THE EFFECT OF EXPOSURE GEOMETRY AND BEAM SPECTRUM ON DEPTH-DOSE PATTERNS FOR PENETRATING IONIZING RADIATION IN LARGE MAMMALS AND MAN
Presented as part of a symposium at the Radiation Society Meetings, Chicago, Illinois, May 17 to 19 1956. patterns for a phantom approximating the size of man are presented for a variety of exposure conditions including unilateral, bilateral, multilateral, cross fire, rotational, and 4 pi techniques; initial gamma radiation from nuclear bombs, and gamma radiation from radioactive fallout. Since monitored readings as well as calculations for nuclear effects involve of necessity the air dose, and most large-animal radiobiological data are reported similarly, tissue doses in the phantom are given here in terms of the entrance dose as measured in free air. The marked difference in dose absorbed in tissue for a given air dose, as usually expressed, is pointed out, as are the marked differences in the degree of homogeneity of dose through the tissues, under the lethality data are tabulated, and the widely- varying degrees of effect noted for the same air dose, under the several conditions used, are compared with those predicted from geometrical considerations. Expressing the degree of exposure as midline tissue dose, instead of entrance air dose, results in a better correlation of dose and effect for some, but not all of the geometrical situations considered. The integrated tissue dose expressed as gram-roentgens is shown to be an unsatisfactory concept for the correlation of biological data for the different geometrical situations discussed. The additional complicating factors of beam energy and spectrum on the determination of the biological effect are discussed. 41 references. (auth)
- Research Organization:
- Naval Radiological Defense Lab., San Francisco; Naval Medical Research Inst., Bethesda, Md.; Brookhaven National Lab., Upton, N.Y.
- NSA Number:
- NSA-13-005225
- OSTI ID:
- 4276373
- Report Number(s):
- NM-62-02-00.01.02; AD-200455
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-59
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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