IN VIVO MEASUREMENT OF NUCLIDES EMITTING SOFT PENETRATING RADIATIONS.
Abstract
This report presents the results of experiments utilizing a 1 mm thick CsI(Tl) crystal in conjunction with a NaI(Tl) crystal anti-coincidence system for the quantitative in vivo assessment of body burdens of low energy photon emitters such as 239Pu, 90Sr, 210Pb and natural and enriched uranium. Measurements done to obtain optimum crystal thickness have shown a thickness of 1 mm to be a practical compromise for all three nuclides. The use of this thin crystal in conjunction with a NaI(Tl) crystal anti-coincidence system using rise-time discrimination is effective in reducing background in the low energy region by approximately 60%, and the Compton continuum of 137Cs by as much as 70%. The use of this system has led to the development of a prototype, portable in vivo counter with an 8 inch diameter by 1 mm thick CsI(Tl) detection crystal and an 8 inch diameter by 2 inch thick NaI(Tl) anti-coincidence crystal. The crystals are mounted in a moveable rig which allows movement in the X, Y, and Z planes. The entire rig, including electronic apparatus - without a multichannel analyzer - weighs on the order of 200 lbs. Calibration measurements performed with the large crystal have shown minimum significant measurable levels of activity (MSA's) which indicate that body burdens, more particularly lung burdens, may be measured at a fraction of the Maximum Permissible Body Burden without the use of a steel room. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 13, 1969
- Accession Number
- AD0690243
Entities
People
- G. R. Laurer
- Merril Eisenbud
Organizations
- New York University