Electron linac production of Co-57 for gamma-chamber calibration
Gamma-chambers are widely used in medicine diagnostics to obtain an organ image investigated by means of the scintigraphy method. A radionuclide Tc-99m which is accumulated in the organ and irradiates photons with the energy Eγ=140 keV is a carrier of the information. Ukraine manufactures gamma-cham...
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| Zitieren: | Electron linac production of Co-57 for gamma-chamber calibration /N.P. Dikiy, N.A. Dovbnya, O.A. Repikhov, I.N. Shlyakhov, V.L. Uvarov, Ja.N. Kravchenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 200-202. — Бібліогр.: 2 назв. — англ. |
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irk-123456789-790292015-03-25T03:01:59Z Electron linac production of Co-57 for gamma-chamber calibration Dikiy, N.P. Dovbnya, N.A. Repikhov, O.A. Shlyakhov, I.N. Uvarov, V.L. Kravchenko, Ja.N. Gamma-chambers are widely used in medicine diagnostics to obtain an organ image investigated by means of the scintigraphy method. A radionuclide Tc-99m which is accumulated in the organ and irradiates photons with the energy Eγ=140 keV is a carrier of the information. Ukraine manufactures gamma-chambers of own elaboration. A γ-source with a photon energy of Tc-99m but with a larger half-life time is need for their plant calibration. The Co-57 sources (Eγ=122 keV, T1/2=270 days) are the most eligible for this purpose. Their traditional technology is based mainly on the reactor method and is accompanied by the large amount of the radioactive waste. The sources, obtained in such a way, can not be regenerated after their decay. The R&D Complex “Accelerator” of the NSC KIPT developed a new technology and manufactured the model – experimental batch of three Co-57 sources using bremsstrahlung of the high-current electron linac. The Co-57 generation processes in the Ni-58 target were previously investigated by means of computer simulation. The optimum accelerator operation regime and a target geometry were thus determined. The obtained sources characteristics confirmed the computer analysis data. Each of them is the plate of 28x28x1.5 mm and has the activity up to 2 mCi. The spectrum of the source measured with the Ge(Li) detector satisfies all demands. The technology developed provides a production of sufficient amount of Co-57 sources practically without any waste, as well as, a possibility of their regeneration. 2001 Article Electron linac production of Co-57 for gamma-chamber calibration /N.P. Dikiy, N.A. Dovbnya, O.A. Repikhov, I.N. Shlyakhov, V.L. Uvarov, Ja.N. Kravchenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 200-202. — Бібліогр.: 2 назв. — англ. 1562-6016 PACS number: 07.85.Fv http://dspace.nbuv.gov.ua/handle/123456789/79029 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Gamma-chambers are widely used in medicine diagnostics to obtain an organ image investigated by means of the scintigraphy method. A radionuclide Tc-99m which is accumulated in the organ and irradiates photons with the energy Eγ=140 keV is a carrier of the information. Ukraine manufactures gamma-chambers of own elaboration. A γ-source with a photon energy of Tc-99m but with a larger half-life time is need for their plant calibration. The Co-57 sources (Eγ=122 keV, T1/2=270 days) are the most eligible for this purpose. Their traditional technology is based mainly on the reactor method and is accompanied by the large amount of the radioactive waste. The sources, obtained in such a way, can not be regenerated after their decay. The R&D Complex “Accelerator” of the NSC KIPT developed a new technology and manufactured the model – experimental batch of three Co-57 sources using bremsstrahlung of the high-current electron linac. The Co-57 generation processes in the Ni-58 target were previously investigated by means of computer simulation. The optimum accelerator operation regime and a target geometry were thus determined. The obtained sources characteristics confirmed the computer analysis data. Each of them is the plate of 28x28x1.5 mm and has the activity up to 2 mCi. The spectrum of the source measured with the Ge(Li) detector satisfies all demands. The technology developed provides a production of sufficient amount of Co-57 sources practically without any waste, as well as, a possibility of their regeneration. |
