Function to represent the variation of central axis tissue air ratio with two dimensions of 60Co rectangular fields.

Tissue air ratios (TAR) for rectangular 60Co fields depend on the two dimensions of the field. Functions which make use of the two dimensions of the field as parameters have been derived. The accuracy of fit such functions can give to the standard tissue air ratio data have been studied and discussed.

Shaping of isodose curves in intracavitary irradiation using the afterloading method. A feasibility study involving mathematical simulation.

The possibility of adjusting the irradiation scheme to shape the isodose curve around an intracavitary source arrangement was studied mathematically. The total number of millicurie hours of irradiation for each source position was derived by a linear programming approach, taking into account the shape of the tumor in three different cases. The practical isodose curves obtainable with the source arrangement chosen were compared with the shape desired.

Radiation hazards from 241Am sources used in thyroid studies.

The neutron and gamma photon doses corresponding to the neck and eye level from an 241AmO2 source used in thyroid studies have been theoretically estimated. The radiation hazard to the patient is found to be not significant.

An estimate of the 60Co gamma attenuation in the small phantom enployed in the definition of tissue air ratio.

Tissue air ratio definition employs a concept of dose at the centre of a small mass of tissues that is suspended in air and is just large enough to give electronic equilibrium at its own centre. When the dose at the centre of the said small mass of tissue is to be derived from a knowledge of exposure in free air at the same point, the attenuation in the small mass of tissue should be taken into account. This attenuation for 1250 keV photons has been evaluated through a theroretical model and the attenuation factor is estimated to be 0.

The estimation of N-nitrosamines in tropical regions by reversed-phase paper and thin-layer chromatography.

A simple and convenient procedure based on reversed-phase paper and thin-layer chromatography is reported for the detection and estimation of N-nitrosamines in food products, particularly cured meat. The method can easily be applied in tropical regions when plenty of sunshine is available. It is particularly useful in food-testing laboratories where sophisticated analysical instruments such as the gas chromatograph, mass spectrometer, etc.

Manifestation of anaphylaxis to egg albumen in the lizard, Calotes versicolor.

Anaphylaxis was induced in the lizard, Calotes versicolor by egg albumen. The symptoms were similar to those found in other species. The maximum mortality occurred 14 days after sensitization and the reaction was specific.

Chloramphenicol metabolism in children with protein-calorie malnutrition.

The plasma levels and urinary excretion of chloramphenicol was studied in ten malnourished children and four normal children after oral administration of a single dose of 25 mg/kg body weight. Plasma peak levels were achieved 2-4 hours later and were 1.5 or 2 times higher in malnourished children compared to the normal.

Skin dose with cones and diaphragms in 137Cs teletherapy - a study using lithium borate thermoluminescent dosimeters.

Beam definition in 137Cs teletherapy is done either by use of cones for specified SSDs or by means of adjustable diaphragms. Using lithium borate thermoluminescent dosimeters, the skin dose was studied for conditions of the bare cone without any electron filter, the cone with an affixed perspex cup for cutting off the electrons, the cone with an affixed copper plate filter at its face. It was observed that of the above three arrangements, the case employing the copper filter gave the minimum skin dose.

Effect of prostaglandin F2 alpha and hypertonic saline on the placental function during midtrimester abortion.

Changes in placental function during the induction of midtrimester abortion by prostaglandin F2 alpha and hypertonic saline were investigated. Serial estimations of human placental lactogen (HPL) and cystine aminopeptidase (CAP) were carried out in 17 subjects. There was a significant (P smaller than 0.