Removal of the Shadow of Cervical Vertebrae from Panoramic X-Ray Images with a Tomosynthesis Method

Abstract

The purpose of this study is to\rremove the shadow of cervical vertebrae from dental panoramic x-ray images with\ra tomosynthesis\rmethod and improve the contrast of details in both the teeth and jaw bones. To\rmeasure the shift-amount at each angular position that was required for\rreconstruction of panoramic x-ray images of the dental arch, strip images of a\rcalibration phantom were acquired. Then, a shift-amount table was prepared from\rthese images, and the other shift-amount table, which was used to reconstruct a panoramic image of the\rcervical vertebrae, was prepared by inverting the curve of the shift-amount\rtable upside down. Using these two tables, images focused on the dental arch\rand cervical vertebrae of a patient were made with the original strip data of\rthe patient. The shadow of the cervical vertebrae appearing on the image focused on\rthe dental arch was removed using the two above-mentioned images and blurring\rfunctions defined at two focusing geometries. The validity of the proposed\rmethod was evaluated with clinically acquired data of two patients. The\rshadow of the cervical vertebrae was successfully eliminated, and the contrast\rof the front teeth and detailed structures of the jaw bones was improved. The\rresults of the experiments showed that our proposed method was significantly\reffective in removing the shadow of the cervical vertebrae from conventional\rpanoramic x-ray\rimages.