Search PubMed⌕ Search

Biomedical subjects

D Greene

Publications and source records attributed to D Greene.

At least 91 records · Page 5Linked to original sources
PubMed1977

Re-irradiation of rat tails to necrosis at six months after treatment with a "tolerance" dose of x rays or neutrons.

Rat tails were re-irradiated to necrosis levels at about six months after various fractionated treatments with 290 kV X rays or 14 MeV neutrons. The X ray dose required to produce necrosis in half of a group of tails (ND50), which had been heavily X-irradiated six months before, was 91+/-4% of the ND50 for aged controls. After prior neutron-irradiation, however, this value was 87+/-4% (neutrons in second treatment) or 75+/-5% (X rays in second course). The "effective" oxygenation of mouse tails at this time after X-irradiation was similar to that of controls; thus these percentage dose values indicate the remarkable tolerance of this organized tissue to a second course of X-irradiation, and the presence of more residual injury in neutron-irradiated tissues.

Animals↗
PubMed1976

Addition of neutron and gamma-ray fractions for intestinal damage.

The microcolony assay technique has been used to test the validty of summing equivalent doses per fraction of 14 MeV neutrons and gamma rays for mouse intestinal damage. For a 4-daily fraction schedule, in which the first one or two fractions are given as neutrons and the remainder as gamma rays, combined dose fractions calculated from a 4-fraction schedule of either radiation type alone produce the same level of damage within the limits of accuracy of the experiment.

Animals↗
PubMed1976

Tolerance of rodent tails to necrosis after "daily" fractionated X rays or D-T neutrons.

The rat tail has been used as a model system to study the necrosis of an organized tissue following fractionated doses of collimated D-T neutrons or 290 kV X rays. RBE values for tail tolerance - 10 per cent of tails necrosing after the early skin reactions - rise from about 1-7 (single doses) to about 3-1 (16 fractions in 22 days). Neutron tolerance doses are almost independent of fractionation from 2 to 16 fractions. The tissues at risk are shown to be rather hypoxic. Early skin reaction levels can be used to predict the fraction of tails that will necrose. Early peak reactions for a given fraction of necrotic tails were slightly higher for neutrons than for X rays, and this difference was consistent for all the dose fractionation schedules employed.

Animals↗
PubMed1975

The use of a calorimeter for neutron dosimetry.

The dose given to a polythene energy absorber in the radiation field from a 14 MeV neutron generator has been measured calorimetrically. The calorimeter was calibrated by giving the energy absorber a known dose of gamma-rays. The dose measured in this way was compared with that determined with a polythene-ethylene ionization chamber, and the two results agreed to better than 1%, though the estimated uncertainties on the calorimeter and ionization chamber results were each about 4%. This result can be used to determine a value of the ratio Wn/We, for 14 MeV neutrons in ethylene, where Wn is the W value for the charged particles generated in the neutron field in ethylene, and We is the W value for electrons in the same gas. The measured value of Wn/We was found to be 1.07 plus or minus 3.9%. The significance of the 'thermal defect' in polythene is discussed.

Calorimetry↗
PubMed1975

Ultrasonic diagnosis of hypernephroma extending into the inferior vena cava.

Extension of hypernephroma into the inferior vena cava was demonstrated by ultrasound. When a solid renal lesion is encountered, it is suggested that the inferior vena cava be scanned. The possible significance of gray scale scanning as a more precise diagnostic tool and its use in tumor staging are discussed.

Adenocarcinoma↗