Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT
This paper presents the preliminary results on determining the values of specific activity of radionuclides ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re. Irradiation of Re targets of a natural isotope composition with gamma-quanta and neutrons was conducted at NSC KIPT linear accelerators. Possible levels of activity of...
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2001
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| Cite this: | Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT / A.N. Dovbnya, N.P. Dikii, A.S. Zadvornyi, G.P. Kovtun, A.V. Torgovkin, B.I. Shramenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 203-205. — Бібліогр.: 4 назв. — англ. |
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Dovbnya, A.N. Dikii, N.P. Zadvornyi, A.S. Kovtun, G.P. Torgovkin, A.V. Shramenko, B.I. 2015-03-24T18:50:04Z 2015-03-24T18:50:04Z 2001 Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT / A.N. Dovbnya, N.P. Dikii, A.S. Zadvornyi, G.P. Kovtun, A.V. Torgovkin, B.I. Shramenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 203-205. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS number: 25.20.Lj https://nasplib.isofts.kiev.ua/handle/123456789/79030 This paper presents the preliminary results on determining the values of specific activity of radionuclides ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re. Irradiation of Re targets of a natural isotope composition with gamma-quanta and neutrons was conducted at NSC KIPT linear accelerators. Possible levels of activity of the above-mentioned radionuclides are forecasted. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT Возможность получения изотопов 184Re, 186Re и 188Re на линейных ускорителях электронов ННЦ ХФТИ Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT |
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Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT Dovbnya, A.N. Dikii, N.P. Zadvornyi, A.S. Kovtun, G.P. Torgovkin, A.V. Shramenko, B.I. |
| title_short |
Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT |
| title_full |
Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT |
| title_fullStr |
Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT |
| title_full_unstemmed |
Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT |
| title_sort |
production of isotopes ¹⁸⁴re, ¹⁸⁶re and ¹⁸⁸re at linear electron accelerators of nsc kipt |
| author |
Dovbnya, A.N. Dikii, N.P. Zadvornyi, A.S. Kovtun, G.P. Torgovkin, A.V. Shramenko, B.I. |
| author_facet |
Dovbnya, A.N. Dikii, N.P. Zadvornyi, A.S. Kovtun, G.P. Torgovkin, A.V. Shramenko, B.I. |
| publishDate |
2001 |
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English |
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Вопросы атомной науки и техники |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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| title_alt |
Возможность получения изотопов 184Re, 186Re и 188Re на линейных ускорителях электронов ННЦ ХФТИ |
| description |
This paper presents the preliminary results on determining the values of specific activity of radionuclides ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re. Irradiation of Re targets of a natural isotope composition with gamma-quanta and neutrons was conducted at NSC KIPT linear accelerators. Possible levels of activity of the above-mentioned radionuclides are forecasted.
|
| issn |
1562-6016 |
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https://nasplib.isofts.kiev.ua/handle/123456789/79030 |
| citation_txt |
Production of isotopes ¹⁸⁴Re, ¹⁸⁶Re and ¹⁸⁸Re at linear electron accelerators of NSC KIPT / A.N. Dovbnya, N.P. Dikii, A.S. Zadvornyi, G.P. Kovtun, A.V. Torgovkin, B.I. Shramenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 203-205. — Бібліогр.: 4 назв. — англ. |
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2025-11-24T16:18:09Z |
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| fulltext |
PRODUCTION OF ISOTOPES 184Re, 186Re AND 188Re AT
LINEAR ELECTRON ACCELERATORS OF NSC KIPT
A.N. Dovbnya, N.P. Dikii, A.S. Zadvornyi, G.P. Kovtun, A.V. Torgovkin, B.I. Shramenko
IHEPNP NSC KIPT
Akademicheskaya 1, Kharkov, Ukraine
This paper presents the preliminary results on determining the values of specific activity of radionuclides 184Re, 186Re
and 188Re. Irradiation of Re targets of a natural isotope composition with gamma-quanta and neutrons was conducted
at NSC KIPT linear accelerators. Possible levels of activity of the above-mentioned radionuclides are forecasted.
PACS number: 25.20.Lj
It is known that in the world nuclear medicine more
than 80 % of diagnostic means are radiopharmaceuticals
based on 99mTc. Developed-to-perfection technologies
for commercial production of 99Mo →99mTc generators
are based on a reactor method of 99Mo production. How-
ever, due to a comparatively short half-period of 99mTc,
as well as, quick accumulation of its decay product—
99Tc, deteriorating the diagnosis quality this element can
not be put in a row of ideal ones [1].
Therefore, in the world practice one observes a ten-
dency to discover new radionuclides having higher
characteristics as labels for radiopharmaceuticals [2].
