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4.5  CYCLOTRON-PRODUCED RADIONUCLIDES

The radionuclides
201
Tl, 67Ga,
respective target materials on high-beam-current cyclotrons owned and operated by commercial entities[9] (ref. Tec Doc 468). The typical cyclotron has a maximum proton energy of approximately 30 MeV and beam currents typically greater than 200 μA, with some as high as 1 mA. Such cyclotrons have remotely operated target changers to lower the radiation exposure to sta.
123
I, and
111
In are made by proton bombardment of their
Figure 4.2 I-131
usage based on US Medicare ben­eciaries (National
Research Council [NRC]). Note that
1 mCi is equivalent to 37 GBq. Source: Based on NRC (National Research Council). 2016.
Molybdenum-99 for
Medical Imaging.
shington,
Wa DC: The National
cademies
A Press. Avail­able https://doi.
org/10.17226/23563.

4.6  THALLIUM-201

Thallium has a + 1-oxidation state, making it a useful analog of potassium. It is used exten­sively in cardiac imaging even though there are lower radiation exposure to the patient and can be prepared from generator-produced
99m
Tc[10].
With a half-life of 73.06 hours,
201
Tl can be produced in a central location and shipped
to end users at great distances. Tl-201 decays by electron capture with the emission of gamma rays at 167 and 135 keV, which are ideal for use in a gamma camera[11–13].
99m
Tc-tracers (see Table4.2) that deliver
Chapter 4: Production of Radionuclides Used in SPECT 75
1600
Cross-section (mb)
Particle energy (MeV)
Figure 4.3 Pb-201
production cross-section for the eventual
extraction of
201
Tl.
Source: Based on IAEA charged
particle cross sec­tion database for medical radioiso­tope production, updated 2003–
2004. www-nds.
iaea.org/medical.
1400
1200
1000
800
600
400
200
203
TI(p,3n)
201
Pb
Bonardi (83)b Harmanne (92) Lagunas-S. (78) Qaim (79) fit Spline Hermanne (91)
0
15 20 25
The production cross-section is shown in Figure4.3, which is for the
201
Pb reaction. The
201
Tl is obtained by waiting for the 9.3 hour
30 35
201
Pb to decay approxi-
203
Tl(p,3n)
mately 32 hours (more than three half-lives). There are two stable isotopes of thallium:
203
Tl (29.52%) and
205
Tl (70.48%). Thus, the target for producing
201
Tl must be enriched
in Tl=203.
Two methods that are generally used to achieve the separation and isolation of
201
Tl
from the Tl/Pb target mixture may include ion-exchange resins and solvent/solvent
extraction. The detailed procedure for the extraction can be found in International Atomic Energy Agency (IAEA) Technical Report Series 432[15].
Because the target is composed of enriched
203
Tl (>97% to >98%),1 it must be sepa-
rated from the Pb isotopic product using chemical and electrodeposition methods.
For clinical use, the nal product is checked for radionuclidic and chemical purity using multichannel pulse-height analysis with a gamma spectrometer. In addition to the
201
Tl
gamma peaks, the impurities are also determined. The main gamma peaks are the X-rays (70.8 and 80.2 keV) and photons (135 and 167 keV) of photons (439 keV) of
The radiochemical purity of the entiate TI
201
Tl solution by spectrophotometric adsorption analysis[16, 17]. Figure4.4 illustrates the
+
and Tl3+[16]. Chemical purity is assessed for the quantity of hydrazine in the
202
Tl.
201
Tl is checked by paper chromatography to dier-
201
Tl; photons (368 keV) of
200
Tl; and
potential radionuclidic impurities found in the target mix, which are highly dependent upon the irradiation energy and length of irradiation[18].
Pb-200 (21.5 hours) decays to
200
Tl (26 hours), and
202m
Pb (3.54 hours) decays to
202
Tl
(12 .23 day s ).
76 Handbook of Radiopharmaceuticals
1
All enrichments are typical and provided by Isoex, San Francisco, California.
Figure 4.4 Yield curves for
proton reactions on Tl isotopes found in the enriched
200,201,202m
Pb based on excitation curves or the three
203
Tl target. Source: Tárkányi, F.T., Ignatyuk, A.V., Hermanne, A. etal. Recommended nuclear data for medical radioisotope production: diagnostic gamma emitters. J Radioanal Nucl Chem 319, 487–531 (2019). Licensed under CCBY 4.0.

