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Radiopharmaceutical Production
Radionuclide Transfer
Transfer Considerations
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RadionuclideTransfer
• Once the radionuclide is produced, it is necessary to get it from the cyclotron to the chemistry laboratory
• If the radionuclide is in the form of a gas, the transfer can usually be done with pressure and perhaps a push gas
• In the radionuclide is a liquid, it must either be pushed with pressure or transported in some type of container
• If the radionuclide is a solid, then there must be some transport container or system to move the target from the cyclotron vault to the laboratory for processing.
Contents• Gas transfer• Liquid transfer• Solid target transfer• Summary
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Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Gas Transfer
In the simplest scenario, the gas pressure in the target is used to push the gas to the hot laboratory.
An example of this operation is shown in the diagram at right. Click anywhere to start process. The valve out of the target will open and the target will empty into the vessel. The pressure will go to atmospheric
Pressure
Closed
750
ClosedOpen
15
Open
The transfer of gases is relatively easy in that the target gas can usually be moved with a pressure differential
Click again and the exit valve will close, the entrance valve will open and the target will pressurize.After that the process can be repeated until all the activity is out of the target.
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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C-11 transfer line - 60 meters
CH3I Synthesis Box
Transfer from the Cyclotron to the Chemistry Laboratory
Although the distance to the lab can be quite long, the transfer of gases is usually easy
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Liquid Transfer
• The transfer of liquids is slightly more problematic since the liquid can break up in to many tiny droplets and result in an inefficient transfer. The picture on the top at right shows the ideal situation where there is a single bolus.
• The picture below shows the water breaking up into small segments which increases the pressure required to transfer the liquid and decreases the efficiency of transfer.
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
STOP
Flow Patterns - Two Phase SystemThere several possible types of liquid and gas flow through a small bore line. These are shown in the diagram below along with the nomenclature.
As we go from pure gas flow, adding more and more liquid, we get these gradations in the type of flow through the tubing
Pure Gas Flow
Annular Flow
Annular-Wavy Flow
Slug Flow
Plug Flow
Bubble Flow
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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F-18 transfer line
Long distance F-18 Transfer
As an example, to transfer liquid over a 60 meter distance, it was impossible to reliably transfer pure water.
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Failure ModesMode 1 – Incomplete Transfer• The liquid is adhering to the walls of the tubing and the flow
becomes annular• Contamination of the surface will raise the surface tension of
plastic tubing and lower the surface tension of metal
Mode 2 – Line Plugging• Many small boli at the beginning of the liquid train is worse that
many small boli at the end of the train although the total force needed to push the liquid through should be the same
• This is probably due to compressibility of gas boli in the liquid train
The water had to be mixed with acetonitrile to reduce the surface tension and allow smooth transfer. The apparatus is shown on the next slide
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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F-18 Recovery Procedure
• Clean the station• Extract F-18 onto
resin with K2CO3 soln.
• Add MeCN to K2CO3 in mixing vessel
• Push through line to lab with He flow
• Rinse with pure MeCN
• The column never sees MeCN
O-18 from target
1 32
6 45
6 45
3 12
1 32
4 65
3 12
6 45
Helium in Vent
Plug
CO3--
Vent
O-18 recovery
MeCN rinse 2
MeCN rinse 1
Mixing
CleaningWater
CleaningWaterRecovery
ResinColumn
MeCN = acetonitrile
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
STOP
Transitions from one Flow pattern to another
• The surface tension dominated regime refers to plug, slug and bubbly flow
• The shear dominated regime refers to annular, mist and annular wavy flow
• The surface tension determines the type of flow which will occur in the tubing
Annular-Wavy Flow
Plug Flow
Low and high surface tension on a metal plate
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Ammonia Synthesis Using DeVarda’s Alloy
Water with [13N]Nitrates
DeVarda’s AlloyNaOH
Flow of Helium
Saline Solution
13NH3
Vent
Vacuum
SterilizingFilter
Another example of transfer of liquid is the production of N-13 ammonia using the DeVarda’s alloy method of converting nitrates into ammonia
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Solid Target Transfer
• There many target used to produce radionuclides which use a solid target. These targets can be internal targets which stay inside the cyclotron during the irradiation or they can be mounted externally on the cyclotron or on a beam line.
• After the irradiation, these targets must be moved to the hot cells for processing. This can be done pneumatically or with a train or other carrier
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Metal Target Systems
Beamline on “OSCAR” superconducting cyclotron
Solid target system for Siemens RDS 111 cyclotron
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Cu Targets
Beam
Cooling Gas
(He: -20C)
Target Holder
Targetry System
Collimator
Cooling Water
Irradiation PortCourtesy of Drs. Suzuki &
Fukumura, NIRS
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
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Solid Target Transfer
Solid target is loaded into target holder
After irradiation the target is dropped down a chute
At the end of the chute is a transport cart
The transport cart is then moved along a track to the hot cell for processing
Here is an example of a solid target transfer system where the target is moved using a cart and pulley system. It is mechanically very simple and therefore quite reliable
Radiopharmaceutical Production
Radionuclide Transfer
Contents
Gas transfer
Liquid transfer
Solid target transfer
Summary
STOP
Summary• The transfer of radionuclides from the cyclotron to the chemistry
lab can be quite simple or rather complex depending on the chemical and physical form of the target material.
• In gases, transfer is usually very simple with a pressure gradient being the driving force
• In liquids, the surface tension of the liquid and the distance over which the liquid must be transferred can be significant confounding factors in the transfer. Care must be taken to either keep the liquid from breaking up or to rinse the lines with a second bolus of liquid in order to transfer the maximum amount of activity.
• In solids, the targets are usually transferred using a mechanical system. The system may be as simple as a holder on a string, or as complex as a pneumatic transfer system with the ability to direct the target to several locations.
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