For example, one of promizing radionuclides is an iso-
tope 186Re having, as compared with 99mTc, a higher
complex-forming ability and a high tropy characteristic.
An optimum value (137 keV) of the energy of γ-quanta
emitted, short half-period and absence of accompanying
radiation makes this isotope rather promising. The
present work is aimed for obtaining the data on the val-
ues of the specific activity of Re isotopes produced at
NSC KIPT accelerators under different irradiation con-
ditions.
As targets for isotope production we have used
metallic Re in the form of plates and fine dispersed
powder. The chemical purity of initial targets was no
less than 99.99%. The targets were packed in containers
from the aluminum foil 0.1 mm thick.
Accelerators were operating under the following ir-
radiation conditions:
• electron energy – 25 MeV; 11.5 MeV
• mean beam current – 500 µА;
• irradiation time – 20 hours; 105 min.
Prepared and weighed sample-targets were placed at
the accelerator EPOS at a distance of ~90 cm from the
excit foil of the accelerator. The cassetes with other tar-
get after radiation treatment were placed ahead of the
samples. Such arrangement of rhenium targets is caused
by the necessity to carry out simultaneous seances of ir-
radiation in conformity with different radiation pro-
grammes that enables one to use the “spent” electron
beam. At the accelerator KUT similar targets from Re
were placed ahead other targets immediately under the
electron beam. A bremsstrahlung converter was not set
in order not to disturb the radiation conditions for simul-
taneously conducted irradiating programmes.
The specific activity of targets was determined by
measuring, on a spectrometric bench, of a number of γ-
quanta in the given energy range with a known acceler-
ated electron current density in the site of samples. The
similar technique of measurements and data processing
was applied in [3]. A measuring bench was completed
with a Ge(Li) semiconductor detector DGDK-100A of a
100 cm3 volume. The energy resolution of the detector
is 2.3 keV, detected by 60Co γ–lines.
For mathematical data processing we have used the
programmes determining the sum under the peak of full
photoabsorption with subtraction of the approximated
background. To obtain the necessary accuracy we have
used the method of least squares that makes it possible
to approach the experimental data by the exponential
curve in the form ( )A A t= −0 exp λ , where λ is the de-
cay constant, t is the time after irradiation stopping, А0
is the activity at an instant of irradiation stopping.
Miscalculations were counted by the following for-
mula:
( )1s
0 tN1
NN
τ⋅−
= , (1)
where N is the number of photons in the photopeak de-
tected by the detector, N0 is the real number of photons,
Ns is the total number of pulses in the spectrometric
channel, τ is the dead time of the spectrometer, t1 is the
exposition time of spectrum. The error of N0 includes
the error of the sum value under the photopeak σn0, the
error due to the given exposition time of spectrum σt,
and the error due to subtraction o f t h e background σ
f . The total error is determined as a mean-square value
of all the components.
2
f
2
t
2
0ntot σ+σ+σ=σ . (2)
The main contribution into the total error is made by
σ n0 and σ f [ 4 ] :
( ) ( )
f
1f
f
0
10
0n N
tN1
N
tN1 τ⋅+
=σ
τ⋅+
=σ , , (3)
( ) 010t NtexpN ⋅λ−⋅=σ . (4)
When evaluating the sample activity, the detector ef-
ficiency η was the essential factor. It was determined as
a relationship between the quantity of quanta detected in
the photopeak and the quantity of quanta radiated from
the γ-source with a known activity. With such determi-
nation of the efficiency it was not necessary to evaluate
in each case a solid angle being covered by the detector
when changing the source position. To determine η we
have used a set of standard γ-sources comprising 22Na,
137Cs, 54Mn, 241Am with energies of γ-lines 511, 1275,
661, 834, 59.5 KeV, respectively.
203
Results on the detector efficiency measured as a
function of the γ-quantum energy at different distances
from the source are represented in Fig. 1.
Fig. 1. Detector efficiency as a function of γ-quan-
tum energy at different distances from the source:
5.5 mm, 60 mm, 100 mm.
The radionuclide activity А0 at the instant of irradia-
tion stopping was calculated by the formula
t0
ekmIη
AA
⋅λ−⋅⋅⋅⋅
= (Bq/g⋅µА), (5)
where η is the efficiency of γ-quantum detection, I is
the average current falling onto the sample, А0 is the
specific activity of the sample at the instant of stopping
irradiation, m is the target mass, k is the coeffcient of γ-
quantum multiplicity, A is the number of γ-quanta de-
tected in the time t after irradiation stopping, λ is the ra-
dionuclide decay constant.