4.7  GALLIUM-67

Gallium-67 (t
=3.26 days) behaves in the body similarly to ferric iron and is often used
1/2
as a trivalent citrate compound for imaging in the detection and localization of certain neoplasms and inammatory lesions. It decays to stable
67
Zn by electron capture.
The decay emissions include gamma-rays of 93.3 keV (37.0%), 184.6 keV (20.4%), and
300.2 keV (16.6%).
Figure4.5 shows the excitation function for the production of
reaction. An enriched
68
Zn target is required because of the large number of stable zinc
67
Ga via the 68Zn(p,2n)
isotopes. The target is often plated onto a copper backing plate for irradiation in the
cyclotron.
There are several methods for the separation of
67
Ga from the zinc target. Two commonly used methods entail ion-exchange separation and solvent/solvent extrac­tion[19, 20].
After irradiation, the
tion of Ga-67 from
68
Zn target is dissolved in concentrated HCl, followed by separa-
68
Zn by Dowex 50W-X8 resin. Ga-67 is recovered as Ga-citrate by dis-
solving the residue in a solution of 2–4% sodium citrate solution.
For the alternative approach, the irradiated
68
Zn target is dissolved in 7.5 M HCl, fol-
lowed by extraction of Ga-67 in di-isopropyl ether (DIPE). Zn-68 remains in the acidic
Chapter 4: Production of Radionuclides Used in SPECT 77
Cross-section (mb)
1000
Particle energy (MeV)
50
Figure 4.5 Exci-
tation function for the production of
67
Ga. Source: Based
on IAEA charged
particle cross sec­tion database for medical radioiso­tope production, updated 2003–
2004. www-nds.
iaea.org/medical.
68
800
600
400
200
0
10 20 30
Zn(p, 2n)67 Ga
Cohen 1955 Bonardi (natZn) 1983 Tá rkányi 1990
Levkovskij (x0.8) 1991 Nortier (natZn) 1991
Hermanne (68Zn) 1997 Hermanne (natZn) 1997 Szelecsényi 1998 Hermanne (68Zn) 1999 Hermanne (natZn) 1999 Stoll 2002 Szelecsényi (68Zn) 2005
Szelecsényi (natZn) 2005 Fit (Spline)
40
aqueous layer. Ga-67 is back-extracted from DIPE with a small volume of sterile water. To the solution containing Ga-67 is added 0.5 ml of 2.5% sodium citrate, and the solution is carefully evaporated to dryness. The residue is dissolved in saline containing a sucient amount of sodium citrate for radiopharmaceuticals manufacturing[21].
For the recovery of the enriched
68
Zn, the acidic aqueous layer containing the target
material is allowed to decay for approximately a month and pooled together from mul­tiple targets. Zn-68 is precipitated as zinc sulde with a Na
S solution, followed by disso-
2
lution in concentrated HCl. Zn-68 is precipitated from the acid solution as zinc hydroxide by adding sucient NaOH to attain basic pH[6–8]. Controlled drying provides
68
Zn as an
oxide, which is used to prepare additional targets.
The radionuclidic impurity levels in the separated gallium citrate depend upon the
radioisotopic enrichment of the target material and the eciency of the separation
method. Co-production of high-energy
66
Ga (9.3 hours; through p,2n reaction) should
also be taken into account while processing the irradiated target. Sucient time must be allowed post-irradiation for the short-lived Ga isotopes to decay to an acceptable level (pharmacopeia standard). Final
67
Ga products must have low levels of contaminants
within acceptable human toxicity[22] and pharmacopoeial limits.
It is essential to ensure through chromatographic method a lower than acceptable
level of free
67
Ga (<5%) and assurance of >95% as Ga-citrate.
78 Handbook of Radiopharmaceuticals