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Dikiy, N.P. Dovbnya, N.A. Repikhov, O.A. Shlyakhov, I.N. Uvarov, V.L. Kravchenko, Ja.N. |
| spellingShingle |
Dikiy, N.P. Dovbnya, N.A. Repikhov, O.A. Shlyakhov, I.N. Uvarov, V.L. Kravchenko, Ja.N. Electron linac production of Co-57 for gamma-chamber calibration Вопросы атомной науки и техники |
| author_facet |
Dikiy, N.P. Dovbnya, N.A. Repikhov, O.A. Shlyakhov, I.N. Uvarov, V.L. Kravchenko, Ja.N. |
| author_sort |
Dikiy, N.P. |
| title |
Electron linac production of Co-57 for gamma-chamber calibration |
| title_short |
Electron linac production of Co-57 for gamma-chamber calibration |
| title_full |
Electron linac production of Co-57 for gamma-chamber calibration |
| title_fullStr |
Electron linac production of Co-57 for gamma-chamber calibration |
| title_full_unstemmed |
Electron linac production of Co-57 for gamma-chamber calibration |
| title_sort |
electron linac production of co-57 for gamma-chamber calibration |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2001 |
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http://dspace.nbuv.gov.ua/handle/123456789/79029 |
| citation_txt |
Electron linac production of Co-57 for gamma-chamber calibration /N.P. Dikiy, N.A. Dovbnya, O.A. Repikhov, I.N. Shlyakhov, V.L. Uvarov, Ja.N. Kravchenko // Вопросы атомной науки и техники. — 2001. — № 5. — С. 200-202. — Бібліогр.: 2 назв. — англ. |
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Вопросы атомной науки и техники |
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2025-07-06T03:08:52Z |
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| fulltext |
ELECTRON LINAC PRODUCTION OF CO-57 FOR
GAMMA-CHAMBER CALIBRATION
N.P. Dikiy, N.A. Dovbnya, O.A. Repikhov, I.N. Shlyakhov, V.L. Uvarov, Ja.N. Kravchenko1
National Science Center “Kharkov Institute of Physics and Technology”,
61108, Kharkov, Ukraine
uvarov@kipt.kharkov.ua
1 Kharkov Institute of Metrology,
61002, Kharkov, Ukraine
Gamma-chambers are widely used in medicine diagnostics to obtain an organ image investigated by means of the
scintigraphy method. A radionuclide Tc-99m which is accumulated in the organ and irradiates photons with the en-
ergy Eγ=140 keV is a carrier of the information. Ukraine manufactures gamma-chambers of own elaboration. A
γ-source with a photon energy of Tc-99m but with a larger half-life time is need for their plant calibration. The
Co-57 sources (Eγ=122 keV, T1/2=270 days) are the most eligible for this purpose. Their traditional technology is
based mainly on the reactor method and is accompanied by the large amount of the radioactive waste. The sources,
obtained in such a way, can not be regenerated after their decay. The R&D Complex “Accelerator” of the NSC
KIPT developed a new technology and manufactured the model – experimental batch of three Co-57 sources using
bremsstrahlung of the high-current electron linac. The Co-57 generation processes in the Ni-58 target were previ-
ously investigated by means of computer simulation. The optimum accelerator operation regime and a target geome-
try were thus determined. The obtained sources characteristics confirmed the computer analysis data. Each of them
is the plate of 28x28x1.5 mm and has the activity up to 2 mCi. The spectrum of the source measured with the Ge(Li)
detector satisfies all demands. The technology developed provides a production of sufficient amount of Co-57
sources practically without any waste, as well as, a possibility of their regeneration.
PACS number: 07.85.Fv
1 INTRODUCTION
One can produce a Co-57 isotope by means of nickel
irradiation with high-energy photons along two reaction
channels:
58Ni(γ,p)57Co (Q=-8.178 MeV, σmax=7.0 mb, E
γ max=20 MeV);
58Ni(γ,n) 57Ni → 57Co (Q=-12.204 MeV, σmax=23 mb, E
γ max=18 MeV);
Because the cross-sections of these reactions are
comparatively low there is need to solve a problem of
concentration of the powerful (≥10 kW) radiation flux
into the converter & target setup with ensuring corres-
ponding cooling of their elements for the Co-57 produc-
tion with an acceptable specific activity (≥10-3 Ci/g). So,
a choice of the target device geometry and its irradiation
regime is determined by optimization of such paramet-
ers as electron energy, thickness of the converter, target
and cooling water layers as well as a Co-57 generation
efficiency (i.e. the yield of the Co-57 nucleuses per one
accelerated electron).
