Patient preparation is extremely important for ensuring that a high-quality image is produced and that errors are avoided (Table 3). For instance, incorrect patient preparation can lead to "ghost images" which can render the radiographic image undiagnostic. While ghost images often occur due to metallic objects, they can also occur due to anatomical structures located outside the image layer or focal trough. Ghost images always appear higher and distorted on the opposite side of the radiographic image (see Figure 4). Some errors are unavoidable due to the patient’s stature, facial asymmetry, or difficulty following instructions.8
Table 3. Patient Preparation Guidelines.
|All necklaces, piercings (earrings, tongue rings, etc.) and jewelry in the head and neck regions need to be removed prior to exposure.
|Items such as headbands, bobby pins, hair clips, hearing aids, etc. must be removed prior to exposure. Removable partial dentures and orthodontic appliances should be taken out prior to imaging.
|Apron must not have a thyroid collar and should be placed properly so it does not block the x-ray beam.
An important item to include when preparing the patient is the use of a lead apron, which is recommended for all radiographic procedures. Lead aprons help provide protection for radiosensitive tissues in the neck, chest, reproductive areas, and blood forming tissue. In addition, lead aprons stop nearly 98% of scattered radiation from reaching reproductive organs. There are lead-free aprons that use an alloy material instead of lead. They are 50% lighter and safer for patients and clinicians because they are lead-free.9
While thyroid collars are not indicated for panoramic imaging, they are effective for use during intraoral imaging, because they have been shown to stop 92% of scatter radiation9 One study revealed that only 2% of the general dentists surveyed report using a lead apron with a thyroid shield prior to taking radiographs.7
Figure 4. Appearance of Ghost Image.
Image source: BR L. Iwata, DDS
The patient’s earrings were not removed prior to imaging. Therefore, a ghost image is present. In the example, the image of the actual left earring is on the right side and the ghost image of the left earring is on the left side of the image. Ghost images appear distorted, higher, and on the opposite side of the panoramic radiograph. The other error that can be observed in the panoramic image, is that the chin is too low. This causes the spine to be more pronounced on both sides of the image.