Radiochemical determination of cross sections of α-particle induced reactions on 192Os for the production of the therapeutic radionuclide 193mPt

doi:10.1016/j.apradiso.2010.05.002

Applied Radiation and Isotopes

Volume 68, Issue 10, October 2010, Pages 2001-2006

https://doi.org/10.1016/j.apradiso.2010.05.002 Get rights and content

Abstract

For determination of cross sections of α-particle induced reactions on 99.65% enriched ¹⁹²Os, the methods for electrolytic preparation of thin samples and radiochemical separation of radioplatinum were optimized. The excitation functions of the ¹⁹²Os(α,n)^195mPt and ¹⁹²Os(α,3n) ^193mPt reactions were measured from 20 to 39 MeV. The cross section of the latter reaction reaches a maximum value of about 1.5 b at an energy around 36 MeV. The results of nuclear model calculations using the codes TALYS and STAPRE agreed well with the measured data. The optimum energy range for the production of no-carrier-added ^193mPt (T_1/2=4.33 d) was found to be E_α=40→30 MeV. The thick target yield amounts to 10 MBq/μA h and a possible batch yield of 2 GBq should be sufficient for Auger electron therapy on a wide scale.

Introduction

In recent years, low-energy electron emitters have been gaining considerable significance in internal radiotherapy (cf. Mariani et al., 2000). One such radionuclide is ^193mPt (T_1/2=4.33 d). It is a high spin isomer, decaying by highly converted isomeric transition, and emits about 26 Auger electrons per decay (Azure et al., 1992), in comparison to 21 electrons for ¹²⁵I, 11 electrons for ¹²³I, and 8 electrons for ¹¹¹In (Mariani et al., 2000). The radionuclides ¹²⁵I and ¹¹¹In are presently commonly used in Auger electron therapy while ¹²³I is being considered for this use. The radionuclide ^193mPt is of great potential interest not only because of its suitable decay properties but also because platinum-complexes (like cis-platin and others) are used in chemotherapy as potent antitumor agents. The administration of cis-dichloradiamineplatinum (cis-DDP) labeled with ^193mPt or the other Auger electron emitter ^195mPt (T_1/2=4.03 d; 33 Auger electrons) (Lange et al., 1973, Tóth, 1980) may contribute to therapeutic management by providing information on the distribution and localization of cis-DDP. However, to make the internal radiotherapy effective, it is necessary to use one of these radionuclides in the same chemical complex with high specific activity. The difficulty arising when one intends to produce either of these radioplatinum isotopes with sufficiently high specific activity by reactor irradiation is the low neutron cross section of ¹⁹⁴Pt and/or the low abundance of ¹⁹²Pt.

In a recent attempt to produce both ^195mPt and ^193mPt with high specific activity, Hilgers et al. (2008) investigated the ¹⁹²Os(α,n)^195mPt and ¹⁹²Os(α,3n)^193mPt reactions up to 27 MeV using 85% enriched ¹⁹²Os as target material. The cross section of the (α,n) reaction was found to be extremely low. Thus the expected yield of ^195mPt is very low. On the other hand, the (α,3n) reaction showed a high cross section even at 27 MeV. It could be predicted that its cross section at about 35 MeV would be much higher, so that this reaction could possibly be employed for large scale production of no-carrier-added ^193mPt.

The present work deals with the measurement of cross sections of α-particle induced reactions on 99.65% enriched ¹⁹²Os in the energy range of 20–40 MeV. Considerable effort was devoted to optimization of dissolution of enriched material, electrolytic preparation of thin target samples, and chemical separation of the desired reaction products from the matrix activity.

The radioactivity of ^193mPt can be determined precisely only via X-ray spectrometry, a rather subtle technique which demands extreme care and clean radiochemistry. The experimental data are both of fundamental and applied interest. A comparison of the experimentally determined data with the theoretical values obtained using nuclear model calculations throws light on the reliability of model calculations. It may be mentioned that the model calculations on the formation of high-spin isomeric states, like ^193mPt, are very challenging. The main aim of the study was, however, to determine the optimum conditions for the production of ^193mPt with high radionuclidic purity.

Section snippets

Preparation of thin targets

For cross section measurements, thin films of osmium on a suitable backing were needed. It is very difficult to obtain a thin film of osmium by evaporation in an ordinary apparatus because of its high melting point (about 3000 °C). The common method to prepare an osmium target is to convert the metal via OsO₄ into potassium perosmate and then carry out the electrodeposition.

Nuclear model calculations

In order to check the consistency in the experimental data and possibly to validate those data, nuclear model calculations were performed using two codes. Special care regarding the choice of the input parameters was necessary since the isomeric states are rather difficult to describe.