4.8  INDIUM-111

Because indium forms stable chelates, it is used to label large molecules for imaging and
therapy despite relatively poor decay emissions. In-111 decays by electron capture with a half-life of 2.83 days. There are two prominent gamma rays: 71.3 and 245.4 keV[15]. Table4.3 provides a list of the primary
111
In radiopharmaceuticals[1].
Radiopharmaceutical Trade name Primary use
30
Particle energy [MeV]
Cross-section [mb]
Uncertainty [%]
Indi u m -111 chlor ide Indiclor In-111C l Labeling monoclonal antibodies
and peptides (OncoScint and Octreoscan)
Indium-111 pentetate (DTPA) Indium DTPA In-111 Imaging of cerebrospinal uid
kinetics Indium-111 oxyquinoline (oxine) Indi u m -111 oxin e Labeling leukocytes and platelets Indium-111 capromab pendetide ProstaScint Monoclonal antibody for imaging
prostate cancer
Indium-111 pentetreotide Octreoscan Imaging neuroendocrine tumors
Source: Based on NRC (National Research Council). 2007. Advancing Nuclear Medicine Through Inno- vation. Washington, DC: The National Academies Press. Available at https://doi.org/10.17226/11985.
The target material is enriched Cd-112 (typically >98%). It can be either electroplated
or pressed as a powder into a target holder (see target preparation) [15].
Enriched
112
Cd as a metal is used to produce
111
In from the
112
Cd(p,2n) reaction. The exci-
tation function is shown in Figure4.6[14].
In-111 is isolated from the cadmium target by dissolving in acid, separated by solvent extraction, and further puried by a second step extraction. An alternative approach uses ion-exchange chromatography. Both methods give similar recoveries of the
To recover enriched target material, the pooled solution containing
111
In[23].
112
Cd from several
irradiated targets is boiled to remove residual organic solvent and made basic to pre-
cipitate
followed by dissolution in concentrated HCl. Cd is then reprecipitated as Cd(OH)
112
Cd (pH > 12). Cd-112 is precipitated as a sulde with sodium sulde solution
with a
2
base. The hydroxide can be converted to oxide by heating at 90–130°C.
Table 4.3
List
ofcommercial Indium-111 radio-
pharmaceuticals.
1000
500
112
Cd(p, 2n)
0
5
111
In
10 15 20 25 30 35
[104] Otozai 1966 [106] Skakun 1975 [107] Nortier 1990 [108] Ta rkanyi 1994 [109] Ta rkanyi 2006 [110] Khandaker 2008 [111] AI-Saleh 2008 [112] Hermanne 2014 fit Pade fit uncertainty
Chapter 4: Production of Radionuclides Used in SPECT 79
20
10
0
Figure 4.6 Exci-
tation function for the production of
111
In. Source: Based
on IAEA charged
particle cross sec­tion database for medical radioiso­tope production, updated 2003–
2004. www-nds.
iaea.org/medical.
Physico-chemical tests for
111
InCI3 can be carried out to check the quality of the nal
product. The radionuclidic purity of the nal product is checked by gamma-ray spectros­copy. Radiochemical purity is assessed by paper chromatography[24, 25]. The chemical purity of the nal product is tested by checking for the presence of Cu, Fe, and Al[26].

