TI : A Study of the Focal Trough in Orthopantomograph
AU : Choi CH; Khim JD
AD : Department of Maxillofacial Radiology . School of Dentistry, Chosun University
SO : JKAOMFR. 1991;21(1):137-143
ISSN : 1225-049X
PY : 1990
LA : KOREAN
CP : KOREA
AB : In the study of the focal trough of panoramic radiograph using Panoura Eight-S (the Yoshida company), a series of 63 X-ray films were taken with the 8-19 metal pins placed in the holes of the plastic model plate and evaluated by 4 observers. The author analized the focal trough defined by the sharpness criteria and calculated dimension of focal trough in the horizontal plane.
The results were as follows;
1. Focal trough was not continued in the anterior region within a very high degree of sharpness.
2. With optional sharpness, the width of anterior and posterior focal trough was approximately 13mm and 60mm respectively.
3. The focal trough was narrow in the anterior region and was flared laterally with symmetry in posterior region.
4. Sharp image began to show at the position of 18mm posteriorly from the most anterior position of chin rest.