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The study of proton beam irradiated H218O water target
Nuclear Instruments and Methods in Physics Research B 241 (2005) 735–737 www.elsevier.com/locate/nimb
The study of proton beam irradiated H218O water target Min-Goo Hur a
a,*
, In-Su Jung a, Hong-Suk Chang a, Seung-Dae Yang a, Jong-Seo Chai a, Hwan-Sup Oh b
Korea Institute of Radiological and Medical Sciences, 215-4, Gongneung-dong, Nowon-gu, Seoul 139-740, Republic of Korea b KyungHee University, Sechen-ri, Giheung-eup, Yongin, Gyunggi-do 449-701, Republic of Korea Available online 31 August 2005
Abstract The aim of this research is to observe phenomena inside of a H218O water target during the proton beam irradiation. We made a target unit which enabled to visualize and tested it by using a 30 MeV proton beam from a cyclotron at KIRAMS. In the case of a closed target system, we found that the bubbles inside of the target become smaller and dispersed over the volume as the beam intensity increases and the pressure on the water becomes higher. As a result of this study, it turned out that the target can absorb the initial proton energy completely and there arises no need to have an additional energy degradation length. It has been also found that the target has a saturation point of the irradiation current to the liquid phase due to bulging of the target windows. Consequently, RI production yield in the target depends on this value. For designing a high yield water target, suppression of the target windows and improvement of the cooling efficiency are required. Ó 2005 Elsevier B.V. All rights reserved. PACS: 87.58.Fg Keywords: FDG; RI (radioisotope); Water target; Cyclotron; PET
1. Introduction F-18 is produced by 18O(p, n)18F nuclear reaction followed by a radiofluorination to give [18F]FDG [1]. For increasing the F-18 production yield, many scientists have made a research on the water target
[2,3]. Mainly there are two way; one is cooling efficiency increase and other is increasing irradiation currents. In this study, the variation of water target inside was observed when the proton beam irradiated to find a optimize operation condition. 2. Method
*
Corresponding author. Tel.: +82 2 970 1335; fax: +82 2 970 1332. E-mail address: [email protected] (M.-G. Hur).
The test target was assembled like Fig. 1. The target and front window foil was made by
0168-583X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2005.07.173
736
M.-G. Hur et al. / Nucl. Instr. and Meth. in Phys. Res. B 241 (2005) 735–737
Fig. 1. Schematic drawing for test target.
titanium. For observation of target inside, back window was made by quartz and Panasonic GP-KS162HD CCD camera was installed to monitor this. The experimental conditions are like this: (1) proton beam current: 1–23 lA, increment 1 lA in one additional minute, (2) cooling: one side water cooling, flow late 5 L/min at 23 °C, (3) target has sealed by Swagelok SS42 valve.
3. Results 3.1. Pressure and bubble float
Fig. 3. Bubble floats during proton beam irradiation (0.25 s interval).
tured figure of bubble float is shown in Fig. 3. In closed target system experiments during bombardment, circulation of gas phase looks like bubble which has been presented at the top of target cavity was observed. The bubbles are scattered followed by causing pressure rising with current increasing. As a result of this, it turned out that the target can absorb the initial proton energy completely and there arises no need to have an additional energy degradation length.
The correlation between irradiation current, pressure and temperature is shown in Fig. 2. In this figure, the graph can be divided into three areas; first is over cooling area, second is heating area and third is over heating area. If given more cooling, the heating area will be expanded and make high current irradiation possible. The cap-
3.2. Gas phase and target deformation
Fig. 2. Behavior of pressure and temperature versus irradiation current.
Fig. 4. Behavior of gas phase ratio versus irradiation current to H218O.
Fig. 4 is a graphical view of gas phase increasing. The growth of gas phase is increasing the deformation of window foil. The grown gas phase ironically has made lower the area where the proton beam irradiated. That cause of accelerating
M.-G. Hur et al. / Nucl. Instr. and Meth. in Phys. Res. B 241 (2005) 735–737
737
pressure rising against that reduces cooling area. For more safety operation, target should be restrained by the pressure with high cooling and wide heat transfer area or mechanically restricted the deformation of window foil.
sequently, RI production yield of F-18 water target can be predicted depending on this saturate value. For designing a high yield water target, suppression of the target windows and improvement of the cooling efficiency are required.
4. Conclusion
References
In conclusion, the target has three modes when proton beam irradiated. In over heating area, it has been found that the target has a saturation point against the irradiation current to the liquid phase due to bulging of the target windows. Con-
[1] G. Stocklin, V.W. Pike, Radiopharmaceuticals for Positron Emission Tomography, Kluwer Academic Publishers, 1993. [2] S.-J. Heselius, D.J. Schlyer, A.P. Wolf, Appl. Radiat. Isot. 40 (1989) 663. [3] E. Hess, G. Blessing, H.H. Coenen, S.M. Qaim, Appl. Radiat. Isot. 52 (2000) 1431.
