[Gate-users] Positron range of Y-90

Paulo Caribé Paulo.Caribe at UGent.be
Mon Dec 10 15:38:02 CET 2018

Hi everyone,

I have a question about positron range of Y-90.  I’ve been trying to simulate the PET/MR using Yttrium-90 as a radioactive source (I've used the fastY90 source in Gate 8.0 for this)
So, the decay scheme for Y-90 has a very small branching ration (32ppm) that emits an electron-positron pair via internal pair conversion (0+/0+ transition) from the transition at 1.76 MeV (figure in the attachment). I am wondering about which value could be the energy of the positron... considering that both have the same mass, is that wrong consider the energy of the positron to be half of this energy (1.76MeV)?

(fastY90)       Equation
        E = 1.76 MeV    E = 0.88 MeV
Soft Tissue     0.95    2.06    0.93

The results in Gate fastY90 results seem to be according to the smaller energy but I wonder if the positron range should be around 2mm as the 1.76 MeV results suggest.

Any thoughts on what might be happening?


Paulo Caribé

Doctoral researcher
Ghent University & KU Leuven - CNPq
Medical Imaging and Signal Processing (MEDISIP)
IBiTech - Campus UZ - C. Heymanlaan 10, (Block B/5)
Entrance 36  - 9000 Gent, Belgium

Tel: +32 9 332 43 22
email: Paulo.Caribe at ugent.be<mailto:StijnD.Bonte at ugent.be>

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