Check the generator activity. Depending on local
circumstances decide if dual energy acquisition is acceptable or will there be too much
downscatter component.
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
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.
Position the patient for a posterior view using the Tc99m
window
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.
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
Start the acquisition a few seconds before
starting the generator flow and collect the dual images
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.
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.