4.9  IODINE-123

I-123, with a half-life of 13.2 hours, is probably the most widely used cyclotron-produced
radiohalogen. It has gradually replaced
pharmaceuticals containing radioiodine. It gives a much lower radiation dose to the patient due to the shorter half-life and lower gamma-ray energy of 159 keV. This photon energy is ideally suited for use in a SPECT camera[8]. Like the photons from gamma ray penetrates tissue very eectively without an excessive radiation dose. For this
reason, it has, in many instances, replaced reactor-produced
pharmaceuticals have been labeled using
The preferred method for preparing
of enriched
124
Xe. This approach produces three isobars–
lives of 5.9 minutes, 2.1 hours, and 13.2 hours, respectively.
The enriched
124
Xe (>99.8%) target material is a gas, and the target vessel typically con­tains 1–2 l of gas at elevated pressure. The real danger here is the possibility of rupturing a foil, which may result in the loss of the target gas into the cyclotron and then into the atmosphere. Several designs have been published to reduce or eliminate the possibility of such a loss[27–32]. In most cases, the xenon gas is trapped in a loop contained at liquid nitrogen temperatures. These loops, if properly constructed, can trap more than 99% of the xenon gas in the targets. This type of target has been tested extensively and has proven to be reliable in routine operation (Figure4.7).
The separation of the radioiodine from the target matrix is accomplished by isolating
123
the
Xe from the matrix; it is then allowed to decay to
aration is usually not dicult since the xenon is very unreactive and can generally be
readily extracted from the target.
During much of the 1970s and 1980s,
(99.90–99.93%) via the
124
Te(p,2n) reaction (see Figure4.8). The targets were prepared by
electrodeposition of metallic tellurium or by using tellurium oxide in a pressed target.
131
I as the isotope of choice for diagnostic radio-
99m
Tc, the
131
I. A great number of radio-
123
I, and the number is increasing (see Table4.4).
123
I with high specic activity is via the irradiation
123
123
Cs,
Xe, and
123
I in a separate vessel. This sep-
123
I was produced by bombarding enriched
123
I–with half-
124
Te
Table 4.4 Exam-
ples of some
123
I radiophar-
maceuticals.
123
I–radiopharmaceutical Application
o-Iodohippuran Renal function imaging N-Isopropyl-p-iodoamphetamine Cerebral blood-ow imaging
Iododeoxyuridine Cancer imaging p-Iodophenylalanine Glioma imaging and therapy Octreotide Targets somatostatin receptors
Source: Based on NRC (National Research Council). 2007. Advancing Nuclear Medicine Through Inno­vation. Washington, DC: The National Academies Press. Available at https://doi.org/10.17226/11985.
80 Handbook of Radiopharmaceuticals
30
1000
Particle energy [MeV]
Cross-section [mb]
Uncertainty [%]
Particle energy [MeV]
Cross-section [mb]
800
600
400
200
Figure 4.7
124
Xe(p,x)
123
Xe
[113] Kurenkov 1989 [115] Hermanne 2011 fit Pade fit uncertainty
20
Cumulative exci­tation function
for producing
123
Xe, including
direct and decay
processes. Source: Based on IAEA charged particle
10
cross section data­base for medical radioisotope pro­duction, updated 2003–2004.
0
10
20 30
0
40
www-nds.iaea.
org/medical.
1200
124
Te(p,2n)
1000
800
600
400
200
0
10 15 20 25 30
Solid targets made from powdered tellurium have also been widely used for the
production of
123
I[33–41]. The tellurium powder has often been mixed with aluminum
123
I
Kondo (77a)
Kondo (77b)
Scholten (95) Spline (04)
powder to increase the heat-transfer characteristics of the target. A common problem with these targets is melting of the elemental tellurium and consequent loss of the radio-
iodine from the matrix.
Other types of alloy targets have been used for the production of
123
I, such as a tellu-
rium–gold alloy[41]. This technique has been used extensively when the thermal conduc­tivity of the primary material is low and/or the melting point is low. Tellurium oxide has
also been used to produce
therefore, a low loss of iodine from the matrix during irradiation.
123
I. The oxide has the advantage of a high melting point and,
Figure 4.8 Exci-
tation function for the production
123
of
I from the bombardment of enriched
124
Te.
Source: Based on IAEA charged
particle cross sec­tion database for medical radioiso­tope production, updated 2003–
2004. www-nds.
iaea.org/medical.
Chapter 4: Production of Radionuclides Used in SPECT 81
With this method,
123
I was isolated through dry or wet distillation or through a chemical
process. A common method of extraction is the use of dry distillation. In this approach, the
tellurium powder or tellurium oxide powder is heated to near the melting point with a ow of gas over the plate. The
123
I is distilled out of the matrix and carried by the sweep gas to a collection vessel, where it is trapped. This vessel usually contains a base solution, and the iodine is in the chemical form of iodide. A wet chemical method can also be used by dissolv­ing the Te and then oxidizing the iodide to iodine and distilling it from the solution[33].
Te-124 can be recovered through a straightforward chemical process. Te-124 from a number of targets after a lengthy cooling period is dissolved in a HCl/hydrogen peroxide mixture, followed by reduction of Te
+6
to Te+4 with acid, and then free tellurium metal is
precipitated by the addition of hydrazine hydrate and sodium sulte[15].
I-123 produced through the (p,2n) reaction on enriched
produced
124
I, which limits the shelf-life of products prepared from the direct production
124
Te is contaminated with co-
method. Thus, the radionuclidic purity must be assessed before further use.
In addition, it is essential to monitor and control the presence of several dierent
iodine species, such as iodate and periodate. These species may also be generated during
the storage of high-specic-activity products[42]. Stabilization of radioiodine predomi­nantly as iodide can be achieved by the addition of a small amount of a reductant such as sodium sulte. It should be noted, however, that the presence of a reductant is known to interfere with the radiolabeling of proteins.
Iodine batches produced through irradiation of solid Te and TeO
targets are sub-
2
mitted to chemical purity tests on aluminum and tellurium. Use is made of emission
spectrometry or colorimetry. The iodine batches produced through both targets meetall
criteria of the Pharmacopoeia. The chemical impurities determined by colorimetric spot
tests are typically Te < 0.5 μg mCi
−1
; Al < 0.25 μg mCi−1.