Initially irradiation of the Re sample in the form of a
plate was performed at the accelerator EPOS. When
measuring the activity of samples in the form of a plate
the essential factor is the γ-irradiation absorption with
an energy of 137 keV in the target material. For the data
be more accurate we have carried out irradiation of Re
samples in the form of a powder at the accelerator KUT
with an electron beam energy of Е0 =11.5 MeV. Selec-
tion of a powdered target significantly decreases the in-
fluence of γ-radiation absorption in the target material
on evaluation of the specific activity.
Under irradiation of Re samples having a natural
isotope composition: 185Re(37%) and 187 Re(63%), as a
result of γ,n reactions, isotopes 184Re and 186 Re are
formed (Table 1).
Table 1.
Nuclear reaction Т 1/2 Е thres
MeV
Еγ, keV
(intens.)
185Re(γ,n) 184Re 38 days 7.8 111(17%)
792(36%)
894(16%)
903(36%)
187Re (γ,n) 186Re 90 hours 7.3 137(12%)
185Re (n,γ) 186Re 90 hours - 137(12%)
187Re (n,γ) 188Re 17 hours - 155(21%)
In Fig. 2 shown is a part of the radiation spectrum of
the Re sample irradiated at the accelerator KUT during
105 min. For the illustration be clearer the γ-lines of
184Re with energies of 792 and 903 keV are not shown.
40 60 80 100 120 140 160 180 200
0
1000
2000
3000
4000
188184Re(111keV)
186Re (137 keV)
(57keV, 66keV)184Re
Re(155keV)In
te
ns
ity
Energy, keV
Fig. 2. Spectrum of Re irradiated at the accelerator
KUT.
An important result is the presence of the 155 keV
peak belonging to 188Re. This isotope formed from 187Re,
as a result of neutron capture, has comparatively short
half-life and is interesting for radiological investiga-
tions. A traditional method of 188Re production is the
188W based generator obtained in nuclear reactors from
186W (28%) by the scheme 186W (n,γ)→ 187W(n,γ) →
188W(69 days) → 188Re. Such a two-step process of 188W
production requires availability of high-intensity neu-
tron flows and reactor irradiation of long duration. The
results obtained on the 188Re radionuclide shows a possi-
bility to produce this radionuclide at a linear electron
accelerator as an alternative of the reactor method that is
currently urgent for the nuclear medicine of Ukraine. Ir-
radiation of Re targets with neutrons is more preferable
than with γ-quanta because there formed are only iso-
topes 186Re and 188Re without 184Re.
The levels of induced activity of isotopes at the ac-
celerator KUT are calculated by the following data: irra-
diation during 105 min, sample mass is 250 mg, beam is
spread on the area of 300 m2, surface of the Re sample
is 0.3 cm2. We have obtained the following data on the
specific activity of radionuclides: 186Re – 4.3⋅104 Bq/g⋅µ
А, 188Re – 5.3⋅103 Bq/g.µA. At the accelerator EPOS the
samples were irradiated during 20 hours. Rest of param-
eters for calculating the specific activity were similar to
parameters of irradiation at the accelerator KUT. The
value of activity of radionuclide 186Re was 7.2⋅106 Bq/g.
µA. The values of activity allow one to make a conclu-
sion about expedience to continue a research in this di-
rection. Let us note that this experiment was preliminary
since the target irradiation was conducted simultaneous-
ly with other radiating programs without applying com-
plementary converters and neutron-producing targets.
The specific activity of produced isotopes can be in-
creased, firstly, by applying the optimized converter of
bremsstrahlung irradiation (Та (Z=73), thickness ~2
mm); secondly, by increasing the duration of sample ir-
radiation and by focusing the electron beam onto the
converter or neutron-producing target that, according to
calculations, should increase the specific activity ap-
204
proximately by a factor of 103. This enables one to be-
gin experiments on preparing and using farmaceuticals
labelled with isotopes 186Re and 188Re.
REFERENCES
1. R.G.Bennett, J.D.Christian D.A.Petti, W.K.Terry,
S.B.Grover. A system of Tc-99m production based
on distributed electron accelerators and thermal
separation // Nuclear Technology. 1999, v. 126 (1),
p. 102-121.
2. Suresh C. Srivastava. Is There Life After Techneci-
um: What is Potential for Developing New Board-
Based Radionuclides? // Proc. of Seminars in Nu-
clear Medicine. 1996, v. XXXVI, No 2 (April), p.
119-131.
3. G.L.Bochek, A.N.Dovbnya, A.S.Zadvorny et al. //
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ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
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