- Email: [email protected]
Production of carrier-free 18F-hydrofluoric acid
407
Technical notes TABLE 2. Activation data and results Irradiation time Neutron flux Sample Mass (mg) t 0SAgm activity (kBq) t tOAgm activity (kBq) t°TAg(n,~) l°SAgm o'(barn) t ogAg(n,y ) 1tOAgma(barn)
target material and by taking the ~t 0Agm production crosssection as 4.5 barn. TM This value of 0.32 barn, obtained from the initial activity ratio, is consistent with the value obtained from the measurement of activity, neutron flux and number of atoms. If the cross-section for the production of t°SAgm had been confirmed to be about 10 barn as once reported, I'° a specific activity of a curie (37 GBq) per gram of enriched target material could have been produced by irradiating the sample in a high flux reactor for a few months. Since the observed cross-section is only 0.33 barn, the expected activity is less by a factor of 30, diminishing the value of t°SAgm as a potential radionuclide for implant therapy.
1h (2.3 _+0.1) x 10 ta era- 2 s - t 1 10.125 0.26 ___0.04 11.9 _+ 1.0 0.35 _ 0.06 4.4 _+0.5
2 19.771 0.48 _ 0.07 23.9 _+2.1 0.31 _+0.06 4.5 _ 0.5
InternationalJournalof AppliedRadiationand Isotopes,Vol.29, pp. 407-408
© PergamonPressLtd. 1978.Printedin Great Britain 0020-708X/"/8/0601-0407$02.00/0 "
Production of Carrier-Free t 8F.Hydrofluori c Acid
Introduction
Acknowledgements--This work was supported by a Biomedical Research Grant to the New Jersey Medical School, Newark, New Jersey. The authors wish to thank Mr. H. HART and Mr. R. THOMPSON of Union Carbide Corporation, Tuxedo Park, New York, for their cooperation during this investigation, and Dr. N. E. HOLDEN of National Neutron Cross-Section Center at Brookhaven National Laboratory for useful discussions. DANDAMUDI V. RAO GEORGE F. GOVELITZ JOHN T. MALLAMS
Department of Radiology, New Jersey Medical School, College of Medicine and Dentistry of New Jersey, Newark, NJ 07103, U.S.A.
FLUORINE-18 (tSF) may be produced by a little-used nuclear reaction which occurs when neon is irradiated with 3He particles.ill The 1.5 sec half-life neon formed as follows: 2°Ne(3He, ct n) lSNe, decays by electron capture to give lSF, half-life 118 rain. To avoid adsorption of XSF on the target walls, an attempt was made to extract the XSNe and leave it to decay under conditions such that the 1s F generated is not absorbed. Moreover, by irradiating a neon-hydrogen mixture it should be possible to obtain H ~SF directly. M a t e r i a l and M e t h o d s
The target and the HtSF collection device are shown diagramatically in Fig. 1. The target holder is a nickel tube, Ni cke l t a r g e t
References 1. WAHLGREN M. A. and MEINKE W. W. Phys. Rev. 118, 181 (1960). 2. MUGHABGHAB S. F. and GARBER D. I. Neutron Cross Sections, Vol. 1, Resonance Parameters. Brookhaven National Laboratory Report. BNL-325 (1973). 3. HOLDEN N. E. and WALKERF. W. Chart of Nuclides, 10th edition. Knolls Atomic Power Laboratory (1968 ). 4. HOLDEN N. E. and WALKERF. W. Chart of Nuclides, 1lth edition. Knolls Atomic Power Laboratory (1972). 5. KISTNER O. C. and SUNYAR A. W. Phys. Rev. 143, 918 (1966). 6. LINDNER L., BRINKMANG. A. and SCHIMMELA. Nature, Lond. 240, 464 (1972). 7. HOLDEN N. E. National Neutron Cross Section Center, Brookhaven National Laboratory, Upton, New York (personal communication). 8. BERTRANDN. E., Nucl. Data Sheets B7, 33 (1972). 9. For the ICRU recommended SI units, see for example: WYCKOEF H. O., ALLISY A. and LIDEN K. Med. Phys. 3, 52 (1976). 10. ERDTMANG. and SovKA W. Die ~-linien der Radionuclide, Band 1. Kernfortschungsanlage Jiilich-1003-AC (1974). 11. RYEST. B. J. Nucl. Energy 25, 129 (1971).
!
[1
water
._._maoomete,
Monet valve
Neoncytinder ~
!
J i~,---T
u b e ( PT F E ]
FIG. 1. Circuit for the HtSF production.
