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Chemical Vapor Deposition Films for Dosimetry

#3950


Development and Production of Multichannel Measuring System with CVD-Films for Clinical Dosimetry

Tech Area / Field

  • MED-DID/Diagnostics & Devices/Medicine
  • INS-DET/Detection Devices/Instrumentation
  • INS-MEA/Measuring Instruments/Instrumentation

Status
3 Approved without Funding

Registration date
03.02.2009

Leading Institute
Research Institute of Scientific Instruments, Russia, Moscow reg., Lytkarino

Supporting institutes

  • NIIIT (Pulse Techniques), Russia, Moscow\nCentral Clinical Hospital of the General Management Department of the President of Russian Federation, Russia, Moscow\nITEF (ITEP), Russia, Moscow

Collaborators

  • Universita degli Studi di Salerno / Dipartimento di Fisica "E.R. Caianiello", Italy, Salerno\nDiamond Detectors LTD, UK, Dors, Poole

Project summary

In Russia, practically there are no multichannel measuring systems (MMS) for the fast daily monitoring and adjustment of radiation therapeutic beams. Also now it is very difficult to check implementation of complicated plans of irradiation (using dynamic wedges, multilobes collimators, and different kinds of radiation). Dosimetry of proton (ionic) beams is at a low level. Recently, foreign MMSs of a matrix type on the basis of air ionization chambers have appeared. However, they have some lacks: dependence of indications on temperature and air pressure. Besides, these MMSs do not allow dosimetry of intensive proton therapeutic beams with the spatial resolution less than 1 mm to be carried out. The outcome of recently completed ISTC project # 822 has shown an opportunity of MMS creation on the basis of cheap natural diamonds (in comparison with detectors of the Company PTW-FREIBURG). It is offered to develop the MMS of a matrix type on the basis of cheaper CVD-films (even in comparison with ionization chambers) for decision of tasks to be achieved. CVD-chemical vapor deposited – synthetic diamonds with low pressure. The attempts of foreign investigators to use CVD-films for clinical dosimetry have not resulted in occurrence of a practical device because of influence of polarization, which they could not overcome. The technical decisions, which have been patented under performance of Project # 822, allow overcoming the influence of diamond polarization. Quality of a significant part of natural diamonds used in a model MMS developed under Project # 822 was lower than the quality of CVD-films used by foreign investigators. CVD-films allow matrix structures to be created with the spatial resolution less than 1 mm with use of photolithographic technology that is important for the control of narrow proton beams under irradiation of eye patients.

The purpose of the proposed project is to develop and create models of the MMSs on the basis of CVD-films for clinical dosimetry of photon, electron and proton (ionic) beams with the accuracy required for medical practice.

A principle of construction of an MMS electronic part (with 30 channels) and basic algorithms of mathematical software (MS) were developed in the previous project. Principles of MMS graduation for photon and electron beams with the necessary accuracy have been also developed. It is necessary to perform the following works:

  1. To obtain and investigate samples of CVD-films from foreign companies and also new domestic samples for photon and electron dosimetry.
  2. To make a matrix unit of detectors from suitable samples with 256 channels for clinical photon and electron dosimetry.
  3. To develop and manufacture a breadboard model of the appropriate electronic recorder.
  4. To develop MS.
  5. To investigate techniques for manufacturing detectors on the basis of CVD-films for dosimetry of narrow proton (ionic) beams.
  6. To make a matrix unit of detectors with 128 channels for proton (ionic) dosimetry with the spatial resolution of about 1 mm.
  7. To develop methods for the MMS graduation for proton (ionic) dosimetry.
  8. To investigate the MMS in the appropriate radiation therapeutic beams of operating installations.
  9. To develop techniques for application of the MMS to clinical practice.

Highly skilled scientists and engineers will participate in development of the Project. The published papers as well as the results of previous ISTC project #822 prove their qualification. Work under the project and realization of its results will allow weapon scientists and engineers to go from military activity to civil one. There is a real opportunity to develop a MMS prototype and to use the project results for commercial goals.

As a result of the project, the breadboards of the matrix type MMSs for photon, electron, and proton (ionic) therapeutic beams will be designed, manufactured and tested. Techniques for graduation and the MS will be developed. Measurements of profiles of the appropriate therapeutic beams with each second updating will be carried out. Techniques for clinical application of the MMS will be developed.

Realization of the project will allow considerable expediting the adjustment of therapeutic beams for specific layout of irradiation thereby reducing the price of patients’ irradiation. The accuracy of doze release will be increased, especially on edges of beams that will allow reducing irradiation of healthy fabrics.

The consent (informal) to participate in the present project has been given by Dr. Indera K. Daftary from the University of California, USA, a collaborator of ISTC project # 822. There is an arrangement concerning a demonstration of the developed technologies on therapeutic radiation accelerates of the University of California (if customs questions of equipment import and export are settled).


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