The fundamentals of 99mTc production cycle at electron accelerator
The report presents the results of investigations into physical and technological fundamentals of 99Mo/99mTc production with the use of bremsstrahlung of the electron accelerator. Викладені результати розробки фізичних і технологічних основ виробництва 99Мо/99mТс із використанням гальмівного випром...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2004 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2004
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| Цитувати: | The fundamentals of 99mTc production cycle at electron accelerator / N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov // Вопросы атомной науки и техники. — 2004. — № 1. — С. 168-171. — Бібліогр.: 8 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859707508911767552 |
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| author | Dikiy, N.P. Dovbnya, A.N. Uvarov, V.L. |
| author_facet | Dikiy, N.P. Dovbnya, A.N. Uvarov, V.L. |
| citation_txt | The fundamentals of 99mTc production cycle at electron accelerator / N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov // Вопросы атомной науки и техники. — 2004. — № 1. — С. 168-171. — Бібліогр.: 8 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The report presents the results of investigations into physical and technological fundamentals of 99Mo/99mTc production with the use of bremsstrahlung of the electron accelerator.
Викладені результати розробки фізичних і технологічних основ виробництва 99Мо/99mТс із використанням
гальмівного випромінювання прискорювача електронів.
Изложены результаты разработки физических и технологических основ производства 99Мо/99mТс с ис-
пользованием тормозного излучения ускорителя электронов.
|
| first_indexed | 2025-12-01T03:58:19Z |
| format | Article |
| fulltext |
BEAM APPLICATIONS
THE FUNDAMENTALS OF 99mTc PRODUCTION CYCLE
AT ELECTRON ACCELERATOR
N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov
National Science Center “Kharkov Institute of Physics and Technology”,
61108, Kharkov, Ukraine;
E-mail: uvarov@kipt.kharkov.ua
The report presents the results of investigations into physical and technological fundamentals of 99Mo/99mTc pro-
duction with the use of bremsstrahlung of the electron accelerator.
PACS: 06.60.Mr, 07.85.-m, 07.88+y, 81.30.Hd, 81.70.Jb
1. INTRODUCTION
99mTc (daughter nucleus of 99Mo) is the basic ra-
dionuclide used in the present-day medical diagnostics.
The main part of 99Mo is produced in nuclear reactors
with the use of the 235U fission reaction [1]. The special
features of 99Mo/99mTc generation at the electron acceler-
ator are determined by both a low production cross-sec-
tion for this isotope in photonuclear reactions
(~180 mbn) and a great transport length of high-energy
photons in substance. These special features set the re-
quirements on the systems of initial electron beam for-
mation and control, beam conversion into the
bremsstrahlung flux, on the target device and beam pa-
rameter monitoring in the process of irradiation, and
also on the system of radiochemical extraction of 99mTc
from the target. So, while the specific activity of fission-
produced 99Mo reaches 103 Ci/g [1], in the electron ac-
celerator case, this parameter makes ~0.1 Ci/g for the
natural molybdenum target and ~1 Ci/g for the target
enriched in the 100Mo isotope. This circumstance re-
stricts the choice of the procedure for 99mTc discharge by
high-selectivity methods (e.g., extraction, electrolysis,
etc.), and also calls for optimization of the technology at
all its stages.
2. PHYSICAL PRINCIPLES OF THE
PROCESS
2.1. Paper [2] has described the results of computer
simulation of 99Mo generation processes in liquid targets
based on alkaline solutions of natural Mo. The advan-
tages of these targets are the minimum number of proce-
dures involving the solution, and also the ease of orga-
nizing a loop-type cycle with target transportation be-
tween the accelerator and the setup for 99mTc extraction.
The disadvantages of the above targets lie in a low vol-
ume activity of 99Mo (as a result of which it is advisable
to realize this variant with the solution of isotopically
pure 100Mo as a basis), and also in instability of saturat-
ed solution as regards precipitation.
