Derivation of the Lung TAC

The TAC of the lungs provides a reasonable approximation of the shape of the blood curve. It is obtained in a lung VOI which must been outlined in transmission images, because there is not poor anatomical information in the water images. It is essential that the dynamic H₂¹⁵O-PET images and the transmission images are exactly aligned.

Please perform the following steps which are illustrated above.

• Using the Load Input button load both the dynamic emission images and the matching transmission images .
  
• After the images have been loaded, select the VOI button. In the appearing VOI construction dialog make sure to switch to the transmission images and draw regions in the left and right lung.
  
  Close the VOI dialog with the Ok button.
• As a result, the emission TACs in the left and right lungs are calculated, averaged and displayed in the curve area (see illustration above).

Notes:
1. It is important that the acquisition times of the dynamic images are correct.
2. If the acquisition has been performed using a hybrid PET/CT scanner it should be possible to use the CT images for defining the Lung VOIs, because PMOD relates the VOI to the scan landmark which is normally identical in both scans.

If the lung TAC is already available as a file the loading of the transmission data and the VOI outlining is not necessary. In this case it is sufficient to load the dynamic H₂¹⁵O-PET images, then load the lung TAC with one of the buttons Load Lung TAC or Load Lung TAC from DB, Then the FA can immediately be started.