ENDOCRINE SYSTEM

1-3-1 RADIOTRACERS

Elément Element	Production	Période Period	Energie Energy (keV)	Activité injectée Injected Activity	Dose absorbée/Activité utile Absorbed dose/Usable activity
Elément Element	Production	Période Period	Energie Energy (keV)	Activité injectée Injected Activity	Thyroïde Thyroid	Corps entier Whole body
Technétium Technetium 99m Tc04	Générateur Generator	6 h	Gamma =140	2 mCi 74 MBq	0,2 cGy 2 mSv	0,01 cGy 0,1 mSv
Iode 123 Iodine 123 123- I	Cyclotron (p, 5n)	13,2 h	EC X = 30 Gamma = 159	0,2 mCi 7,4 MBq	0,74 cGy 7,4 mSv	0,03 cGy 0,3 mSv
Iode 131 Iodine 131 131- I	Pile Nuclear reactor	8 j 8 d	E _beta= 250 X = 30 Gamma = 364	50 µCi 1,85 MBq	370 cGy 3 700mSv	0,04cGy 0,4 mSv

Technetium 99m : Diagnostic use.

Advantages : scanning 20 mn postinjection, very low radiation exposure, optimal availability.
Drawbacks : undergoes negligible organic binding, thus possible dissociation with iodine scans, salivary excretion.
Indications : routine scans, postsurgical residue, moderate iodine overload.
Iodine-123 : Diagnostic use .

Advantages : reference physiological tracer.
Drawbacks : scanning 2-4 h postinjection, average radiation exposure, limited availibility, high cost.
Indications : regular or further scans of isolated thyroid nodules, pediatrics.
Iodine-131 : Generally for therapeutic use, but also pretherapeutic uptake measurements and known cancers follow up.