I do not have experience working with PET scanners for patients so I don't know if the software automatically corrects for the branching ratio of the nuclide. Most of the conventional nuclides have positron branching ratios close to 100% (18F, 11C, 68Ga) so the branching ratio does not affect the computation significantly. However, since the positron branching ratio of 64Cu is 17.6%, 5.5 mCi of 64Cu emit the same amount of 511 keV gammas as 1 mCi of 18F and in this case the computation could be off by a factor of 17.6/96.7 = 0.18. For instance if a subject is injected with 5.5 mCi of 64Cu and a lesion captures 100 %ID, the software could potentially assume that the lesion captured only 1 mCi (assuming it is 18F) and since the injected activity is 5.5 mCi 64Cu the software could assume that the %ID was 18% instead of 100%. I ask this because it seems to me that the SUV values for 64Cu and 89Zr reported in the literature are low, as if the positron branching ratio is not being considered.
The PET in my centre allows that branching ratio can be defined for each isotope. So, the conversion of counts on activity concentration, and therefore SUV, is always correct (if the branching ratio is correct).
You may need to use a new calibration factor between counts and bq for Cu which may be different than 18F.
PET scanners in our centre (GE Discovery 710, Siemens mMR) will correct for the positron branching ratio. When you select the isotope, the overall calibration factor of the scanner is adjusted by the branching ratio. Older scanners might not have these presets, but you could verify this for yourself on your system if you scan a phantom with a known activity concentration and see what you get in the images.
Usually and this is the case for many manufacturer. The isotope chosen from the acquisition tab will then use the branching ratio for correction. Having said that it is Always good to check with the manufacturer of your scanner
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