This document summarizes a study characterizing long-lived metal impurities retained in FDG production cassettes at the Stanford Cyclotron and Radiochemistry Facility. Sixteen isotopes were identified in cassettes from 0.8 to 312 day half-lives. The trapping cartridge contained the most activity at 47.6%. Co-56 was the longest-lived isotope at 77.2 days, requiring 540 days of decay-in-storage per cassette. Future work could better determine radioactive versus non-radioactive cassette components to further reduce waste volumes in accordance with ALARA principles.

1. Characterization of Long-Lived Cyclotron Produced
Activation Metal Impurities Retained in FASTlab FDG
Cassettes during Synthesis of Radiolabeled 2-[18F] fluoro-2-
deoxy-D-glucose (FDG)
Presented at the 60th Annual Health Physics Society Meeting
Paul Swearingen, MHP
MOLECULAR IMAGING PROGRAM AT STANFORD
STANFORD HEALTH PHYSICS

2. Introduction
 PET radiopharmaceutical production on the rise
› Proportional increase in PET production sites worldwide
› Produced via Cyclotron
 Stanford Cyclotron and Radiochemistry Facility (CRF)
› F18 radiolabeled FDG production
› Supports clinical and research use
› Daily production
 Health Physics Functions
› Radioactive materials license
› Personnel monitoring
› ALARA
› Radioactive waste
Paul Swearingen, MHP

3. 3
Cyclotron and Radiochemistry Facility (CRF)
 16.5 MeV General Electric PETtrace
Cyclotron accelerator
› Protons/deuterons fired onto target
› Up to 6 targets
› Designed to produce common PET
radioisotopes
 Radiochemistry Systems
› Automated/Isolated
› Stand-alone process units for
specific radioisotopes
› Housed in lead shielded process
cabinet
Paul Swearingen, MHP

4. 4
FASTlab Synthesizer
 Automated radiochemistry system
› GE Heath Care Design
› converts externally produced
18F-fluoride/into [18F]-Tracer
 FDG production via individual
tracer cassettes
 Stanford uses FDG citrate
cassettes
Paul Swearingen, MHP

5. FDG Citrate Cassette
End Tubing
Eluent Vial
Alumina
Cartridge
Purification
Cartridge
Right Hand
6 ml Syringe
Trapping
Cartridge Reaction Vessel
Reagent Vials
Hydrolysis
Cartridge
Transfer Tubing
Left Hand 6 ml
Syringe
Paul Swearingen, MHP

6. Target Irradiation
 Charged particles accelerated and deflected onto target
› Enriched O-18 water target
› Secondary reactions in surrounding materials
› Proton/neutron activation in target and housing/shielding
 Activation metals leach into target water from surrounding materials
› Mainly from Havar Foils
• Co, Cr, Fe, Ni, Mn, W, Mo metals
› Cassettes retain activation metals
• Activity not uniformly distributed among components
Paul Swearingen, MHP

7. 7
Radioactive Waste
 Short-lived wastes
› F18 and other PET isotopes
› Decay-in-storage method (DIS)
 Long-lived wastes
› Target components
› FDG Cassettes
› Accumulation of waste
› Current disposal method vs.
DIS method
› Need to characterize
• Isotopes, activities, cassette
components
Paul Swearingen, MHP

8. Waste Characterization
 Unknown isotopes and activity amounts
› Gamma spectroscopy using HPGe
 Characterize isotopes in cassettes
› Determine half-lives and activities
› Determine required DIS time
 Determine radioactive components
› Distribution of isotope activities
› Reduce overall volume of waste
Paul Swearingen, MHP

9. Experiment Steps
 Collect cassettes from Cyclotron
› Coordinate with radiochemistry staff
› Separate components into 11 countable samples
› Collected total of 5 cassettes over 5 month period
› Random selection of cassettes
 Count samples using HPGe
› 12 hour counting time
› Repeatable geometry
› Background counts
› Acquire gamma ray spectra of each sample
› Collect activity and isotope data
 Data Analysis
› Determine distribution of isotopes/activities in each sample
› Determine required DIS times
Paul Swearingen, MHP

10. Paul Swearingen, MHP

11. Stanford HPGe Lab
 Ortec GMX Series Coaxial Detector System
› Model GMX20-70-CW
› N-Type Crystal
› Bias Voltage at 4000V
› DSPEC-jr. 2.0 MCA
› GammaVision v7.02 Software
 Energy and Efficiency Calibration
› Eckert & Ziegler Multi-gamma check source (AD-7066)
› 60 – 1836 KeV
 Lead shielded enclosure
› Low sample counts
› Important to minimize background
› 12 hr background spectrum before every run
Paul Swearingen, MHP

