Materials for Existing Clients - Guidelines - DXA Guidelines

Scan modes for Hologic users

Hologic users have the choice of 2 different scan modes. These scan modes each differ in length:

  1. Array (a)
  2. FastArray (f)

Example: A whole body scan acquired in Array will appear as "Whole body" on the printout

If a patient is very large, they should be scanned using Array (a) scan modes to ensure image quality. Longer scan times allow more time for image acquisition and provides clearer images. *The same scan mode should be used at baseline and at each of the time points that follow.

Acceptable Femur image

  • Make sure that the Femur image shows the greater trochanter, the femoral neck, the femoral head and the ischium.
  • The entire femoral head must fit within the scan window or Total Hip BMD cannot be measured.
  • The femoral shaft should be straight and parallel to the edge of the scan image.
  • The greater trochanter should be centered vertically in the window.
  • 3-5cm of tissue (2-3 sweeps of the detector) must be visible above the greater trochanter and below the ischium.
  • A triangular foot restraint should be used to ensure that the leg has the proper 25 degrees of internal rotation.
  • A minimal amount of the Lesser Trochanter should be visible in the scans.

Acceptable AP Spine image

  • Make sure the spine is in the center of the image.
  • All of L4 must be shown.
  • The top of L5 should be shown in the first 1-2 sweeps of the detector.
  • Approximately 1/2 of T12 must be shown.
  • In the rare instance that a subject has 6 lumbar vertebrae, start counting from the bottom up. L5 is always between the iliac crests and L4 is the first one above it.
  • The extra vertebrae is normally located between L1 and T12 (the extra may even have floating ribs attached to it).

Acceptable Total Body image

  • A correct total body image includes the patient’s entire body.
  • Make sure the head, feet and arms are shown in the image.
  • Rotate the patient’s legs inward 25 degrees until the toes touch.
  • The patient’s arms should be at their sides, with the palms down, separated from the thighs, and within the scan limit border.
  • For patients who are too tall to fit on the table, the feet may be excluded from the scan.
  • If a patient is too wide to fit both arms in the scan, position the patient so ONLY part of their left arm is excluded from the scan.