Dual Energy Acq




It is assumed that the standard QA checks have been carried out (daily flood, check on Tc99m and Kr81m windows, correct collimator etc) and a reservoir breathing system has been set up. In addition the issue of acceptable downscatter has been addressed.

Suggested Protocol
  1. Check the generator activity. Depending on local circumstances decide if dual energy acquisition is acceptable or will there be too much downscatter component.

  2. Inject the patient with Tc99m MAA , (up to 100MBq in UK). We recommend this is carried out with the patient in the same orientation as the imaging

  3. If the patient is anxious or elderly then it may help before the study to get the patient to take a few breaths through the facemask (without Kr81m) so that they are aware of how it feels.

  4. Position the patient for a posterior view using the Tc99m window

  5. Set up a dual acquisition count using 128x128 images. Depending on the activity of the generator and the camera stop conditions, determine the image time for 400k Kr81m counts and also 400k true Tc99m counts.

  6. Without moving the patient, get the patient to firmly hold the face mask for Kr81m and remind them to breath normally in and out through their mouth. Visually check that the reservoir tubing and mask are out of the field of view of the camera and switch to the Kr81m window on the camera

  7.   Start the acquisition a few seconds before starting the generator flow and collect the dual images

  8. If the generator is very active you may need to switch off the generator at a set time and continue counting to obtain sufficient Tc99m counts.

  9. repeat steps 3 -7 for left posterior oblique, right posterior oblique and anterior views. Ensure that the patient has sufficient rest from using the facemask during positioning in between each view.




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Last modified: November 29, 2002