4.A. APPENDIX

References associated with the excitation functions, compiled by the IAEA[18]:
203
Tl(p,3n)
M. Bonardi, C. Birattari, and A. Salomone.
nuclear reactions on Tl and Hg natural and enriched targets. Proc. Int. Conf. Nuclear
Data for Science and Technology, May 1983, Antwerp, Belgium (ed. K.H. Bockho),
1983, pp. 916–918.
Additional information in: F. Girardi, L. Goetz, E. Sabbioni, E. Marafante, M. Merlini, E
Acerbi, C. Birattari, M. Castiglioni, and F. Resmini. Preparation of
studies on pathways and eects of lead pollution. Int. J. Appl. Rad. Isot 26 (1975) 267.
68
Zn(p,2n)67Ga
Results of measurements for the
between 17 and 30 MeV. In this energy range, the contribution of the
82 Handbook of Radiopharmaceuticals
201
Pb
201
Tl production for medical use by (p,xn)
203
Pb compounds for
nat
Zn(p,xn)67Ga process can be used for evaluation
67
Zn(p,n)67Ga
reaction can be neglected due to the low isotopic abundance of 67Zn in a natural zinc
matrix and the magnitude of the cross-section of the
inuence of the
70
Zn(p,4n)67Ga process to the production cross-sections is also negli-
gible because of the very low isotopic abundance of
67
Zn(p,n)67Ga reaction. The
70
Zn in natural zinc (0.62%).
B.L. Cohen and E. Newman. (p,pn) and (p,2n) cross sections in medium weight elements. Phys. Rev. 99 (1955) 718. Exfor: B0050.
M. Bonardi and C. Birattari. Optimization of irradiation parameters for
nat
from
Zn(p,xn) nuclear reactions. J. Radioanal. Chem. 76 (1983) 311. Exfor: O1062.
67
Ga production
F. Tarkanyi, F. Szelecsenyi, Z. Kovacs, and S. Sudar. Excitation functions of proton
induced nuclear reactions on enriched
66
Zn, 67Zn and 68Zn. Production of 67Ga and 66Ga.
Radiochim. Acta 50 (1990) 19. Exfor: D4004. V.N. Levkovskij. Activation cross section nuclides of average masses (A=40–100) by pro-
tons and α-particles with average energies (E=10–50 MeV), book: Levkovskij, Activation cross section by protons and alphas, Moscow, 1991. Exfor: A0510 Cross- sections must be normalized by a factor of 0.8, as was pointed out in S. Takács, F. Tárkányi, M. Sonck, and A. Hermanne. Investigation of the
nat
Mo(p,x)
96mg
Tc nuclear reaction to monitor
proton beams: new measurements and consequences on the earlier reported data. Nucl. Instrum. Methods B 198 (2002) 183.
F.M. Nortier, S.J. Mills, and G.F. Steyn. Excitation functions and yields of relevance to
the production of
67
Ga by proton bombardment of
nat
Zn and
nat
Ge up to 100 MeV. Int.
J.Radiat. Appl. Instrum. Part A 42 (1991) 353. Exfor: A0498. A. Hermanne. Evaluated cross section and thick target yield data of Zn+p processes for
practical applications. Private communication (1997). Exfor: D4093 Target: natural Zn
and enriched
68
Zn.
F. Szelecsényi, T.E. Boothe, S. Takács, F. Tárkányi, and E. Tavano. Evaluated cross sec­tion and thick target yield data bases of Zn+p processes for practical applications. Appl. Radiat. Isot. 49 (1998) 1005.
A. Hermanne, F. Szelecsenyi, M. Sonck, S. Takacs, F. Tarkanyi, and P. Van Den Winkel. New cross section data on
68
Zn(p,2n)67Ga and
nat
Zn(p,xn)67Ga nuclear reactions for
the development of a reference data base. J. Radioanal. Nucl. Chem. 240 (1999) 623. Exfor: D4088.