40crn long and 5cm in dia, double-walled for cooling, closed on the particle inlet face by a 25 ~m-thick stainless steel foil. This tube is fitted with an inlet and an outlet tube which can be stopped by monel bellows valves. The valve at the back end of the tube is connected to a polytetrafluoroethylene (PTFE) spiral tube of length 2 m and dia 4-6ram. This spiral in which the tSNe is trapped can be
408
Technical notes
closed by two voltalef type fluorinated polymer valves. The other end of the PTFE tube is fitted to the target inlet through a flowmeter and a membrane compressor. A pump is provided to evacuate the system and the Ne + H2 mixture is introduced downstream from the PTFE trap. After evacuation of the circuit and the target ( > 10-2mm Hg) the gas mixture is fed in and the compressor started up. The irradiation is carried out with 27.5 MeV 3He particles and a 20-301aA current, the trap being immersed meanwhile in an alcohol-ice mixture at - 1 5 ° C (liquefaction temperature of H F = 19°C). At the end of irradiation the trap is shut off from the target and the trapped radioactivity recovered in a teflon tube at - 15°C placed at one end of the PTFE tube, while dichloromethane heated to 40°C is distilled through the other end. In this way about 70% of the radioactivity is recovered in 2-3 ml of solvent. The radioactivity may also be collected quantitatively with distilled water.
Results and Discussion For a 2 bar pressure of neon + 2% hydrogen mixture in the target and a 1.8m~/hr flow rate, the radioactivity collected in the PTFE tube amounts 1.6mCi/l.tA x hr
(E.O.B.). High pressure liquid chromatography, on a Partisil PS 10/25 SAX column in 0.1 M acetate buffer, of the aqueous solutions recovered gives the same Rf as an H F solution. Furthermore, if neon is irradiated without hydrogen,
considerably less radioactivity is trapped in the PTFE tube. These two tests appear to confirm the formation of H~aF under the working conditions described since if fluorine, which has a liquefaction temperature of - 188°C, is extracted from the target at the fast rate imposed by the compressor, it is not trapped at the operating temperature ( - 15°C). Under present conditions, the maximum quantity of HF obtainable is no more than 100-150mCi. However, the radioactivity variation of the H F collected as a function of the gas flow rate in the target shows that the yield can be increased appreciably by speeding up the flow. Although the yield is low, the preparation method described offers an easy means to obtain carrier-free HtaF. It could be suitable moreover for the manufacture of other fluorinated molecules such as N O ~8F. Direct labelling is also a possibility,~2) using the recoil energy which ~8F nuclei possess as they appear after decay of ~SNe. Commissariat &l'Energie Atomique, C. CROUZEL Dbpartment de Biolo#ie, D. COMAR
Service Hospitalier Frbdbric Joliot, 91400 Orsay, France
References 1. NOSAKI T., IWAMOTO M. and Ir)o T. Int. J. appl. Radiat. Isotopes 25, 393 (1974). 2. LAMBRECHT R. M. and WOLF A. P. in Radiopharmaceuticals (Edited by SUBRAMAN1Ar~ G., RHODES B. A., COOPER J. F. and SODD V. J.) pp. 111-124. Society of Nuclear Medicine, New York (1975).
Technical notes TABLE 2. Activation data and results Irradiation time Neutron flux Sample Mass (mg) t 0SAgm activity (kBq) t tOAgm activity (kBq) t°TAg(n,~) l°SAgm o'(barn) t ogAg(n,y ) 1tOAgma(barn)
target material and by taking the ~t 0Agm production crosssection as 4.5 barn. TM This value of 0.32 barn, obtained from the initial activity ratio, is consistent with the value obtained from the measurement of activity, neutron flux and number of atoms. If the cross-section for the production of t°SAgm had been confirmed to be about 10 barn as once reported, I'° a specific activity of a curie (37 GBq) per gram of enriched target material could have been produced by irradiating the sample in a high flux reactor for a few months. Since the observed cross-section is only 0.33 barn, the expected activity is less by a factor of 30, diminishing the value of t°SAgm as a potential radionuclide for implant therapy.
1h (2.3 _+0.1) x 10 ta era- 2 s - t 1 10.125 0.26 ___0.04 11.9 _+ 1.0 0.35 _ 0.06 4.4 _+0.5
2 19.771 0.48 _ 0.07 23.9 _+2.1 0.31 _+0.06 4.5 _ 0.5
InternationalJournalof AppliedRadiationand Isotopes,Vol.29, pp. 407-408
© PergamonPressLtd. 1978.Printedin Great Britain 0020-708X/"/8/0601-0407$02.00/0 "
Production of Carrier-Free t 8F.Hydrofluori c Acid
Introduction
Acknowledgements--This work was supported by a Biomedical Research Grant to the New Jersey Medical School, Newark, New Jersey. The authors wish to thank Mr. H. HART and Mr. R. THOMPSON of Union Carbide Corporation, Tuxedo Park, New York, for their cooperation during this investigation, and Dr. N. E. HOLDEN of National Neutron Cross-Section Center at Brookhaven National Laboratory for useful discussions. DANDAMUDI V. RAO GEORGE F. GOVELITZ JOHN T. MALLAMS
Department of Radiology, New Jersey Medical School, College of Medicine and Dentistry of New Jersey, Newark, NJ 07103, U.S.A.