¹⁹²Os(α,n)^195mPt reaction

The radionuclide ^195mPt (T_1/2=4.03 d, spin 13/2⁺) decays by IT (100%) to the ground state, which is stable. The activity of the radiochemically separated nuclide was determined using the γ-ray at 98.85 keV. The measured cross sections are given in Table 3, and are graphically shown in Fig. 2 together with the only existing data set by Hilgers et al. (2008) who reported values up to the alpha particle energy of 27.5 MeV. Our data cover the energy range from 20.5 to 39 MeV and the observed cross

Conclusion

New cross sections for the production of the radionuclides ^193mPt and ^195mPt via α-particle induced reactions on enriched ¹⁹²Os were obtained up to 39 MeV. The optimum energy range for the production of ^193mPt was found to E_α=40→30 MeV. In this energy range the unavoidable co-produced ^195mPt impurity is 0.6%. The results provide basic information on the production of no-carrier-added ^193mPt in quantities sufficient for therapeutic applications.

Acknowledgements

The authors thank the operation crew of the CGR-560 cyclotron of the Vrije Universiteit Brussel (VUB), Brussels, Belgium, for their help in performing the irradiations. We thank S. Spellerberg for help in carrying out the experiments. M.S. Uddin specially thanks the Alexander von Humboldt Foundation for financial support to conduct this research work in Germany, and the Bangladesh Atomic Energy Commission for granting him leave of absence.

References (34)

N. Ahmed et al.
The liquid-liquid extraction of platinum in the presence of tin(II) chloride from dilute hydrochloric acid into 4-methyl-2-pentanone
Anal. Chim. Acta
(1984)
R. Arakawa et al.
Electroplating of osmium
Nucl. Instrum. Methods
(1975)
D.M. Brink
Individual particle and collective aspects of the nuclear photoeffect
Nucl. Phys.
(1957)
W. Boeglin et al.
Electroplating of thick osmium targets
Nucl. Instrum. Methods Phys. Res. A
(1986)
A. Cecchi
The preparation of osmium targets by electroplating
Nucl. Instrum. Methods Phys. Res. A
(1991)
S. Chakrabarty et al.
Preparation of thin osmium targets by electrodeposition
Nucl. Instrum. Methods Phy. Res. B
(2001)
K. Hilgers et al.
Production of the therapeutic radionuclides ^193mPt and ^195mPt with high specific activity via α-particle-induced reactions on ¹⁹²Os
Appl. Radiat. Isot.
(2008)
A.J. Koning et al.
Local and global nucleon optical models from 1 to 200 MeV
Nucl. Phys. A
(2003)
L. McFadden et al.
Optical-model analysis of the scattering of 24.7 MeV alpha particles
Nucl. Phys.
(1966)
A.E. Stuchbery
Electrodeposition of Pt and Os targets for nuclear reaction experiments
Nucl. Instrum. Methods
(1983)

G. Tóth

A novel target for reactor-produced ^193mPt

Int. J. Appl. Radiat. Isot.

(1980)

D. Wilmore et al.

The calculation of neutron cross-sections from optical potentials

Nucl. Phys.

(1964)

P. Axel

Electric dipole ground-state transition width strength function and 7-MeV photon interactions

Phys. Rev.

(1962)

Azure, M.T., Sastry, K.S.R., Archer, R.D., Howell, R.W., Rao, D.V., 1992. Micorscale synthesis of carboplatin labelled...

Bersillon, O., 1981. SCAT 2: un programme de modele optique spherique. Centre d´Etudes de Bruyéres-le-Châtel Report,...

Belgya, T., Bersillon, O.,Capote, R., Fukahori, T., Zhigang, G., Goriely, S., Herman, M., Ignatyuk, A.V., Kailas, S.,...

M. Bonardi et al.

Cyclotron production, radiochemical separation and quality control of platinum radiotracers for toxicological studies

J. Radioanal. Nucl. Chem.

(1998)

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¹: Guest scientist from Institute of Nuclear Science and Technology, Atomic Energy Research Establishment, GPO Box 3787, Dhaka-1000, Bangladesh.

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Radiochemical determination of cross sections of α-particle induced reactions on 192Os for the production of the therapeutic radionuclide 193mPt

Abstract

Introduction

Section snippets

Preparation of thin targets

Nuclear model calculations

192Os(α,n)195mPt reaction

Conclusion

Acknowledgements

Anal. Chim. Acta

Nucl. Instrum. Methods

Nucl. Phys.

Nucl. Instrum. Methods Phys. Res. A

Nucl. Instrum. Methods Phys. Res. A

Nucl. Instrum. Methods Phy. Res. B

Appl. Radiat. Isot.

Nucl. Phys. A

Nucl. Phys.

Nucl. Instrum. Methods

Int. J. Appl. Radiat. Isot.

Nucl. Phys.

Electric dipole ground-state transition width strength function and 7-MeV photon interactions

Phys. Rev.

Cyclotron production, radiochemical separation and quality control of platinum radiotracers for toxicological studies

J. Radioanal. Nucl. Chem.

Radiochemical determination of cross sections of α-particle induced reactions on ¹⁹²Os for the production of the therapeutic radionuclide ^193mPt

¹⁹²Os(α,n)^195mPt reaction