The analysis of the data obtained shows that the
highest yield of 99Mo in a solid natural molybdenum tar-
get, 14.4 g in mass, makes 5 Ci per day for the 40 MeV
beam of 10 kW power at a thickness of W converter of
1 mm and a thickness of converter-cooling water layer
of 3 mm (this being in agreement with the results of ref.
[3]). However, at these conditions a power of 3 kW is
released in the target, and this makes the target cooling
problematic. Here, as far as cooling is concerned, the
operating conditions with a cylindrical beam of 30 MeV
energy and up to 10 mm in diameter, appear real. In this
case, the production of 99Mo is reduced down to 2.75 Ci
per day, this however remaining acceptable as regards
both general and specific activity of the target.
2.2. The main task of the undertaken experimental
study of 99Mo generation processes at the electron accel-
erator was to determine the yield of this isotope per unit
charge of the beam as a function of accelerated electron
energy for targets of different geometry and phase com-
position.
The targets were irradiated at the accelerators EPOS
and KUT-20 [4].
2.2.1. For experimental studies into the regularities
of 99Mo production in water solutions a prototype of the
target device has been developed [5]. It consists of a
flowing water-cooled converter of bremsstrahlung and
four cylindrical vessels axially symmetric to the elec-
tron beam. The vessels were filled with a water solution
of Na2MoO4 with a Mo concentration of 142 mg/ml.
The experiments were performed at the EPOS accelera-
tor at dose accumulation conditions for different elec-
tron energies E0.
Table 1 lists the measured volume activity values for
the basic isotopes produced in 1 hour at an average
beam current of 10 µA for each mode of irradiation.
Table 1. Volume activity (A) of isotopes in target vessels
(Na2MoO4)
Е0,
MeV
№
vess
A, nCi/ml
90Mo 96Nb 99Mo 22Na 24Na
24
1 1.58 6.67 156.12 2.46 44.05
2 3.52 11.78 183.59 3.32 9.71
3 1.60 5.23 77.30 2.11 1.57
4 0.75 2.45 30.42 1.94 0.86
28
1 8.84 30.96 264.43 3.19 88.12
2 20.47 46.76 371.45 4.87 23.44
3 9.58 17.66 141.35 1.23 3.07
4 4.59 6.84 57.49 0.29 1.51
34
1 48.72 52.52 452.56 4.44 106.66
2 76.16 54.72 404.72 6.74 18.61
3 38.36 30.49 173.37 3.68 5.54
4 16.13 13.85 62.61 1.45 3.11
The reactions occurring only in the photonuclear
channel can be used to separate the contributions of dif-
ferent channels to the 99Mo generation. So, for the Na2-
MoO4 solution these are 23Na(γ,n)22Na (Q= 4.12− MeV)
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PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 1.
Series: Nuclear Physics Investigations (42), p.168-171.168
and 92Mo (γ,2n)90Mo (Q=-13.1 MeV).
The yield via the (n,γ) channel can be investigated
with the 23Na(n,γ)24Na reaction. The data obtained with
the help of the mentioned reactions on relative yields of
99Mo in (γ,n) and (n,γ) channels - Cγ and Cn (Cγ + Cn=1)
are given in the report [5].
The analysis of the resulting data has shown that the
solution of Mo, based on KOH, may appear more
promising as a liquid target. This solution provides a
higher concentration in Mo, gives less active wastes un-
der irradiation, and also permits later on practically a di-
rect separation of 99mTc by the extraction method.
2.2.2. Relying on the results of computer analysis, a
target device (Fig.1) was designed to investigate the
production of 99Mo in the solid phase.
The device is arranged immediately behind the flow-
ing water-cooled exit window (EW) of the accelerator.
Inside the casing S there are a converter C (4 tantalum
plates, each being 1 mm thick) and a target itself T in
the form of a truncated cone which is axially symmetric
to the electron beam.
