Abdomen

• Clinical indications for abdominal radiography

  • Ascites - accumulation of fluid in the peritoneal cavity, causing abdominal swelling
  • Pneumoperitoneum - air in peritoneal or abdominal cavity
  • Bowel obstruction
  • Ulcerative colitis – inflammation and ulceration of the colon and rectum
  • Intussusception – the telescoping of one part of the bowel into another
• Landmarks of the abdomen

  • Xiphoid process – T9/T10
  • Inferior costal margin – L2/L3
  • Iliac crest – L4/L5 vertebral interspace
  • Anterior superior iliac spine (ASIS)
  • Greater trochanter
  • Symphysis pubis
  • Ischial tuberosity

  
• Patient preparation


  1. After the patient is correctly identified, an outpatient should be instructed to remove long necklaces and all clothing except shoes and socks

  2. Patients should be checked for radiopaque objects that might obscure abdominal anatomy on the radiograph

  3. The radiographer should then obtain a pertinent patient history – to assist the radiologist in diagnosis and may help determine whether exposure factors need to be adjusted due to pathology

  4. Wear hospital gown provided with the opening in the back

  5. Briefly explain to the patient about the procedure and any necessary instruction in simple term
• Breathing instructions


  1. A significant problem relevant to abdominal radiography is motion

  2. Appropriate breathing instructions prevent voluntary motion

  3. To move the diaphragm upward and avoid compression of the abdominal organs, the exposure should be made during suspended expiration

  4. The patient should be instructed to "take in a breath…, blow it out…, and hold the breath out"

  5. Suspended expiration also reduced tissue thickness, thereby requiring less radiation to produce a diagnostic film
• Exposure factors


  • Abdomen is an area of low subject contrast – various organ tissue densities and the presence of radiolucent fat in the abdomen help to demonstrate specific abdominal structures
  • 70-80 kVp is usually employed because of the low subject contrast – to enhance the subject contrast, demonstrate soft tissue, and penetrate the abdomen
  • A correctly exposed radiograph will clearly demonstrate: the transverse processes of the vertebrae, the inferior margin of the liver, the kidneys, the psoas major muscles
• AP projection - supine position

  1. Film size – 14x17 in (35x43 cm), lengthwise

  2. Exp factors – kVp: 70 – 80 kVp

  3. FFD – 100 cm

  4. Assist the patient to the supine position on the radiographic table

  5. Place a pillow under the patient's head and position a small support under the patient's knee for comfort

  6. Adjust the long axis of the patient parallel with the long axis of the table; pull gently on patient's leg or under patient's arms to move and straighten the patient

  7. Center the median plane of the patient's body to the midline of the table

  8. Check for rotation of the pelvis by palpating the anterior superior iliac spines (ASIS) and ensuring they are equidistance from the table; use sponges for support and immobilization, if necessary

  9. Direct the CR perpendicular to the level of iliac crests

  10. Collimate to the abdominal walls laterally and to film size lengthwise

  11. Instruct the patient to take in a deep breath, blow it out, and hold it during the exposure
• Radiographic anatomy (structures seen on AP supine projection)

  • Liver
  • Psoas major muscle
  • Kidney
  • Transverse process
  • Iliac crest
  • Symphysis pubis
• Evaluation criteria for AP supine projection

  • The symphysis pubis and lateral margins of the abdomen should be included within the collimated area
  • The renal shadow, psoas major muscles, transverse processes of the lumbar spine, and inferior margin of the liver should be clearly visualized on a properly exposed abdominal radiograph
  • Asymmetry of the iliac crests and ischial spines indicates rotation of the pelvis; the narrower ilium would have been elevated
  • Unless pathology is present, the spine should be straight and centered to the film

  
• AP projection - erect position

  1. Film size – 14x17 in (35x43 cm), lengthwise

  2. Exp factors – kVp: 70 – 80 kVp

  3. FFD – 100 cm

  4. Upright, legs slightly spread, back against grid device

  5. Arms at sides away from body

  6. Midsagittal plane of body centered to midline of erect Bucky

  7. Do not rotate pelvis or shoulders by palpating the anterior superior iliac spines (ASIS) and ensuring they are equidistance from the Bucky

  8. Adjust height of IR so the center is approximately 5 cm above iliac crest (to include diaphragm), which for the average patient will place the top of the IR approximately at the level of the axilla

  9. Direct the central ray to a point approximately 5 cm above the level of the iliac crests

  10. Center the cassette to the central ray; the top edge of the cassette should be at the level of the axilla

  11. Collimate closely on all four sides; DO NOT cut off upper abdomen

  12. Instruct the patient to take in a breath, blow it out, and hold it out during the exposure
• Radiographic anatomy (structures seen on AP erect projection)

