Interpretation of bilateral shadow nouns

Double echo: also known as bilateral shadow, refers to the low sound band on the gallbladder wall, which is formed by edema of the gallbladder wall and often occurs in the gallbladder wall of acute cholecystitis and ascites due to cirrhosis.

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The generation of bilateral shadows is mainly caused by oblique light. Therefore, grasping the following points can reduce bilateral shadows:

1, the midline, the midline is aligned with the third lumbar vertebra (that is, 3 cm above the iliac spine when lying on your side);

2. The film spacing, 90- 100cm, is too small, and the oblique effect is obvious;

3, the patient's position, should be the standard lateral position (that is, the coronal plane is perpendicular to the bed surface, the sagittal plane is parallel to the bed surface), at the same time, hands on the head, knees and hips bent;

4. The waist is flat.

The principles of bilateral production are as follows:

1.The X-rays emitted by the X-ray tube are tapered, the middle beam is the center line, and the surrounding beams are oblique rays.

2. When taking lumbar photography, the midline is aimed at the third lumbar vertebra, and oblique rays are aimed at other vertebral bodies. Because the oblique ray is aimed at other vertebral bodies, it produces oblique ray effect, which makes the images of other vertebral bodies skew and distort, not only produces bilateral shadows, but also produces vertebral body deformation.

3. Because the vertebral body has a certain thickness, it produces geometric amplification effect. The surface of the vertebral body near the bulb is larger than that far away from the bulb, and bilateral shadows can also be produced.

Therefore, when the center line is aligned with the third lumbar vertebra, the third lumbar vertebra can produce bilateral shadows without distortion. Other vertebral bodies can produce bilateral shadows or distorted shadows.