2 COMPUTER SIMULATION
A 2D-model based on the GEANT code was elabor-
ated for investigation of the Co-57 generation in the nat-
ural Ni-target (that contains up to 68 % of Ni-58 iso-
tope) – [1]. The model considers a converter of a real
composition which includes an Al-casing and two
1.2 mm Ta-plates each cooling with water. The target is
considered as an infinite 10 mm thick plate.
The energy losses in each element of the setup were
calculated for 3 values of the electron energy (15, 20,
25 MeV) as well as a daily production of the Co-57 for
beam power as much as 1 kW (see Table 1).
Table 1. Results of computer simulation
Electron energy, MeV
10 15 20
Electron energy flux, kW 15 20 25
Co-57 activity, MBq/kW⋅ ⋅
beam⋅day
in reaction: 58Ni(γ,p)57Co
58Ni(γ,n) 57Ni → 57Co
1.26
0.86
9.68
28.57
20.86
65.53
Distribution of the energy
losses in the setup, W/kWbeam
Та-plates
water
Ni-target
703
73
77
601
75
135
508
70
200
An analysis of the table data shows that an increase
of the electron energy is accompanied both by essential
rise of the Co-57 yield and some leveling of distribution
of the radiation energy losses in the converter and target
elements. At the same time a further increase of the
electron energy is accompanied by appearance of the
undesirable (“background”) isotopes generation which
deteriorates a radiation spectrum of the final product.
3 EXPERIMENT
The target setup for experimental production of
Co-57 was assembled at the LU-20 Linac [2] – see
Fig. 1.
The aluminium casing 1 contains the cassette 4 (alu-
minium net) in which two tantalum plates 2 (converter)
are placed divided with 3 mm water layers as well as the
1.5x28x84, mm nickel plate (target). The latter consists
200
mailto:uvarov@kipt.kharkov.ua
of three lightly separated parts (28x28 mm). The casing
is supplied with two butt-end flanges which provide a
hermetic packing of the setup elements cooling with
running water under target irradiation.
During a Co-57 generation the accelerator was oper-
ating in the regime:
electron energy, MeV - 28
average beam current, µA - 530
pulse current, mA - 670
beam pulse repetition rate, Hz - 150
e-
e-
e-
A↑ A↑
water
A-A1
2
4
3
a) b)
Fig. 1. Target setup: a – lateral view, b – cross-sec-
tion.
A beam was continuously scanned also with 3 Hz
frequency in the vertical plane for uniform distribution
of the heat loading within the exit window of the accel-
erator and target elements. The radiation treatment of
the target lasted 100 hours. Then, after 20 days exposure
into a depository (for decay of the short-lived “back-
ground” isotopes) an experimental sample of the source
was placed into the specially designed shield block
(Fig. 2).
Fig. 2. Co-57 source into shield block with a set of
collimators.
4 METROLOGICAL INVESTIGATION
4.1. The gamma-chamber calibrator (later on “calib-
rator”) thus obtained consists of the radioactive Co-57
source placed into the shield block and supplied with
the 9°-collimator. The calibrator provides a radiation
field within certain region (“working region”) with the
necessary characteristics.
4.2. The purpose of the metrological investigation
was a determination of the next calibrator characterist-
ics:
- Co-57 source activity;
- radiation energy spectrum;
- relative distribution of the EDR within working region
of the calibrator;
- EDR distribution outside the working region.
4.3. Conditions and results of the measurements.
4.3.1. A measurement of the Co-57 source activity
was carried out by means of comparison of the pulse
rate count at the exit of the semiconductor spectrometer
supplied with the Ge(Li) detector in a certain energy
range including the Co-57 photopeak (122 keV) from an
investigated source and from the working standard
Co-57 source which has a known activity and is placed
at the same distance from the detector.
