716
M. Dohlus et al.
continuous maintenance. Each year 30 millions diagnostic studies, 80% of all
medical scans that use radioisotopes, are made with Technetium-99m (6 h half-life)
from a Molibdenum-99 generator (66 h of half-life).
The shortage of Molybdenum-99 stimulated several initiatives for finding alternative solutions and the use accelerator was considered for the production of
either Molybdenum-99 or directly Technetium-99m. If, from one side, a single
accelerator facility is unable to compete in production with large reactors, on the
other side it allows a better distributed production with advantages for the logistics,
the possibility of producing directly technetium-99m for locally distributed end
users, and undisputable environmental benefits. The accelerators considered for
different productions processes are electrostatic accelerators, electron linacs, and
cyclotrons.
Two Canadian initiatives were established to produce Technetium-99m trough
the reactions 100 Mo(p,2n) 99m Tc [62]. The projects use existing cyclotrons available
for positron emission tomography (PET) from General Electric (130 μA, 16.5 MeV)
and Advance Cyclotron Systems, Inc. (300 μA, 19 MeV) and the productions
should start in 2017. The clinical trial which compared reactor- and cyclotronproduced Technetium-99m was concluded in 2017 receiving the approval from
Health Canada.
Some project plan to substitute reactor-generated neutrons with acceleratorgenerated neutrons. To reach the capabilities of a reactor production, the neutron rate
should exceed 10 14 neutrons per second. The concept developed by the company
Shine is based on the fusion of deuteron and tritium for producing neutrons (and
helium). The electrostatic accelerated deuterons (300 keV, 60 mA) are directed
toward a tritium target. The resulting neutrons (5·10 13 neutrons per second) cross
a natural uranium target for neutron multiplication and irradiate a low enriched
uranium target producing, among other fission products, Molybdenum-99. The first
facility is in construction phase.
The company NorthStar is developing a facility for the production of
Molybdemum-99 from photo-nuclear reactions 100 Mo(γ,n) 99 Mo using electron
linacs. Two accelerators (40 MeV, 3 mA each) direct the electron beams from
opposite sides to a Molybdenum-100 target where the bremsstrahlung photons are
created. The production is expected to start in 2017 [63].
Another project linked to TRIUMF is the development of a high-current electron
linac (50 MeV, 100 mA) for the generation of photons that, directed to a target of
Uranium-238 produce Molybdenum-100 from photo-fission.
Electron linacs for the generation of neutrons are foreseen in different project
from Shine (35 MeV, 0.6 mA), and Niowave (superconductive 40 MeV, 2.5 mA).
The generated neutrons irradiate a target containing a solution of depleted uranium.
Several other ways of using accelerators for production of Molibdemun-100
or Technetium-99m have been proposed and are still under study and development [64].
M. Dohlus et al.
continuous maintenance. Each year 30 millions diagnostic studies, 80% of all
medical scans that use radioisotopes, are made with Technetium-99m (6 h half-life)
from a Molibdenum-99 generator (66 h of half-life).
The shortage of Molybdenum-99 stimulated several initiatives for finding alternative solutions and the use accelerator was considered for the production of
either Molybdenum-99 or directly Technetium-99m. If, from one side, a single
accelerator facility is unable to compete in production with large reactors, on the
other side it allows a better distributed production with advantages for the logistics,
the possibility of producing directly technetium-99m for locally distributed end
users, and undisputable environmental benefits. The accelerators considered for
different productions processes are electrostatic accelerators, electron linacs, and
cyclotrons.
Two Canadian initiatives were established to produce Technetium-99m trough
the reactions 100 Mo(p,2n) 99m Tc [62]. The projects use existing cyclotrons available
for positron emission tomography (PET) from General Electric (130 μA, 16.5 MeV)
and Advance Cyclotron Systems, Inc. (300 μA, 19 MeV) and the productions
should start in 2017. The clinical trial which compared reactor- and cyclotronproduced Technetium-99m was concluded in 2017 receiving the approval from
Health Canada.
Some project plan to substitute reactor-generated neutrons with acceleratorgenerated neutrons. To reach the capabilities of a reactor production, the neutron rate
should exceed 10 14 neutrons per second. The concept developed by the company
Shine is based on the fusion of deuteron and tritium for producing neutrons (and
helium). The electrostatic accelerated deuterons (300 keV, 60 mA) are directed
toward a tritium target. The resulting neutrons (5·10 13 neutrons per second) cross
a natural uranium target for neutron multiplication and irradiate a low enriched
uranium target producing, among other fission products, Molybdenum-99. The first
facility is in construction phase.
The company NorthStar is developing a facility for the production of
Molybdemum-99 from photo-nuclear reactions 100 Mo(γ,n) 99 Mo using electron
linacs. Two accelerators (40 MeV, 3 mA each) direct the electron beams from
opposite sides to a Molybdenum-100 target where the bremsstrahlung photons are
created. The production is expected to start in 2017 [63].
Another project linked to TRIUMF is the development of a high-current electron
linac (50 MeV, 100 mA) for the generation of photons that, directed to a target of
Uranium-238 produce Molybdenum-100 from photo-fission.
Electron linacs for the generation of neutrons are foreseen in different project
from Shine (35 MeV, 0.6 mA), and Niowave (superconductive 40 MeV, 2.5 mA).
The generated neutrons irradiate a target containing a solution of depleted uranium.
Several other ways of using accelerators for production of Molibdemun-100
or Technetium-99m have been proposed and are still under study and development [64].