The study of proton beam irradiated H218O water target Min-Goo Hur a
a,*
, In-Su Jung a, Hong-Suk Chang a, Seung-Dae Yang a, Jong-Seo Chai a, Hwan-Sup Oh b
Korea Institute of Radiological and Medical Sciences, 215-4, Gongneung-dong, Nowon-gu, Seoul 139-740, Republic of Korea b KyungHee University, Sechen-ri, Giheung-eup, Yongin, Gyunggi-do 449-701, Republic of Korea Available online 31 August 2005
Abstract The aim of this research is to observe phenomena inside of a H218O water target during the proton beam irradiation. We made a target unit which enabled to visualize and tested it by using a 30 MeV proton beam from a cyclotron at KIRAMS. In the case of a closed target system, we found that the bubbles inside of the target become smaller and dispersed over the volume as the beam intensity increases and the pressure on the water becomes higher. As a result of this study, it turned out that the target can absorb the initial proton energy completely and there arises no need to have an additional energy degradation length. It has been also found that the target has a saturation point of the irradiation current to the liquid phase due to bulging of the target windows. Consequently, RI production yield in the target depends on this value. For designing a high yield water target, suppression of the target windows and improvement of the cooling efficiency are required. Ó 2005 Elsevier B.V. All rights reserved. PACS: 87.58.Fg Keywords: FDG; RI (radioisotope); Water target; Cyclotron; PET
1. Introduction F-18 is produced by 18O(p, n)18F nuclear reaction followed by a radiofluorination to give [18F]FDG [1]. For increasing the F-18 production yield, many scientists have made a research on the water target
[2,3]. Mainly there are two way; one is cooling efficiency increase and other is increasing irradiation currents. In this study, the variation of water target inside was observed when the proton beam irradiated to find a optimize operation condition. 2. Method
*
Corresponding author. Tel.: +82 2 970 1335; fax: +82 2 970 1332. E-mail address: [email protected] (M.-G. Hur).
The test target was assembled like Fig. 1. The target and front window foil was made by
0168-583X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2005.07.173
736
M.-G. Hur et al. / Nucl. Instr. and Meth. in Phys. Res. B 241 (2005) 735–737
Fig. 1. Schematic drawing for test target.
titanium. For observation of target inside, back window was made by quartz and Panasonic GP-KS162HD CCD camera was installed to monitor this. The experimental conditions are like this: (1) proton beam current: 1–23 lA, increment 1 lA in one additional minute, (2) cooling: one side water cooling, flow late 5 L/min at 23 °C, (3) target has sealed by Swagelok SS42 valve.
3. Results 3.1. Pressure and bubble float
Fig. 3. Bubble floats during proton beam irradiation (0.25 s interval).
tured figure of bubble float is shown in Fig. 3. In closed target system experiments during bombardment, circulation of gas phase looks like bubble which has been presented at the top of target cavity was observed. The bubbles are scattered followed by causing pressure rising with current increasing. As a result of this, it turned out that the target can absorb the initial proton energy completely and there arises no need to have an additional energy degradation length.
The correlation between irradiation current, pressure and temperature is shown in Fig. 2. In this figure, the graph can be divided into three areas; first is over cooling area, second is heating area and third is over heating area. If given more cooling, the heating area will be expanded and make high current irradiation possible. The cap-
3.2. Gas phase and target deformation
Fig. 2. Behavior of pressure and temperature versus irradiation current.
Fig. 4. Behavior of gas phase ratio versus irradiation current to H218O.
Fig. 4 is a graphical view of gas phase increasing. The growth of gas phase is increasing the deformation of window foil. The grown gas phase ironically has made lower the area where the proton beam irradiated. That cause of accelerating
M.-G. Hur et al. / Nucl. Instr. and Meth. in Phys. Res. B 241 (2005) 735–737
737
pressure rising against that reduces cooling area. For more safety operation, target should be restrained by the pressure with high cooling and wide heat transfer area or mechanically restricted the deformation of window foil.
sequently, RI production yield of F-18 water target can be predicted depending on this saturate value. For designing a high yield water target, suppression of the target windows and improvement of the cooling efficiency are required.
4. Conclusion
References
In conclusion, the target has three modes when proton beam irradiated. In over heating area, it has been found that the target has a saturation point against the irradiation current to the liquid phase due to bulging of the target windows. Con-
[1] G. Stocklin, V.W. Pike, Radiopharmaceuticals for Positron Emission Tomography, Kluwer Academic Publishers, 1993. [2] S.-J. Heselius, D.J. Schlyer, A.P. Wolf, Appl. Radiat. Isot. 40 (1989) 663. [3] E. Hess, G. Blessing, H.H. Coenen, S.M. Qaim, Appl. Radiat. Isot. 52 (2000) 1431.