12. Isotope Composition at Irradiation
Co-56, 33.4%
Co-57, 0.9%
Co-58, 9.4%
Cr-51, 22.3%
Mn-52, 7.7%
Mn-54, 0.5%
Ni-57, 5.3%
Re-181, 1.7%
Re-182, 0.4%
Re-184, 0.4%
Tc-95, 5.7%
Tc-95m, 1.8%
Tc-96, 9.0%
V-48, 0.1%
Y-88, 1.2%
Zn-65, 0.3%
Zr-89, 0.1%
Paul Swearingen, MHP

13. Activity by Counting Sample
Right Hand 6 ml Syringe,
0.5%
Purification Cartridge,
0.9%
Alumina Cartridge, 6.7%
Transfer Tubing, 1.6%
Hydrolysis Cartridge,
5.0%
Reagent Vials Unit, 0.1%
Reaction Vessle, 8.9%
Left Hand 6 ml
Syringe, 13.0%
Trapping
Cartridge,
47.6%
Eluent Vial + 1 ml
Syringe, 11.9%
End Tubing, 3.6%
Paul Swearingen, MHP

14. 14 10 CFR PART 30 —RULES OF GENERAL
APPLICABILITY TO DOMESTIC
LICENSING OF BYPRODUCT MATERIAL
Exemption Limits
 § 30.70 Schedule A--Exempt
concentrations
› Specific activity limits for
various isotopes
› For multiple isotopes,
combined ratio must not
exceed unity
Isotope Concentration [μCi/mg]
Cd-109 2.00E-03
Co-56 1.00E-06
Co-57 5.00E-03
Co-58 1.00E-03
Cr-51 2.00E-02
Mn-52 3.00E-04
Mn-54 1.00E+00
Ni-57 1.00E-03
Re-182 1.00E-06
Re-183 6.00E-03
Re-184 1.00E-06
Re-186 9.00E-04
Tc-95m 1.00E-06
Tc-96 1.00E-03
V-48 3.00E-04
W-181 1.00E-06
Y-88 1.00E-06
Zn-65 1.00E-03
Paul Swearingen, MHP

15. Summary of Results
 16 isotopes in 5 cassettes
› 0.8 – 312 day half-lives
› 122 – 1434 KeV gammas
› 0.01 – 1.2 uCi activities
 Stanford “Decay-in-Storage” (DIS) policy
› Per our license with State of California
› DIS for 7 half-lives, if half-life less than 120 d
 All but 2 components are non-exempt
› Co-56/Tc-95m
› 77.2 and 62 day half-lives
Paul Swearingen, MHP

16. Conclusions
 Co-56 is the longest lived, non-exempt isotope
› 77.2 day half life
› 540 day DIS time per cassette
› After DIS  dispose as non-radioactive waste
 DIS of entire cassette better option
 All but 2 components considered non-radioactive
› ≈22% volume reduction
 Insufficient statistics to verify radioactive vs. non-radioactive components
› Small sample size (n = 5)
 Time, Distance, Shielding
› Dose considerations working directly with cassettes
Paul Swearingen, MHP

17. Future Considerations
 Develop Standard Operating Procedure for DIS and handling of Cassettes
 Institute routine waste pick-up policy for wastes containing activated
metals
› Daily throughput  estimate of 30 cassettes/month
 Further analysis
› More Cassettes, better statistics  determine radioactive vs. non-
radioactive components with greater degree of certainty
› Relationship between cyclotron irradiation conditions and isotope
composition
› Cost-benefit analysis
 ALARA considerations
› Dose to worker estimates
› Shielding
Paul Swearingen, MHP

18. Acknowledgements
Dawn Banghart, CHP Stanford Health Physics
Lance Phillips, CHP Stanford Health Physics
Don Samaan, NRRPT Stanford Health Physics
Marshall Wen Stanford Health Physics
Fred T. Chin, PhD Assistant Professor (Research), Assistant Professor
(Research), Radiology- Molecular Imaging Program at
Stanford
Bin Shen, PhD Radiochemistry Senior Research
Associate
George Montoya Cyclotron Production Technician
Paul Swearingen, MHP

19. Questions?
Paul Swearingen, MHP

20. References
Ferguson, D. et al., “Measurement of long lived radioactive impurities retained in the
disposable cassettes on the Tracerlab MX system during the production of
F18[FDG]”, Appl. Radiat. Isotopes (2011)
O’Donnell, R.G., “Measurement of the residual radioactivity induced in the front foil
of a target assembly in a modern medical cyclotron”, Appl. Radiat. Isotopes (2003)
LNHB Recommended Data. LNHB, 21 May 2015. Web. 15 June 2015.
<http://www.nucleide.org/DDEP_WG/DDEPdata.htm>.
Radionuclide Transofrmations: Energy and Intensity of Emissions. ICRP Publication
38 ed. Vol. 11-13. Oxford: Pergamon, 1983. Print.
PETtrace Reference Manual. Milwuakee: GE Medical Systems, 1998. Print.
FASTlab FDG Citrate Application Manual. Waukesha: GE Healthcare. Print.
Paul Swearingen, MHP