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Biomedical subjects

A Nagaratnam

Publications and source records attributed to A Nagaratnam.

16 recordsLinked to original sources
PubMed1995

Formulation of the reference Indian adult: anatomic and physiologic data.

Data on heights and weights of Indian males and females of various ages are presented. The weights of specific organs obtained from post-mortem records of accident cases of Indian adults and children are also presented to provide some inputs towards formulation of an Indian Reference Man for radiation protection purposes. An intercomparison of the present data with the data available from other sources including those for ICRP Reference Man, Woman, and Child has been made. The daily intakes of air, water, and dietary constituents of an average Indian adult are also given.

Adolescent↗
PubMed1992

Organ weights in autopsy cases from an urban apex hospital.

The available limited anatomical and physiological data have been compiled for Indian adult as a part of ongoing efforts in the country to formulate an Indian Reference Man for radiation protection purposes. The parameters included weight, height, body surface area, weight of various organs (brain, heart, kidney, lung, liver etc.), total body water, extra-cellular water, blood volume, specific gravity, total lung capacity, vital capacity etc. The data have been drawn from post-mortem studies (566 males and 185 females) and other data from published work on 433 healthy male and 137 female volunteers. Data gaps have been filled by the method of pooling wherever necessary. This paper presents the intercomparison of the present data with the data available from other sources. The data from various Indian sources indicate a similar trend. However, a significant difference (P less than 0.01) was observed in organ weights and total body weights, in comparison to the Bhabha Atomic Research Centre (BARC) values. The present data are not comprehensive enough to suggest definitive norms of the Indian Reference Man.

Adult↗
PubMed1988

Radiation dose to various age groups from radionuclide impurities in 99mTc-pertechnetate (fission product 99Mo generator) radiopharmaceutical preparations.

Radionuclide impurities of radiopharmaceuticals do not provide any diagnostic information, but contribute to the radiation dose to the patient. For 99mTc, even small amounts of long lived radionuclide impurities may contribute significantly to the dose from 99mTc itself. In this preliminary study, estimates have been made for the radiation dose to specific organs and for the effective dose equivalent from impurities in 99mTc-sodium pertechnetate prepared from fission product 99Mo. In addition to 99Mo, 131I, 103Ru, 89Sr and 90Sr at maximum permissible levels as stipulated in the European Pharmacopoeia, 110mAg and 239Pu were taken as representative nuclides for beta-gamma emitters and alpha emitters. Using all of these radionuclides at such maximum permissible levels of impurity as stated in the European Pharmacopoeia, the total contribution from the impurities to the effective dose equivalent is approximately 30% of the effective dose equivalent from 99mTc-pertechnetate. In terms of specific organs, the liver and kidneys can receive doses of 3-4 times and 1-3 times the dose from 99mTc-pertechnetate itself. Although these are worst case calculations, a consistent approach should be reconsidered to limit the additional effective dose equivalent from impurities to e.g. 10% of the effective dose equivalent from 99mTc itself.

Adolescent↗
PubMed1980

Assessment with TLD of radiation exposure to staff during radium insertions in cancer of cervix.

A radiation protection survey has been carried out using TLD to assess the radiation exposure to staff during radium insertions for cancer of the cervix. The staff monitored were the radiotherapist, anaesthetist and operating theatre assistant. The radiotherapist, who received the highest exposure, had on the average 160 muGy (16 mrad) whole body (chest) dose while the finger tip doses were around 600 muGy (60 mrad) from the insertion of 60 mg radium. TLD was found to be convenient and sensitive for this purpose, including estimation of finger-tip doses. It helps to maintain the confidence of the staff that their doses are "as low as readily achievable" and also offers a means of checking improvements in practice where found necessary.

Brachytherapy↗
PubMed1976

A modified geometric factor approach to internal gamma ray dosimetry.

In internal gamma-ray dosimetry, the conventional geometric factor approach, where the "effective absorption coefficient" is taken as 0 or 0-028 cm-1, irrespective of source energy, leads to significant errors especially in the low energy region. An ettempt has been made in this paper to modify the approach to increase the accuracy of calculation and to extend its usefulness to low energies while retaining its inherent simplicity. The modification consists in replacing the effective absorption coefficient by the attenuation coefficients appropriate to the source energies and taking into account the effects due to multiple scattering by using point source build-up factor. The method has been applied for the particular case of dosimetry of a sphere. Comparison of the results obtained by this method with those got from Monte Carlo computations indicates excellent agreement at higher energies and a departure of around 15 per cent only at lower energies (as against a variation of 400 per cent when conventional geometric factor approach is used).

Absorption↗
PubMed1976

A modified chair geometry for whole body counting.

In the Marinelli chair, a geometry widely used in whole body counting, the lower part of the leg is seen quite inefficiently by the detector. The present paper describes an attempt to modify the standard chair geometry to minimise this limitation. The subject sits crossed-legged in the "Buddha Posture" in the standard chair. Studies with humanoid phantoms and a volunteer sitting in the Buddha posture show that this modification brings marked improvement over the Marinelli chair both from the point of view of sensitivity and uniformity of spatial response.

Humans↗
PubMed1975

A preliminary study of iron absorption by whole body counting and correlation with DFO excretion.

A preliminary study of iron absorption by whole body counting was carried on a group of 16 women. The cases included 8 patients suffering from iron deficiency anaemia and various infections as well as 8 healthy controls. High iron absorption is associated with iron deficiency, these changes being more marked in iron deficient controls than in those with infection or malignancy. In iron deficient controls results of whole body counting correlate very well with other haematological investigations.

Anemia, Hypochromic↗