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124Iodine Production & 125Tellurium
Target
Suliman J. Al-Yanbawi
Section Head, RPP
KING FAISAL SPECIALIST HOSPITAL AND RESEARCH CENTRE
Cyclotron & Radiopharmaceuticals Production

Topics:
 124Iodine.
 Decay Scheme.
 Data for 124Iodine Production.
 125Tellurium Target.
 Data For 124Iodine Production @ KFSH & RC.
 125Tellurium Target Development.
 125Tellurium Metal & Oxide Photo.
 Preparation of 125Tellurium Plating Solution.
 125 Tellurium Plating System.

Introduction
Sodium Iodide(I-124) has half-life of 4.176 days, and becoming
an important useful Radio-tracer for PET imaging, and dosimetry.
124I-Iodine has long half-life of 4.176 days and emission 23% Beta.
The longer half-life adding an advantage for Radiopharmaceutical
and pharmacokinetics analysis.

124Iodine Decay Scheme.
Iodine(I-124) half 4.176 d and has (6)six positron transitions , more than
(75) seventy five gamma transitions, and (25) twenty five electron capture
transition.
ANNALS OF ICRP PUBLICATION # 38

● 124Iodine can be produced with different forms of nuclear reactions
. listed below in Table A.
Nuclear reaction Target
material
Energy
Range Mev
Enrichment
Of Te-%
Impurities Yield Ref.
124Te (p,n) 124 I
5 % Al2O3
TeO2 11.6→ 0 99.8 I-123 6.88 MBq/uAhrs
0.186 mCi/uAhrs
1
124Te (p,n) 124 I TeO2 12.6 99.8 I-123 13.0 MBq/uAhrs
0.351 mCi/uAhrs
2
124Te (p,n) 124 I Al2 Te3 11.→ 2.5 99.5 I-125
I-126 <0.001%
0.229mCi/uAhrs 3
124Te (p,n) 124 I
5 % Al2O3
TeO2 14.→ 7.0 99.86 I-125 → 0.03%
I-126 →0.007%
0.570mCi/uAhrs 4
124Te (d,2n) 124 I Te(metal) 14.→ 10 99.8 I-125 →1.7% 0.473mCi/uAhrs 5
125Te(p,2n) 124I Te(metal) 21.→ 15 99.9 I-123 → 7.4%
I-125 →0.9%
2.19mCi/uAhrs 5
Data For Production of 124Iodine Table – A :

124Iodine Production:
○ Production of 124 Iodine with the high yield depends on the listed factors :
1- The enrichment of 125Tellurium → more than 99.0 %.
2- 125Tellurium target electroplating plating quality, and stability during
irradiation ( Tellurium thermal conductivity is 1.97 Kw/ m 0k).
3- 125Tellurium thickness mg/cm2 → ( 12 to 22 ).
4- Energies of proton range(18Mev→ 20Mev) is the optimum for production
124Iodine. The 124I is more than 98.0% & the contaminant are less than 1.0%
for (121I, 123I, 126I, & 130I).
5- Coolant temperature and heat transfer efficiency during irradiation,
(flow rate = ∆Q / ∆T (Jules/Second))that affect on the Tellurium target,
stability and Iodine production Yield (mCi/uAhrs).
○ The 124Iodine separated from 125Tellurium target as sodium Iodide;
Needs fast efficient reliable chemical processing procedure; The
Recovery of 124Iodine is more than 80 %; and the radiochemical yield
is more than 95% at end of processing as a sodium iodide ( I - , iodide).

The advantage of using 125Tellurium:
1- There are several possibility of nuclear reaction for producing 124Iodine;
the excitation function of 125Te (p,2n) 124I reaction is the best and it’s production
rate is very high comparing to other nuclear reactions Yield (mCi/uA-hrs).
2- Radionuclides of 124Iodine availability (abundance) is more than 98.0% and other
contaminant are less than 1.0% of (121I,123I, 126 I, & 130I)
at end of irradiation (EOB), see Table-B.

Data For 124Iodine Production
@KFSH & RC
Irradiated 125Te (p,2n) 124I Target(s) ; TABLE-B

Target Development for I-124 Production:
The radio-chemistry section staff of RPP Developed and optimized technical methodology
for electrochemically depositing Tellurium on the copper back-plate
(coated with the nickel). The copper plate can stand and able of dissipating
more than 7.5 Kw thermal conductivity.
The Tellurium metal converted into Tellurium oxide and must be in one
of the following chemical form or booth:
a: β – TeO2 yellow orthorhombic crystal or
b: α – TeO2 colorless tetragonal crystal.
By Dehydration of telluric acid ( H2 TeO2 ) or tellurium nitrate ( TeO4 – HNO3 )
above 400oC.
Note: The two chemical forms of Tellurium dioxide are important for improved characteristic as :
1- Tellurium electroplating deposition stability and quality of surface
smoothness & homogeneity.
2- Tellurium adhesion stability during irradiation ( stable@ 1.3 Kw tested ).

Tellurium Metal and Tellurium Dioxide :
 α - TeO2 Colorless Tetragonal Crystal.
 β – TeO2 Yellow Orthorhombic Crystal.
 Tellurium Metal Chunks.
 Enrichment is more than 99.0%
Tellurium
Tellurium Crystals
TeO2
Crystals
TeO2 Crystals

Preparation Of 125Tellurium Plating Solution:
 Plating solution is prepared by dissolving Tellurium
dioxide (equivalent of 16mg/ml, Te-metal) in a hot
solution of potassium hydroxide (KOH- 10mg/ml),
the final volume of plating solution is made 250ml
ready for plating.
 The solution is poured in the plating vessel with
(4) four target plates at the same time.
The(- Ve)connected to the plates & (+ve)
connected to platinum electrode.
 At the end of plating place the plated targets in the
oven for drying at 160 oC for one hour. Then
targets are ready for irradiation.
 The optimum Tellurium target thickness must be
must in the range : 12 mg/Cm2 to 22 mg/cm2 .
STIRRER
TARGET PLATE
MOTOR
CLAMP RING
PLATING VESSEL
PLATING SYSTEM

125TELLURIUM PLATING SYSTEM
PLATED
TELLURIUM Copper Plate
Coated with
Nickel
Power Supply
Stirrer
Motor
Ammeter
Target
Plating Vessel
Clamp

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