Abdominal X-ray - System and anatomy
Image data and quality
Key points
- Check the patient details
- Check which projection has been used - AP or decubitus
- If assessing for perforation always look at the ERECT chest X-ray
- Check you can see the whole abdomen
Patient and image data
You should always check that the image data refers to the correct patient and that the X-ray is the current examination.
Check the image data to see if it is a standard Anterior-Posterior (AP) supine projection.
Supine Anterior-Posterior (AP) projection
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Supine Anterior-Posterior (AP) projection
- Abdominal X-rays are usually acquired using an AP (Anterior-Posterior) projection (X-rays pass through the patient from front to back), with the patient positioned supine.
If perforation of the bowel is suspected then an ERECT chest X-ray must be requested. This is the most sensitive plain radiographic study to detect the presence of free gas in the abdomen.Erect chest
X-ray
Erect Chest X-ray - Pneumoperitoneum
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Erect Chest X-ray - Pneumoperitoneum
- Pneumoperitoneum (free gas in the abdomen) does not always indicate perforation of an abdominal viscus.
- This patient had an abdominal operation shortly before this image was acquired, which accounts for the free gas seen under the diaphragm.
Occasionally patients are too ill to be positioned erect. In this case a CT scan may be appropriate, or a 'decubitus' radiograph can be obtained. For a decubitus image the patient lies on their side and X-rays pass through the body from back to front. For a 'left decubitus' the patient lies on their left.Other projections
Decubitus positioning
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Decubitus positioning
- Use of the decubitus position can demonstrate pneumoperitoneum in a patient who cannot be positioned for an erect chest X-ray to be performed. Gas rises to the upper part of the abdomen and so will be seen on one side of the abdominal X-ray image.
- This projection is not commonly performed.
Abdominal X-rays provide limited information at the best of times. Often anatomical structures are not clearly demonstrated, and abnormalities can be obscured by normal anatomical structures. For example, small renal stones may be obscured by overlying bowel. When an image is
of low quality there is often little that can be improved and therefore repeating images is usually unfruitful. The whole abdomen should be included. Often two images are required to view the entire abdomen from the diaphragm to the hernial orifices, and from left to right abdominal walls. Large patients may require more images.Abdominal X-ray quality
Which of the following might be used to demonstrate a pneumoperitoneum?
A. upright, AP projection
B. Left lateral decubitus
C. Dorsal decubitus
D. All of the above
What are the membranes that line the wall of the Abdomen?
Peritoneum and Retroperitoneum
What two layers consist of the Peritoneum?
What cavity is postrior to the Peritoneum?
What two organs lie in the space of the Retroperitoneum?
What do you want to see in an Abdominal Image, High contrast or Moderate contrast?
What are some Radiation Protection procedures regarding Abdominal Images?
-Shielding pediatric patients & patients of reproductive age
-Close
collimation
-Optimum technique factors
Essential Projections for Abdomen
-AP supine and upright positions
-PA upright position
-Lateral
-Lateral, R or L dorsal decubitus position
-AP/Lateral Decubitus
What positions does the 3-way abdomen or acute abdominal series consist of?
-Ap supine
-AP upright
-PA Chest
What is another common request for Abdomen procedures?
Two-view abdomen series consisting of AP supine and AP upright
If a patient can not stand for an upright position, what do you do?
Position patient in Left lateral Decubitus
AP Supine is often referred to as what?
Kidneys, Ureters, and Bladdar
Positioning for AP Abdomen supine
Supine, without rotation and support knees to reduce strain of back
Where is the IR centered for AP supine?
Centered at the level of iliac crests (check that pubic symphysis is included)
How is the CR in relation to the IR in an AP supine position?
-CR is perpendicular to the IR
-Enters patient on MSP at level of iliac crests
-MSP is perpendicular and MCP is parallel
How can you tell if pubic symphysis is included in an AP supine?
Feel for Greater Trochanter; this is in alignment w. the pubic symphysis
Mesentery and Omentum (folds)
The folds of the peritoneum that function to support the viscera of the abdomen in position
To which level of the patient should the CR be centered for the KUB?
For the AP upright abdomen image of an adult of average size, why should the centering be slightly higher than the centering level used for the supine KUB image?
Why is it desirable to include the diaphragm in the upright Abdomen image?
To demonstrate free air in the abdomen
Which projection does not demonstrate free air levels within the abdomen?
a. AP supine
b. AP upright
c. Lateral, dorsal decubitus
d. AP, left lateral decubitus
What is the major advantage of the PA projection of the abdomen over the AP projection of the abdomen?
