[en] The manifold increase in production, and ease of availability of radioisotopes in India have been responsible for a tremendous increase in use of radioisotopes in industrial radiography during past fifteen years. Among various applications of radioisotopes the industrial radiography involves a large potential risk of occupational radiation exposures. The dose records of past fifteen years in respect of all radiation workers maintained by the Personnel Monitoring Group of Division of Radiological Protection of the Bhabha Atomic Research Centre, Bombay, have been analysed. Analysis of excessive exposure (exceeding 400 mrem/fortnight) reveals that this figure is increasing at an alarming rate among the radiation workers of this category. In spite of various regulatory controls the dose per person per week has remained higher as compared to the same in other categories. This combined with the increase in number of radiation workers every year would soon contribute significantly to the per capita dose for radiation workers. Use of adequately shielded fool-proof remote control equipment and training of all personnel in safe handling of radiation sources seem to be the only solution to arrest the rate of increase in personnel exposures of this category. (auth.)

[en] A countrywide personnel monitoring programme has been carried out by the Division of Radiological Protection, Bhabha Atomic Research Centre in India, since 1957. The exposure records of radiation workers in industrial radiography during the year 1978 have been analysed and attempts are made to study their concurrence with the log normal distribution assumed by the ICRP in stipulating the system of dose limitation. The data is compared with similar results of various other countries. The life time exposures of these workers are also analysed and compared with those in other countries. The analysis leads to a conclusion that the exposure distribution does not conform to the recommended ICRP guidelines although average exposure in the group is within the limits envisaged. (author)

[en] In the light of recent developments in the design and sophistication of TL and RPL dosimetry systems for personnel monitoring, the place of photographic film method is analysed. In controlled areas where a health physicist or a radiological safety officer evaluates the personnel exposures, TL and RPL dosimeters provide the best choice on the basis of their better precision of dose measurements. However, in uncontrolled areas such as medical radiology departments and industrial radiography installations, the information content of a photographic film which helps in almost all cases of high exposures to decide the genuineness of exposure, outweighs the dosimetric characteristics, and the film method appears to be the best choice. It is recommended that developing countries starting a personnel monitoring programme in a centralized place, should use photographic film badges to bring back information regarding the working habits in addition to dose estimates of the individuals concerned. Analysis of 62 cases of fortnightly exposures in excess of 5 rem encountered during 1973 in a personnel monitoring service using photographic films, revealed that 54 cases were non-genuine exposures. (author)

No abstract available

[en] A serious drawback of the film badges used in personnel monitoring is the latent image fading often as high as 95% when they are subjected to extreme climatic conditions such as high humidities and temperatures. Current data on latent image fading in personnel monitoring films of various brands of manufacturers (Kodak, Agfa-Gevaert, Du Pont) are summarized. If individual film packs are hermitically sealed in polythene envelopes, fading is reduced to 20%. Studies were, therefore, conducted on Kodak type 2 films to observe the radiation response of films subjected alternatively to humid (20deg C and 90% r.h.) conditions for 8 hours and dry (20deg C and 30 to 40% r.h.) conditions for 16 hours with a view to find out a practicable and simple method to minimise the error due to fading. The films were then exposed to 600, 1200, 2400 and 4800 mR of radium-226 gammas after one week of storage and replaced in their experimental conditions. The films were processed after zero, one and two weeks of their storage in their respective conditions. Dose versus density curves of films were plotted. A fading less than 10% is shown for a storage period of two weeks. It is also suggested that films be kept in a desiccator having dry silica gel crystals during the periods when they are not being worn by the radiation workers. (M.G.B.)

No abstract available

[en] The excessive exposures (i.e. exceeding 400 mrems per fortnight) of diagnostic X-ray workers revealed under the countrywide personnel monitoring programme in India have been analysed. The analysis covers the data collected over a period of ten years during 1965-1974. The radiation workers in medical X-ray diagnostic group receiving an excess dose are found to be less than 1%. Each case of the excess dose is throughly investigated and nongenuine cases are separated and causes for genuine excessive exposures are traced. The causes and the corrective measures are enumerated. (M.G.B.)

[en] The Division of Radiological Protection of the Bhabha Atomic Research Centre, Bombay, provides a countrywide personnel monitoring service to the medical, industrial and research institutions in which radiation sources are used. In 1976, the above service covered 12475 radiation workers in 1806 institutions. 356 cases of excessive exposure (fortnightly doses of 400 mrems and above) were detected in medical institutions. These cases were further investigated as to their genuineness. A number of them were found to be non-genuine. Remedial actions were suggested in case of genuine cases to the concerned institutions. It is also noted that a number of institutions failed to respond to the investigatory letters. (M.G.B.)

[en] A multi-filter cassette designed and developed for personnel monitoring of radiation workers is described. This cassette incorporates six filters; 1 mm Cd, 1 mmPb, 1 mmCu, 0.15 mm Cu, 1 mm plastic and open window. The aim of bis multi-filter system is to identify the type or types of radiation to which a person is exposed and thus to avoid the normal errors encountered in film dosimetry because of the frequent absence of definite information on the quality of the incident radiation. The advantage of this multi-filter system is that it can be used for monitoring X-rays of all qualities, gamma rays, beta particles, and thermal neutrons. Experience has shown that the ready identification of the type or types of radiation to which a person is exposed is an extremely Important step In limiting future exposures. The film used is the Kodak PM type 2, which Incorporates two emulsions of widely different sensitivities, thus enabling the coverage of a wide range of exposures. The dose ranges covered by this system are 10 mrem to 1000 rem for gamma rays, 1 mrem to 50 rem for low-energy X-rays and 15 mrem to 1500 rem for beta particles. Thermal-neutron doses up to 200 rem can be measured by this system when such thermal-neutron exposures occur in conjunction with gamma exposure, as in a reactor environment. A separate Kodak type A film In a separate holder is used for estimating fast-neutron doses up to about 5 rem. Problems such as the minimum doses measurable, the accuracy of dose estimation, and dose estimations In cases of mixed radiation exposures, are discussed. The methods followed in the maintenance of dose records are also mentioned. These records have been analysed to obtain the radiation dose per week per worker for each institution In India. Yearly data of institutions show a gradual lowering of the occupational exposure levels. (author)

[en] Thermoluminescent (TL) phosphors embedded in PTFE matrix are being increasingly used in personnel monitoring. In India CaSO₄:Dy - PTFE discs are used for routine personnel monitoring. However, the sensitivity of these discs decreases after a few cycles or reuse, mainly because of the deterioration in their optical properties and curling of the dosemeter discs during repeated read outs. Studies were undertaken to increase the useful life of these dosemeters by imparting them to 400degC - 1 hr. treatment in an air oven after treating them with acetone and KOH solution. It was observed that this treatment improves their sensitivity to a large extent due to improvement in their optical properties. These treated discs also show negligible curling in their subsequent reuse, hence increasing the useful life of the dosemeters considerably. (author). 3 figs., 9 refs