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I need help

Could someone help me with this pls..
I need to explain why 99m Tc is used over 123-iodine for investigating cerebral blood flow in brain scan. I have to include biological and radiological properties...
Thanks
Reply 1
Original post by Dani69
Could someone help me with this pls..
I need to explain why 99m Tc is used over 123-iodine for investigating cerebral blood flow in brain scan. I have to include biological and radiological properties...
Thanks

So you need to compare half-life, activity, and range of both those isotopes. A quick google will tell you, and then think about what the implications are- long short half life May mean most of it will have decayed before it gets administering or to organ where it’s needed. Poor range might mean it will not pass through enough tissue and thus not detectable out side the body by the detector. Think about if either is easily/naturally absorbed by the organ, might it need attaching to another compound- how easy is that? Is it a particularly delicate organ and would you then need for a short half life so that there is less exposure to the patient?
Reply 2
Original post by KimCW
So you need to compare half-life, activity, and range of both those isotopes. A quick google will tell you, and then think about what the implications are- long short half life May mean most of it will have decayed before it gets administering or to organ where it’s needed. Poor range might mean it will not pass through enough tissue and thus not detectable out side the body by the detector. Think about if either is easily/naturally absorbed by the organ, might it need attaching to another compound- how easy is that? Is it a particularly delicate organ and would you then need for a short half life so that there is less exposure to the patient?

Thank you so much and that was really helpful indeed.
Reply 3
Original post by KimCW
So you need to compare half-life, activity, and range of both those isotopes. A quick google will tell you, and then think about what the implications are- long short half life May mean most of it will have decayed before it gets administering or to organ where it’s needed. Poor range might mean it will not pass through enough tissue and thus not detectable out side the body by the detector. Think about if either is easily/naturally absorbed by the organ, might it need attaching to another compound- how easy is that? Is it a particularly delicate organ and would you then need for a short half life so that there is less exposure to the patient?

Hi Kim,
I did research quite a lot about those isotopes. In terms of the iodine because of the photon energy 154 keV and half-life of 13.22 hours -does it mean that patient will receive higher dose of radiation compared with 99m Tc where photon energy is 140keV? Is that one of the reason why 99m Tc is used for the brain scan?
Thanks

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