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Fast Scintillators

#3333


Development of High Speed Scintillators for Medical Tomography

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials

Status
3 Approved without Funding

Registration date
28.07.2005

Leading Institute
Vavilov State Optical Institute (GOI) / Research and Technological Institute of Optical Materials, Russia, St Petersburg

Supporting institutes

  • VNIIKhT (Chemical Technology), Russia, Moscow

Collaborators

  • Crystal GmbH, Germany, Berlin\nVITCON Projectconsult GmbH, Germany, Jena

Project summary

The environmentally appropriate and energy-conservation technology of “high speed” scintillators, destined for medical tomography will be developed in the project. The vapor phase method of growth will be put in a basis of technology obtaining of lead fluoride and zinc fluoride polycrystals and also zinc selenide doped by tellurium. These scintillators are perspective for application in tomography, but the existing technology does not provide necessary crystal quality and acceptable cost of crystals.

At present time ZnSe: Te crystals are grown from liquid melt (1520оC) at high pressure of inert gas and at doping by Zn, Se, and Te (O) during of growth or annealing process. Such technology is difficult enough and causes high cost of a product.

It is necessary to note also the crystals obtained by such method have an insufficient transparency; therefore developers do not recommend using crystals with thickness more than 3-4 mm.

The crystals of PbF2 are grown from liquid melt at fluorination with application of toxic gaseous reagents.

There is an experience of obtaining of polycrystalline optical materials from vapor phase in our institute FGUP NITIOM of VNC “S.I. Vavilov GOI”. Optical quality of a material in this case is provided not worse than in case of single crystal, and the high temperature and application of toxic gaseous reagents is not required. It is possible to enter doping additives for increase of scintillation efficiency which do not manage to be entered at crystallization from melt.

In the project it is offered to use vapor-phase process for obtaining of polycrystalline zinc selenide doped by tellurium and also lead and zinc fluorides which are perspective for making of high speed scintillators.

In this project it is supposed to investigate:

  • The technological scheme of obtaining of initial raw material with necessary purity.
  • The kinetics of crystallization of zinc selenide doped by tellurium, and also lead and zinc fluorides from a vapor phase.
  • Process of purifying of lead and zinc fluorides from oxygen impurity during vapor phase growth.
  • Influence of technological parameters on structure of the polycrystals which have been grown from vapor phase.
  • Doping conditions of zinc selenide by tellurium.
  • Optical properties and scintillation characteristics of polycrystalline samples.

On the basis of the obtained data the technology of high speed polycrystalline scintillators destined for medical tomography will be developed.

The equipment for obtaining of the specified materials will be developed and scintillator samples for medical tomography will be submitted upon termination of the project.


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