FLUORINE-18 (tSF) may be produced by a little-used nuclear reaction which occurs when neon is irradiated with 3He particles.ill The 1.5 sec half-life neon formed as follows: 2°Ne(3He, ct n) lSNe, decays by electron capture to give lSF, half-life 118 rain. To avoid adsorption of XSF on the target walls, an attempt was made to extract the XSNe and leave it to decay under conditions such that the 1s F generated is not absorbed. Moreover, by irradiating a neon-hydrogen mixture it should be possible to obtain H ~SF directly. M a t e r i a l and M e t h o d s
The target and the HtSF collection device are shown diagramatically in Fig. 1. The target holder is a nickel tube, Ni cke l t a r g e t
References 1. WAHLGREN M. A. and MEINKE W. W. Phys. Rev. 118, 181 (1960). 2. MUGHABGHAB S. F. and GARBER D. I. Neutron Cross Sections, Vol. 1, Resonance Parameters. Brookhaven National Laboratory Report. BNL-325 (1973). 3. HOLDEN N. E. and WALKERF. W. Chart of Nuclides, 10th edition. Knolls Atomic Power Laboratory (1968 ). 4. HOLDEN N. E. and WALKERF. W. Chart of Nuclides, 1lth edition. Knolls Atomic Power Laboratory (1972). 5. KISTNER O. C. and SUNYAR A. W. Phys. Rev. 143, 918 (1966). 6. LINDNER L., BRINKMANG. A. and SCHIMMELA. Nature, Lond. 240, 464 (1972). 7. HOLDEN N. E. National Neutron Cross Section Center, Brookhaven National Laboratory, Upton, New York (personal communication). 8. BERTRANDN. E., Nucl. Data Sheets B7, 33 (1972). 9. For the ICRU recommended SI units, see for example: WYCKOEF H. O., ALLISY A. and LIDEN K. Med. Phys. 3, 52 (1976). 10. ERDTMANG. and SovKA W. Die ~-linien der Radionuclide, Band 1. Kernfortschungsanlage Jiilich-1003-AC (1974). 11. RYEST. B. J. Nucl. Energy 25, 129 (1971).
!
[1
water
._._maoomete,
Monet valve
Neoncytinder ~
!
J i~,---T
u b e ( PT F E ]
FIG. 1. Circuit for the HtSF production.
40crn long and 5cm in dia, double-walled for cooling, closed on the particle inlet face by a 25 ~m-thick stainless steel foil. This tube is fitted with an inlet and an outlet tube which can be stopped by monel bellows valves. The valve at the back end of the tube is connected to a polytetrafluoroethylene (PTFE) spiral tube of length 2 m and dia 4-6ram. This spiral in which the tSNe is trapped can be
408
Technical notes
closed by two voltalef type fluorinated polymer valves. The other end of the PTFE tube is fitted to the target inlet through a flowmeter and a membrane compressor. A pump is provided to evacuate the system and the Ne + H2 mixture is introduced downstream from the PTFE trap. After evacuation of the circuit and the target ( > 10-2mm Hg) the gas mixture is fed in and the compressor started up. The irradiation is carried out with 27.5 MeV 3He particles and a 20-301aA current, the trap being immersed meanwhile in an alcohol-ice mixture at - 1 5 ° C (liquefaction temperature of H F = 19°C). At the end of irradiation the trap is shut off from the target and the trapped radioactivity recovered in a teflon tube at - 15°C placed at one end of the PTFE tube, while dichloromethane heated to 40°C is distilled through the other end. In this way about 70% of the radioactivity is recovered in 2-3 ml of solvent. The radioactivity may also be collected quantitatively with distilled water.
Results and Discussion For a 2 bar pressure of neon + 2% hydrogen mixture in the target and a 1.8m~/hr flow rate, the radioactivity collected in the PTFE tube amounts 1.6mCi/l.tA x hr
(E.O.B.). High pressure liquid chromatography, on a Partisil PS 10/25 SAX column in 0.1 M acetate buffer, of the aqueous solutions recovered gives the same Rf as an H F solution. Furthermore, if neon is irradiated without hydrogen,
considerably less radioactivity is trapped in the PTFE tube. These two tests appear to confirm the formation of H~aF under the working conditions described since if fluorine, which has a liquefaction temperature of - 188°C, is extracted from the target at the fast rate imposed by the compressor, it is not trapped at the operating temperature ( - 15°C). Under present conditions, the maximum quantity of HF obtainable is no more than 100-150mCi. However, the radioactivity variation of the H F collected as a function of the gas flow rate in the target shows that the yield can be increased appreciably by speeding up the flow. Although the yield is low, the preparation method described offers an easy means to obtain carrier-free HtaF. It could be suitable moreover for the manufacture of other fluorinated molecules such as N O ~8F. Direct labelling is also a possibility,~2) using the recoil energy which ~8F nuclei possess as they appear after decay of ~SNe. Commissariat &l'Energie Atomique, C. CROUZEL Dbpartment de Biolo#ie, D. COMAR
Service Hospitalier Frbdbric Joliot, 91400 Orsay, France
References 1. NOSAKI T., IWAMOTO M. and Ir)o T. Int. J. appl. Radiat. Isotopes 25, 393 (1974). 2. LAMBRECHT R. M. and WOLF A. P. in Radiopharmaceuticals (Edited by SUBRAMAN1Ar~ G., RHODES B. A., COOPER J. F. and SODD V. J.) pp. 111-124. Society of Nuclear Medicine, New York (1975).