  • Diaphragm
  • Psoas major muscle
  • Air-fluid levels
  • Kidneys
  • Iliac crests
• Evaluation criteria for AP erect projection

  • The diaphragm and lateral margins of the abdomen should be included within the collimated area
  • Air-fluid levels should be adequately exposed and demonstrated
  • Asymmetry of the iliac crests indicates rotation of the pelvis; the narrower ilium would have been elevated
  • Unless pathology is present, the spine should be straight and centered to the film

  
• Film Specifics


  • Name of Patient
  • Age & Date of Birth
  • Location of Patient
  • Date Taken
  • Film Number (if applicable)
• Initial assessment of an AXR


  • Same as for a CXR
• Most common basic and special projections of abdominal x-ray

  • BASIC: AP supine, AP erect
  • SPECIAL: PA prone, Lateral decubitus, Dorsal decubitus, Lateral

  
• Pathology demonstrated


  • Abdominal masses, air-fluid levels and possible accumulations of intraperitoneal air
• Patient should be on side a minimum of 5 min before exposure (to allow air to rise or abdominal fluids to accumulate); 10 to 20 mins is preferred, if possible for best visualization of potentially small amounts of intraperitoneal air
• Left lateral decubitus best visualizes free intraperitoneal air in the area of the liver in the right upper abdomen away from the gastric bubble
• Technical factors


  • IR size 35x 43cm lengthwise
  • Moving or stationary grid
  • 70 – 80 kVp and SID 100cm
  • 20-30 mAs
• Patient position


  1. Lateral recumbent on radiolucent pad, firmly against vertical grid device

  2. On firm surface such as a back board, positioned under the sheet to prevent sagging and anatomy cutoff

  3. Knees partially flexed, one on top of the other to stabilize patient

  4. Arms up near head, clean pillow provided
• Part position


  1. Adjust patient and cart so that the center of IR and CR are approximately 5cm above iliac crest (to include diaphragm)

  2. Ensure no rotation of pelvis or shoulders

  3. Adjust height of cassette to center of MSP to center of IR but ensure that upside of abdomen is clearly included on the IR
• Central ray


  CR horizontal, directed to center of IR, at about 5cm above level of iliac crest; use of a horizontal beam to demonstrate air-fluid levels and free intraperitoneal air
• Collimation


  Collimate on four side; do not cut off upper abdomen
• Respiration


  Make exposure at end of expiration
• Structures shown


  • Air-filled stomach and loops of bowel and air-fluid levels where present
  • Should include bilateral diaphragm
• Position


  • No rotation: iliac wings appear symmetric and outer rib margins are the same distance from spine
  • Spine should be straight, aligned to center IR
• Collimation and CR


  • Collimation borders to IR margins to prevent cutoff of essential anatomy
  • CR approximately 5 cm above the level of iliac crest
• Exposure criteria


  • No motion: ribs and all gas bubble margins sharp. Exposure sufficient to visualize spine and ribs and soft tissue but not to overexpose possible intraperitoneal air in upper abdomen
  • Slightly less overall density than supine abdomen
• Pathology demonstrated


  • Abdominal masses, accumulations of gas, air-fluid levels, aneurysm, calcification of aorta or other vessels and umbilical hernias
• Technical factor


  • IR size 35 x 43cm lengthwise
  • Moving or stationary grid
  • 100-120 kVp, 30-40 mAs
  • SID 100cm
• Use gonadal shielding on males
• Patient position


  1. Supine on radiolucent pad, side against vertical grid device; secure cart so that it does not move away from grid device

  2. Pillow under head, arms up beside head, support under partially flexed knees may be more comfortable for the patient
• Part position


  1. Adjust patient and cart so that the center of IR and CR is 5cm above iliac crest

  2. Ensure no rotation of pelvis or shoulders exist (both ASIS should be the same distance from tabletop)

  3. Adjust height of IR to align MCP with centerline of IR
• Central ray


  CR horizontal to center of IR 5cm above iliac crest and to MCP
• Collimation


  Collimate to upper and lower abdomen soft tissue borders
• Respiration


  Exposure is made at end of expiration
• Structures shown


  • Diaphragm and as much of lower abdomen as possible should be included
  • Air-filled loops of bowel in abdomen with soft tissue detail should be visible in anterior abdomen and in prevertebral regions

  
• Position


  • No rotation as evident by superimposition of posterior ribs and posterior borders of iliac wings and bilateral ASISs
• Collimation and CR


  • Collimation borders to tissue margins of anterior and posterior abdomen. Center of collimation field to prevertebral region 5cm above level of iliac crest
• Exposure criteria


  • No motion; rib and gas bubble margins appear sharp. Lumbar vertebrae may appear about 50% underexposed with soft tissue detail visible in anterior abdomen and in prevertebral region of lower lumbar vertebra