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Method and apparatus for the determination of electron density in a part volume of a body

  • US 3,961,186 A
  • Filed: 09/26/1974
  • Issued: 06/01/1976
  • Est. Priority Date: 10/09/1973
  • Status: Expired due to Term
First Claim
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1. A method for the determination of the electron density of desired small volumes, called the measuring volume, of a body comprising the steps of directing a first beam of ionizing radiation through said measuring volume to penetrate said volume in a first direction, said first beam having an intensity IO ;

  • measuring extra-corporally the intensity of the primary radiation and the intensity of scattered radiation in a second direction of the radiation of said first beam transmitted through said volume, said second direction forming an angle φ

    to said first direction;

    directing a second beam of ionizing radiation substantially of said intensity IO through said volume in said second direction;

    measuring extra-corporally the intensity of the primary radiation and the scattered radiation in said first direction of the radiation of said second beam transmitted through said volume in said second direction, employing such high energy radiation that the Compton effect will be the wholly dominant absorption phenomenon in said volume and in the radiation paths in said first and second direction, and that the change in the absorption cross-section from primary to secondary radiation caused by the Compton shift will be substantial; and

    employing the values of said measured intensities to calculate the electron density of said measuring volume in accordance with the formula;

    ##EQU30## where n = electron densityK = a calibration constantμ

    1 = the total linear attenuation coefficient for primary radiationμ

    2 = the total linear attenuation coefficient for Compton radiation "forwards"μ

    3 = the total linear attenuation coefficient for compton radiation "backwards"Ao = arbitrary expression for the power of the radiation sourceCc = measure of Compton radiationCd = measure of Compton radiationT1 = measure of Transmitted RadiationT2 = measure of Transmitted Radiation.

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