinus are shown. The OPT also detects the lateral neck area , so that hardening of the arteries in the large carotid arteries can also be diagnosed.

history

Numata's scheme of panoramic radiography
An OPT device in start position

The Japanese Hisatugu Numata developed the first panoramic X-ray machine in 1933/34. Yrjö Veli Paatero (1901–1963) from Finland developed the Numata technology together with the engineer Timo Nieminen and initially gave the device he developed the name “Parabolography”, which he changed to “Pantomography” in 1950, before moving in 1958 at the suggestion of Japanese Eiko Sairenji coined the name "Orthopantomography" (OPG). The first of these devices was obtained from Palomex , Finland under the trade name Orthopantomography marketed with the name "panorex" in 1961 by the company SS White.

The OPT device

DXIS (Direct X-ray Imaging System)
in real-time display

The recording device, called orthopantomograph or OPT device , uses the X-ray technology of X-ray tomography , which is widely used in medicine : The recording unit with a film cassette or a digital line camera moves around the patient's face from behind and writes on during the recording this way a little more than a semicircle . The X-ray tube synchronously moves around the head from right to left around the back of the head. The X-ray tube is built in such a way that it emits a wedge-shaped, vertical bundle of rays, which expands from about 0.25 mm to about 3 mm. This beam illuminates the jaw portions, and finally passes through a vertical slit in one of the film cassette upstream shield plate of lead . Behind it is the fixed line camera or the cassette moves slightly more slowly in its direction of travel than the rest of the apparatus, which means that the image of vertical stripes is recorded on the film. At the end of the journey, the cassette finally lags behind the carrier by its own length, exposing its entire length through the gap. As an alternative, the individual lines of the line scan camera are combined to form a digital OPT. It is therefore a tomography in which a curved, approximately semi-elliptical surface is projected onto the film plane, rather than a flat one .

Diagnosis

Primarily, OPG recordings are used to provide an overview, therefore, for a rough diagnosis, for example whether teeth are displaced, retained or not created. Changes in the jawbone can also be seen, and often the course of the mandibular nerve . Numerous secondary findings can be recorded. The central area of ​​the image is shaded by a procedural overprojection of the cervical spine, especially in the anterior region. Likewise, the root tips are often shaded by an overprojection of the bony palate. As a result, these areas are indistinctly depicted and not accessible for precise diagnostics.

Radiation exposure

In Switzerland, natural and civilizing radiation lead to an annual average exposure of 4 mSv per inhabitant. Dentistry accounts for just 0.01 mSv (1% of medical X-ray diagnostics) in the total exposure. The creation of an X-ray status using analog dental films was opposed to the higher radiation exposure compared to the OPG. The radiation exposure of a single dental film x-ray is approximately 2.1 to 5.5  µSv . With digital recording technology, the radiation exposure is only about 0.2 to 1.0 µSv, which is significantly less than that of the OPG with about 19 µSv. Even if the effective dose in the 14-image dental film status and its share in the total exposure is very low, relatively high local doses (especially on the skin) are applied; the indication of only the effective dose obscures this.

For comparison: When traveling by air at a height of 10 to 12 km, the radiation exposure is around 5.5 µSv per hour.

Web links

Commons : OPG Recordings  - collection of images, videos, and audio files

Individual evidence

  1. ↑ Durgesh M. Bailoor: Fundamentals of Oral Medicine and Radiology . Jaypee Brothers Publishers, 2005, ISBN 978-81-8061-514-6 , pp. 313- ( google.com ).
  2. ↑ YV Paatero: Pantomography use in theory and. In: Acta radiologica. Volume 41, Number 4, April 1954, pp. 321-335, PMID 13158133 .
  3. ↑ Leyli Behfar, "Distortions" caused by incorrect positioning of the panoramic layer image , dissertation, 2005. Accessed on March 9, 2015.
  4. ↑ Textbook of Dental and Maxillofacial Radiology by Karjodkar . Jaypee Brothers Publishers, 2006, ISBN 978-81-8061-854-3 , pp. 20 ( google.com ).
  5. ^ From Paatero to 3D , Palomex Group. Retrieved July 20, 2015.
  6. ↑ Dieter Beyer, Michael Herzog, Friedhelm Zanella, Klaus Bohndorf, Eberhard Walter, Alfons Hüls: X-ray diagnosis of dental and jaw diseases: a clinical-radiological concept . Springer Berlin Heidelberg, 2013, ISBN 978-3-642-71063-6 , pp. 7-13 ( google.com ).
  7. ↑ A. Aroua, B. Burnand et al. a .: Nation-wide survey on radiation doses in diagnostic and interventional radiology in Switzerland in 1998. In: Health physics. Volume 83, Number 1, July 2002, pp. 46-55. PMID 12075683 .
  8. ↑ Michael Hülsmann: Endodontics . Georg Thieme, 2008, ISBN 978-3-13-156581-5 , p. 85- ( google.com ).
  9. ↑ J. Th. Lambrecht, Radiation exposure from analog and digital racks and panoramic film recordings Switzerland. Monthly Zahnmed 114: 687-693 (2004)
  10. ↑ Claus Grupen: Basic course on radiation protection . Springer, 2008, ISBN 978-3-540-75849-5 , pp. 176- ( google.com ).