Н2О
Н2О
Т
toe-
EW
S
MoO3
Mo
T2T1C
Fig. 1. Device for investigating 99Mo generation in solid
targets
Two versions of the target were made: one (T1) -
from metallic natural molybdenum, 30 g in mass; the
other (T2) - as an aluminum capsule which encloses two
foils from Mo and the MoO3 oxide, 50 g in mass. So,
the two targets had nearly the same content of natural
Mo. A thermocouple was placed inside each target to
measure the temperature during irradiation.
In these versions, the target was irradiated for 30
minutes at the accelerator KUT-20 at an electron energy
of 30 MeV, an average current of 7 µA. Then, the total
and specific activities of target elements were measured
with the help of the Ge(Li) detector (see Table 2). In the
process of irradiation, the steady-state temperature value
at the center of the MoO3 target made up 75°C at a cool-
ing water temperature of 36°C.
Table 2. Activity of solid-target elements
Target
element Т1
Т2
Мо foil
(front) МоО3
Мо foil
(back)
Acti-
vity,
МBq
8.249 0.142 5.70 0.065
3. BASIC SYSTEMS AND TREATMENT
PROCEDURES
The general scheme of the proposed 99Mo/99mTc pro-
duction technology is presented in Fig.2. It is designed
to accommodate the equipment within a single radia-
tion-protection zone. The radioactive elements of the
production cycle (target, irradiated structures, wastes,
etc.) remain within the zone, and only the final product
is removed from it in the form of sodium pertechnetate -
99mTc solution put into compact shipping containers and
having the permissible level of radiation.
The undertaken investigations have permitted us to
formulate a set of requirements to be met by the basic
systems of 99mTc production at the electron linac.
The accelerator has electron energy up to 40 MeV,
beam power no less than 10 kW, minimum transverse
dimensions of the beam (<10 mm) and its angular diver-
gence. The exit window of the accelerator at conditions
of direct (unscanned) beam must have an operating life
more than 1000 hours.
The accelerator monitoring system must provide a
continuous unperturbing monitoring of electron energy
(average value), beam current (pulsed value and average
value), and also of beam position within the exit win-
dow.
The target setup is designed in relation to the chosen
version of the target (liquid, metallic Mo or MoO3). In
any case, the cooling system of the complex must pro-
vide the removal of heat power from the bremsstrahlung
converter (no less than 3 kW) and from the target (no
less than 0.5 kW). Therefore, it is advisable to make the
converter rotating. The radiation durability of the setup
structures must be no less than 1⋅1010 Gy.
The sampling system is also determined by the cho-
sen variant of the target. In all cases, it is reasonable to
perform sampling and testing of the target at the initial
stage of its irradiation. This is determined by the neces-
sity of measuring the rate of generation of the main iso-
topic product (99Mo) and by-products (for correcting, if
necessary, the conditions of target processing), and by
the possibility of safe handling the target.
In the liquid target case, the sampling procedure
consists in taking a 1...2 ml sample of irradiated solution
with an activity up to 1 µCi.
For the metallic Mo or MoO3 target, a sample, i.e.,
Mo foil, is placed at the exit of the target device, coaxi-
ally with the target. The accelerator is switched on to be
operated in the mode of target treatment, and the sample
is activated up to ≤1 µCi. Then, the sample is forwarded
to the gamma-spectrometer. To optimize the target irra-
diation conditions and target adjustment with respect to
the flow of braking photons, the method of measuring
the surface activity distribution of the foil by means of a
collimated CdZnTe radiometer has appeared to be rather
efficient.
The irradiated target transport system provides a re-
mote discharge of the target (the equivalent dose rate
(EDR) on the surface makes > 10 Sv/h) into a container,
transportation of the container to the radiochemical lab-
oratory, a remote-controlled withdrawal of the target
and its transfer into the shielding box for further treat-
ment.
The system of target processing is determined by the
form of the target. In the realistic version of the target
based on natural molybdenum with a comparatively low
activity (up to 3 Ci), the efficient separation of 99mTc is
provided by the method of multiple extraction of 100Mo
containing water solution by one and the same extrac-
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 1.
Series: Nuclear Physics Investigations (42), p.168-171.169
tant (methyl ethyl ketone) volume [6]. The final product
is the solution of sodium pertechnetate-99mTc of standard
activity, which is packed into flasks and undergoes ster-
ilization.