PA projection reduces the exposure to the gonads
What is pneumoperitoneum?
Presence of air in the peritoneal cavity
Where do you center the IR for Decubitus position?
where do you center the IR for Upright positiono?
What does a three-way abdomen (acute abdominal) series demonstrate in the abdomen?
Abdominal contents, presence of free air, and air fluid levels
Why would a 3 Abdominal series be ordered?
To evaluate bowel gas or to rule out free air, bowl obstruction, and infection in abdomen
How can you evaluate rotation on a KUB?
AP ABDOMEN SUPINE
1. Alae or wings of the ilia should be symmetric.
2. If seen, ischial spines of the pelvis should be symmetric
3. Spinous processes should be in the center of the lumbar vertebrae.
How can you evaluate rotation on a KUB?
AP ABDOMEN SUPINE
1. Alae or wings of the ilia should be symmetric.
2. If seen, ischial spines of the pelvis should be symmetric
3. Spinous processes should be in the center of the lumbar vertebrae.
Patient position for AP upright
-Standing upright, w. back in contact w. vertical grid
-MSP centered to grid
-weight distributed equally on both feet
If you need to include the bladdar in an AP upright position, where do you center the IR?
Center IR to the iliac crest
When is PA done instead of AP?
When thinking about dose; when trying to minimize dose thyroid, breasts, etc.
Left Lateral Decubitus Position
*Performed in place of upright position for patients who are too ill to stand
- Patient in recumbent left lateral
- Arms up and out of the way
- Knees bent
- Center iliac crests to IR or 2 in above
CR alignment for Left Lateral Decubitus
Directed Horizontal and perpendicular to center of IR
-MSP is perpendicular to IR and MCP is parallel
Lateral Abdomen Patient Position
-Recumbent right or left lateral
-knees bent to increase stability and comfort
-bent elbows and place hands under head
Where is IR centered in the Lateral Abdomen?
At level of iliac crests or 2 in above if diaphragm is included
-Perpendicular to IR
-Enters on MCP at level of crest or 2 in above crests
--MSP
parallel to IR and MCP is perpendicular
What position is used if patient cannot stand or lie on their side?
Lateral Abdomen, Dorsal Decubitus
Describe Lateral Dorsal Decubitus
- Patient lies on
- horizontal x-ray beam
-Arms crossed on upper chest or behind head
-Support knees for comfort
-Center 2 in above iliac crests to IR
CR for Lateral Abdomen, Dorsal decubitus
-Horizontal and
perpendicular to center of IR
-MSP is parallel to IR and MCP is perpendiculara
-Enters MCP at 2 in above iliac crests
Image evaluation of AP Supine
-Evidence of proper collimation
-Area from pubic symphysis to the upper abdomen
How to identify proper alignment for AP supine?
-Centered vertebral column
- Ribs, pelvis, and hips equidistant to the edge of image
What is pneumoperitoneum?
abnormal presence of air or other gas in the peritoneal cavity
The abdominopelvic cavity is enclosed in a double-walled seromembranous sac called ....
What are the tissue structures that are used to determine effective technique?
Lower liver border, psoas muscles, kidneys, ribs, and transverse processes of lumbar vertebrae
What positions have the CR directed horizontal and perpendicular to the center of the IR?
-Lateral, dorsal decubitus
-Left lateral decubitus
What position has the CR horizontal and 2 in. above the iliac crest?
-AP upright
-PA upright
-Dorsal Decubitus
-Left Lateral Decubitus
How is the CR displayed in relation to the IR in an AP supine position?
CR is perpendicular to the IR at level of iliac crests
-MSP is perpendicular and MCP is parallel
How is the CR displayed in relation to the IR in a PA upright?
CR is directed
horizontal and perpendicular to the center of the IR
-MSP is perpendicular and MCP is parallel
How is the CR displayed in relation to the IR in a Lateral Projection?
Perpendicular to the IR and entering the MCP plane at iliac crest level or 2 in. above iliac crest level
-MSP is parallel to
IR and MCP is perpendicular
How is the CR displayed in relation to the IR in a Dorsal Decubitus position?
CR is directted horizontally and perpendicular to the center of the CR.
-MSP is parallel to IR and MCP is perpendicular
In an acute abdomen series (three-way seriess), what image should be substituted for the upright abdomen radiograph when the patient is unable to stand?