T. Stoll, S. Kastleiner, Yu.N. Shubin, H.H. Coenen, and S.M. Qaim. Excitation functions
of proton induced reactions on ence to the production of
68
Zn from threshold up to 71 MeV, with specic refer-
67
Cu. Radiochim. Acta 90 (2002) 309.
F. Szelecsényi, G.F. Steyn, Z. Kovács, T.N. van der Walt, K. Suzuki, K. Okada, and K.Mukai. New cross-section data for the
68
Zn(p,2n)67Ga and
nat
Zn(p,x)67Ga nuclear reactions up to 100 MeV. Nucl. Instrum.
66
Zn(p,n)66Ga, 68Zn(p,3n)66Ga,
nat
Zn(p,x)66Ga,
Methods B 234 (2005) 375. Exfor: E1935.
Chapter 4: Production of Radionuclides Used in SPECT 83
111
Cd(p,2n)
111
In
K. Otozai, S. Kume, A. Mito, H. Okamura, R. Tsujino, Y. Kanchiku, T. Katoh, and H. Gotoh.
Excitation functions for the reactions induced by protons on Cd up to 37 MeV. Nucl.
Phys. 80 (1966) 335. Exfor: P0019.
E.A. Skakun, A.P. Kljucharev, Yu.N. Rakivnenko, and I.A. Romanij. Excitation functions
of (p,n)- and (p,2n)-reactions on cadmium isotopes. Izv. Rossiiskoi Akademii Nauk, Ser.
Fiz. 39 (1975) 24.
F.M. Nortier, S.J. Mills, and G.F. Steyn. Excitation functions and production rates of
relevance to the production of
111
In by proton bombardment of
nat
Cd and
nat
In up to
100 MeV. Int. J. Radiat. Appl. Instrum. Part A 41 (1990) 1201.
F. Tárkányi, F. Szelecsényi, P. Kopecký, T. Molnár, L. Andó, P. Mikecz, Gy. Tóth, and
A.Rydl. Cross sections of proton induced nuclear reactions on enriched
for the production of
111
In for use in nuclear medicine. Appl. Radiat. Isot. 45 (1994) 239.
111
Cd and
F. Tárkányi, B. Király, F. Ditrói, S. Takács, J. Csikai, A. Hermanne, M.S. Uddin, M.
Hagiwara, M. Baba, T. Ido, Yu.N. Shubin, and S.F. Kovalev. Activation cross-sections on
cadmium: proton induced nuclear reactions up to 80 MeV. Nucl. Instrum. Methods B
245 (2006) 379.
M.U. Khandaker, K. Kim, M.W. Lee, K.S. Kim, G.N. Kim, Y.S. Cho, and Y.O. Lee.
Production cross-sections for the residual radionuclides from the
nat
Cd(p,x) nuclear
processes. Nucl. Instrum. Methods Phys. Res. B266 (2008) 4877–4887.
F.S. Al-Saleh. Cross sections of proton induced nuclear reactions on natural
cadmium leading to the formation of radionuclides of indium. Radiochim. Acta 96
(2008) 461–465.
A. Hermanne, R. Adam-Rebeles, P. Van den Winkel, F. Tárkányi, and S. Takács.
Production of
111
In and
114m
In by proton induced reactions: an update on excita­tion functions, chemical separation-purication and recovery of target material. Radiochim. Acta 102 (2014) 1111–1126.
112
Cd
124
Xe(p,2n)
123
Cs/
124
Xe(p,pn)
N.V. Kurenkov, A.B. Malinin, A.A. Sebyakin, and N.I. Venikov. Excitation functions of
proton-induced nuclear reactions on
135 (1989) 39–50. F. Tárkányi, S.M. Qaim, G. Stocklin, M. Sajjad, R.M. Lambrecht, and H. Schweickert. Exci-
tation functions of (p,2n) and (p,pn) reactions and dierential and integral yields of
123
I in proton induced nuclear reactions on highly enriched
(1991) 221–228. A. Hermanne, F. Tárkányi, S. Takács, R. Adam-Rebeles, A. Ignatyuk, S. Spellerberg,
andR. Schweikert Limitation of the long-lived
123
I through the
124
Xe(p,x) route. Appl. Radiat. Isot. 69 (2011) 358–368.
84 Handbook of Radiopharmaceuticals
123
Xe
124
Xe: production of
121
Te contaminant in production of
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