155 Tb from radionuclide impurities for primary standardisation nuclear data measurements and SPECT imaging MEDICIS Promed Final Conference 30 April 4 May 2019 Erice Sicily ID: 801549
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Slide1
Extraction chromatography method for the separation of
155Tb from radionuclide impurities for primary standardisation, nuclear data measurements and SPECT imaging
MEDICIS-Promed Final Conference, 30 April – 4 May 2019, Erice, Sicily
Peter Ivanov
National Physical Laboratory, UK
Slide2Why terbium?161TbBeta/Auger therapySPECT diagnostics6.89 d
155TbSPECT diagnostics
5.32 d 152Tb
PET diagnostics
17.5 h
149
Tb
Alpha therapy
4.12 h
Decay Mode
Half-life
MRT Application
149
Tb
a
,
b+
(17%,
7%)
4.12 hours
Therapy
(
a
)
152
Tb
b
+ (17%)
17.5 hours
PET Imaging
155
Tb
EC (100%)
5.32 days
SPECT Imaging
161
Tb
b
- (100%)
6.89 days
Therapy (
b
-)
Slide3Production of 155Tb at CERN
Proton-induced spallation reactionTantalum target
On-line mass separation at 155 m/qIsotopes collected in a zinc-coated gold disc
Slide4Impurities139LaSTABLE155Gd
STABLE155
Eu4.75 aBeta- decay155
Dy
Electron Capture
9.9 h
139
Ce
Electron Capture
137.6 d
155
Tb
Electron Capture
5.3 d
Slide5Method developmentUsing stable element standards (159Tb, 140Ce)
ICP-MS analysisOxidation of ceriumChromatographic separation from HNO
3- Resin studies- Kinetic studiesColumn separation
=
(CPS)
0
= counts per second
before
contact with resin
(CPS)
t
= counts per second
after
contact with resin
V
= volume of HNO
3
(mL)
m
= mass of resin used (g)
Selective oxidation of cerium
:
Ce(III)
Ce(IV)
Tb(III) Tb(IV)
Slide6Ce(III) selective oxidationNaBrO3 oxidantCerium adsorption increasedSuggests that cerium is oxidised
Slide7Chromatography resin studiesStatic conditions, stable tracers24 h equilibrium timeTEVA, UTEVA and TK100 extraction resins
AG1-X8 anion exchange resin
Best separation using:UTEVA or TEVA
resin
High HNO
3
concentrations
TEVA
UTEVA
Slide8Elution profilesPre-packed 2 mL UTEVA cartridgeTerbium collected with 8 M HNO3Cerium eluted from column in 0.1 M HCl
Elution profile @ flow rate ~ 0.3 mL/min
Slide9Separation procedure
STEP 1
: Foil dissolutionSTEP 2: Removal of Tb and Ce from Au and Zn matrixSTEP 3: Isolation of Tb from CeSTEP 4: Conversion of Tb to chloride form
Slide10Active sampleNo 139Ce detected after separation
Supplied
155
Tb = ~ 8.1
MBq
Before
separation =
After
separation =
155Tb Primary standardisationSchematic of the NPL 4π(Liquid Scintillation)-γ(HPGe) Digital Coincidence Counting system Preliminary activity at the reference time (572.7 ± 2.9) kBq g-1 (k = 1)
A set of six sources measured For each the LSC channel efficiency varied by computer discrimination methodThe activity determined
by extrapolating to 100 % efficiency
Slide12155Tb Half-life measurementThe radioactive decay rate of 155Tb was observed over 18.6 days (or approximately 3.55 half-lives) using a HPGe γ-ray spectrometer. A total of 131 measurements were made.From each measurement the sum of the net peak areas of the 86.6 keV and 105.3 keV full-energy peaks was determined.
A non-linear weighted least squares fit was performed to the measured data points using the equation:
Slide13155Tb Half-life measurement Half-life of 155Tb determined in this work and the uncertainty budget Comparison of published half-life determinations of 155Tb
Slide14155Tb Emission probabilitiesThe normalised emission intensities of 89 emissions have been determined Standard uncertainties have been typically reduced by a factor of four [4] Reich, C. W., 2005. Nuclear data sheets for A = 155. Nuclear Data Sheets 104, 1-282.
Slide15155Tb SPECT ImagingDetails in Sophia Pells’ presentation Quantified nuclear medicine imaging of 155Tb siemens-healthineers.com
Slide16Column separation – Dy/Tb/Gd Stable elemental tracers & ICP-MS analysisLN resin Column volume ~8 mLFlow rate ~ 1 mL/min
(Semi-)Automated Lanthanide Separation
Slide17Highly efficient chemical separation method has been derived for removing the 139Ce impurity from the 155Tb (Submitted to Nature Scientific Reports)The world first primary standardisation of the potential theranostic SPECT radionuclide 155Tb has been performed at NPL which will provide traceability of the administered activities for any pre-clinical and clinical trials performed in the future.A precise half-life of 155Tb has been determined, which was found to have a 1.5 % relative difference to the current recommended value. A factor of 5 increase in the precision over previous measurements has been achieved.Precise measurements of the emission intensities of 89 -ray transitions have been performed. These make significant revisions to the currently recommended values with improved precision.
Conclusions
Slide18Acknowledgements
Chemical separation
Ben Webster (Surrey/NPL)ICP-MS analysis Ben Russell (NPL)
Active
Samples
Thierry
Stora,
Joao Pedro Ramos (CERN) Ulli Köster (ILL)Gamma Spectrometry
Sean Collins (NPL
)
Primary standardisation
Arzu
Arinc
, John Keightley (NPL)
SPECT Imaging
Andrew Robinson (NPL
)
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654002
Thank you for your attention! Questions?