If the isotopically enriched 100MoO3 target is used,
the radiochemical facility can readily be supplemented
with a circuit for reduction of trioxide from the solution
at the end of the 5-day cycle of 99mTc extraction for the
repeat production of 99Mo at an accelerator.
The isotope product quality control system involves
a set of measuring devices and methods for determining
the correspondence of the product to the Pharmacopoeia
Regulations (PhR).
The radioactive wastes (RAW) handling system pro-
vides a stock-piling of wastes in temporary storages,
and also a periodic control of RAW activity.
The final-product transportation system includes
portable shipping containers, which accommodate flasks
with the solution of sodium pertechnetate-99mTc, and
also specially equipped transport means for the delivery
of containers to clinics.
The radiation dosimetry system embraces all techno-
logical procedures accompanied by the action of radia-
tion on personnel. The requirements on the system and
admissible levels of exposure are described in Radiation
Safety Standards.
4. CONCLUSION
The undertaken investigations have resulted in the
elaboration of the fundamentals of a soft technology of
99mTc production for nuclear medicine with the use of
the electron accelerator. The proposed process is fully
compatible with the technologies in service today, based
on the 98Mo(n,γ)99Mo reaction [6,7], as regards the pro-
cedures of radiochemical extraction of 99mTc, prepara-
tion of the solution of sodium pertechnetate-99mTc, pack-
ing and sterilization, control of product quality and de-
livery to the customers. These circumstances facilitate
the procedure of new technology certification.
R a d i a t i o n d o s i m e t r y
Monitoring of
electron beam
parameters
on the target
Monitoring
of target
parameters
during
irradiation
Monitoring
of isotope
product
generation
conditions
Production of 99mТс:
extraction, packing
and sterilisation
of products
Sampling
system
Target recovery
Monitoring
of products
to comply with
the PhR
Monitoring
of quantity
and activity
of wastes
Radioactive wastes
handling system
Electron
accelerator
Target
complex
Transport
system
Target
processing
system
Product quality
control system
System of product
shipping to the
customer
Fig.2. Functional block diagram of 99mTc production at the electron accelerator
The use of the target enriched in the 100Mo isotope
appears most efficient, both economically and ecologi-
cally. For example, in the case of >95% enrichment, the
yield of 99Mo increases by order of magnitude as com-
pared with the target of natural composition. The activi-
ty of liquid RAW produced in one technological cycle is
reduced to the same extent. Though 100Mo is expensive
(up to $5000 for 1 gram), a single purchase of 30 grams
of the isotope provides a long-standing production of
99mTc. Really, in one cycle of irradiation, no more than
10-6 nuclei of 100Mo transmute into 99Mo, and after ex-
traction of 99mTc, 100MoO3 can be easily reduced from
the water phase to be used for the repeat irradiation.
The use of reactor Mo accumulated in the wastes
from spent fuel processing [8] is less expensive. The
concentration of 100Mo in this case is 28% (9.6% in the
natural Mo), i.e., the efficiency of the process is 3 times
increased.
5. ACKNOWLEDGEMENTS
The authors express their gratitude to L.V. Yeran for
computer simulation of the processes of 99Mo genera-
tion, to V.A. Shevchenko for the help in preparing and
performing experiments, and to Yu.V. Lyashko for the
gamma-spectrometric analysis of samples.
The work has been supported by the STCU under
Contract # 2185.
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// Problems of Atomic Science and Technology.
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1999, № 3, р. 91-92.
3. R.G. Bennett et al. A System of 99mTc Production
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5. N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov. Electron
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6. A.I. Komov, V.S. Skuridin, A.G. Rybasov,
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7. A.V. Yegorov, M.P. Zykov, G.V. Korpusov et al.
Production of 99mTc on the Centralized Generator in
St. Petersburg // J.Nucl. Biol. Med. 1994, v. 38,
№ 3, p. 399-402.