4.3.2. A measurement of the energy spectrum
(Fig. 3) was fulfilled using the same Ce(Li) detector.
4.3.3. A measurement of the EDR distribution
within a working region of the calibrator was carried out
by means of its placement at the distance 2300 mm from
the measurement plane and determination of the pulse
rate count at the exit of the TX 201AP semiconductor
detector. The latter has the characteristics:
sensor type - CdTe
size of monocrystal, mm - 5x5x2
bias voltage, V - 39
background noise, keV - ≤10
number of analyzer channels - 4096
maximum of measuring tract load, s-1 - 150
400 800 1200 1600 2000
Channals
1
10
100
1000
10000
N
122.1
136.5
511
661.6
810.8
846.8
1238
Co-57
Ε γ
Fig. 3. γ-radiation spectrum of the Co-57.
1
2
3
4
12
3
γ5
Fig. 4. Schematic diagram of measurement points of
the calibrator working region.
The detector TX 201 AP was placed in turn in each
of five measurement points of the working region
(Fig. 4). The exposure time in one point was 300 s. The
pulses with amplitude corresponding to the energy
range 60...140, keV and the pulses outside this range
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с. 201-202.
201
were calculated separately (see Table 2).
Table 2. Results of the calibrator working region
investigation
N of measur.
Point
Counts number
(60...140,keV)
Counts num-
ber, total
1 11600
2 11644
3 11612
4 11626
5 11658 24668
4.3.4. A distribution of the EDR outside the work-
ing region was carried out by means of placement of the
DRG 3-02 dosimeter in a measurement point. The ob-
tained data showed that the EDR value on a surface of
the shield block with closed lid and plugged collimator
- ≤360 µR/hr
at a distance 10 cm from the block
surface - ≤300 µR/hr
at a distance 40 cm from the block
surface - ≤30 µR/hr
4.3.5. An investigation of the EDR distribution
along the calibrator axes was carried out in the points
that are shown in Fig. 5.
100 cm 50 cm
123
200 cm300 cm
45
400 cm500 cm
6
Fig. 5. Scheme of the EDR measurement along the
calibrator axes.
Table 3. EDR value along the calibrator axis
N of measur. point EDR, µR/hr
1
2
3
4
5
6
2200
720
310
140
70
30
5 CONCLUSIONS
1. A technology for calibrator of the gamma-camera
production is elaborated. The technology is based
on using the bremssrahlung radiation of the high-
current electron accelerator.
2. The electron energy range 25...30 MeV seems to be
optimal for the Co-57 isotope generation in the Ni-
target.
3. The technology provides a Co-57 receipt as a
closed type radiation source with a possibility of its
multiple regeneration.
4. The calibrator produced under a new technology
has the next metrological parameters and character-
istics:
Co-57 source activity, mCi
-
2
energy of the main γ-radiation line, keV - 122
main co-product - Co-58
energy of the main co-product radiation
line, keV - 810
relative activity of the co-product
(normalized to activity of the main
Co-57 line), % - <1
distance from the source to the working
region plane, mm - 2300
exposure dose rate within the working
region, µR/hr - 300
main error of the source activity
measurement (P=0.95), % - ≤20
main error of the EDR measurement
within the working region (P=0.95), % - ≤15
The experimental prototype of the calibrator was
certificated in the Kharkov Institute of Metrology.
Work is supported by STCU under contract N 2185.
REFERENCES
1. N.P.Dikiy, A.N.Dovbnya, S.V.Maryokhin, V.L.U-
varov. On Efficiency of Medical & Biophysical
Isotopes Production Using Electron Accelerator //
Problems of Atomic Science and Technology. Is-
sue: Nucleatr-Physics Research (34). 1999, v. 3, р.
91-92.
2. A.N.Dovbnya et al. Electron Linacs Based Radia-
tion Facilities of Ukrainian National Science Center
“KIPT” // Bull. of Amer. Phys. Soc. 1997, v. 42,
# 3, p. 1391.
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