Vatech GREEN SMART, User Manual

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15. Appendices
182 Green Smart User Manual
Lateral Left-Right Positioning Error
When the arches are positioned incorrectly in the lateral left-right dimension, the posterior
teeth on one side will appear broad or widened, while the teeth on the other side will
appear narrowed or diminished in width and severely overlapped
(Figure 4) . This image
distortion is similar to that which occurs with an incorrect anterior-posterior position. When
the arches are rotated or tilted, the posterior teeth on one side move out of the focal
trough to a position further away (back) from the image receptor, while the opposite side
simultaneously moves closer (forward) to the image receptor. Depending on the severity
of rotation or tilting, the inferior border of the mandible will appear distorted, and the
condyles and rami will appear asymmetrical.
To avoid imaging errors that result from incorrect lateral positioning, the midsagittal plane
must be positioned perpendicular to the floor. Most panoramic x-ray machines have a
head positioner and/or laser light beam guide, along with a mirror, to assist in determining
the correct lateral head position. The pediatric patient may need additional instructions to
maintain the correct position throughout the exposure.
Movement of the tube head during exposure may pique the pediatric patient's curiosity,
causing the head to rotate as the eyes follow the movement of the tube head. A vertical
line decal affixed to the mirror can serve as a visual aid and a focus point. An eye-
catching sticker, such as those purchased from a craft store, can be adhered to the mirror
in a position that aligns with the midsagittal plane. The patient can be directed to position
the head so that the sticker appears at the tip of the nose and to maintain focus on this
reflection throughout the exposure. Pediatric patients may find looking at themselves in
the mirror entertaining and a fun way to participate in the process.
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