8. S.A. Bartenev, M.P. Zykov, V.N. Romanovsky et
al. Production of Molybdenum-99 & Technetium-
99m from Molybdenum-100 // Abstr. of 9-th Na-
tional Conf. of Application of Charged Particle Ac-
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1998, St.-Petersburg, Russian), p.112 (in Russian).
ОСНОВЫ ТЕХНОЛОГИЧЕСКОГО ЦИКЛА ПО ПРОИЗВОДСТВУ 99mТс НА УСКОРИТЕЛЕ
ЭЛЕКТРОНОВ
Н.П. Дикий, А.Н. Довбня, В.Л. Уваров
Изложены результаты разработки физических и технологических основ производства 99Мо/99mТс с ис-
пользованием тормозного излучения ускорителя электронов.
ОСНОВИ ТЕХНОЛОГІЧНОГО ЦИКЛУ ПО ВИРОБНИЦТВУ 99mТс НА ПРИСКОРЮВАЧІ
ЕЛЕКТРОНІВ
М.П. Дикий, А.М. Довбня, В.Л. Уваров
Викладені результати розробки фізичних і технологічних основ виробництва 99Мо/99mТс із використанням
гальмівного випромінювання прискорювача електронів.
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 1.
Series: Nuclear Physics Investigations (42), p.168-171.171
N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov
National Science Center “Kharkov Institute of Physics and Technology”,
61108, Kharkov, Ukraine;
E-mail: uvarov@kipt.kharkov.ua
1. INTRODUCTION
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-79063 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-01T03:58:19Z |
| publishDate | 2004 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Dikiy, N.P. Dovbnya, A.N. Uvarov, V.L. 2015-03-25T19:26:33Z 2015-03-25T19:26:33Z 2004 The fundamentals of 99mTc production cycle at electron accelerator / N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov // Вопросы атомной науки и техники. — 2004. — № 1. — С. 168-171. — Бібліогр.: 8 назв. — англ. 1562-6016 PACS: 06.60.Mr, 07.85.-m, 07.88+y, 81.30.Hd, 81.70.Jb https://nasplib.isofts.kiev.ua/handle/123456789/79063 The report presents the results of investigations into physical and technological fundamentals of 99Mo/99mTc production with the use of bremsstrahlung of the electron accelerator. Викладені результати розробки фізичних і технологічних основ виробництва 99Мо/99mТс із використанням гальмівного випромінювання прискорювача електронів. Изложены результаты разработки физических и технологических основ производства 99Мо/99mТс с ис- пользованием тормозного излучения ускорителя электронов. The authors express their gratitude to L.V. Yeran for computer simulation of the processes of 99Mo generation, to V.A. Shevchenko for the help in preparing and performing experiments, and to Yu.V. Lyashko for the gamma-spectrometric analysis of samples. The work has been supported by the STCU under Contract # 2185. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Применение ускоренных пучков The fundamentals of 99mTc production cycle at electron accelerator Основи технологічного циклу по виробництву 99mТс на прискорювачі електронів Основы технологического цикла по производству 99mТс на ускорителе электронов Article published earlier |
| spellingShingle | The fundamentals of 99mTc production cycle at electron accelerator Dikiy, N.P. Dovbnya, A.N. Uvarov, V.L. Применение ускоренных пучков |
| title | The fundamentals of 99mTc production cycle at electron accelerator |
| title_alt | Основи технологічного циклу по виробництву 99mТс на прискорювачі електронів Основы технологического цикла по производству 99mТс на ускорителе электронов |
| title_full | The fundamentals of 99mTc production cycle at electron accelerator |
| title_fullStr | The fundamentals of 99mTc production cycle at electron accelerator |
| title_full_unstemmed | The fundamentals of 99mTc production cycle at electron accelerator |
| title_short | The fundamentals of 99mTc production cycle at electron accelerator |
| title_sort | fundamentals of 99mtc production cycle at electron accelerator |
| topic | Применение ускоренных пучков |
| topic_facet | Применение ускоренных пучков |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79063 |
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