Some Factors Affecting the Results Obtained with Kodak AR.10 Stripping Film in Autoradiography

Welton, M. G. E.

doi:10.1080/00223638.1969.11737502

Cited by 3 publications

(2 citation statements)

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“…We have not been able to make accurate visual grain counts with concentrations above about 0.8 grains/pm2. Mazia et al (1955) found that within limits the grain count was proportional to the absorbance, and Welton (1969) found that up to 1 grain/pm2 the absorbance was proportional to the grain count to within 5%. Dormer (1967aDormer ( , 1967b also recognized that at relatively low exposures the absorbance (' Schwarzung') is proportional to the number of silver grains, and he found experimentally that, with AR.10 film, plots of absorbance and of reflectance against time of exposure gave closely parallel lines up to absorbance of about 0.5 (corresponding to a grain count of about 7.0/pm2).…”

Section: (5)mentioning

confidence: 99%

“…There is accordingly no simple and general relationship between exposure (i.e. intensity of irradiation multiplied by time) and blackening of the emulsion, but the problem can be considerably simplified if we ignore reciprocity failure due to fading of undeveloped grains (Appleton, 1966; Welton, 1969), and assume in the first instance that the emulsion consists of a single layer of non-overlapping and relatively uniform silver grains, each of which can be activated by a single quantum of energy. Such ' single-hit ' activation is found with medium-energy electrons and various types of ionizing radiation (Digby, Firth & Hercock, 1953; Dudley, 1954;Golden & Tochilin, 1959;Valentine, 1966;Vernier, 1969), while 'multihit' activation occurs with exposure to visible light.…”

Section: Relationship Of Exposure Grain Count Reflectance Ratio Andmentioning

confidence: 99%

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Quantitative autoradiography: an evaluation of visual grain counting, reflectance microscopy, gross absorbance measurements and flying‐spot microdensitometry

Goldstein

Williams

1971

Journal of Microscopy

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S U M M A R YKodak AR.10 and Ilford G5 autoradiographs of a variety of radioactive resin standards and labelled cell preparations were investigated by visual grain counting, reflectance microscopy, gross (non-scanning) absorbance measurements and integrating microdensitometry (the last using the Vickers M85 flying-spot instrument).The reflectivity of silver grains is affected by the type of radiation to which the emulsion was exposed, the conditions of development and other factors. Reflectance results in arbitrary machine units were converted to absolute units by comparing them with results obtained under identical experimental conditions on fully-blackened standard autoradiographs.With relatively low grain counts, the exposure is approximately proportional to the visual grain count, the reflectance, the gross absorbance and the integrated absorbance. With a fractional coverage of emulsion by developed grains of more than about 0.4, or absorbance more than about 0.22 (corresponding with Kodak AR.10 to grain densities of more than about 1.5/pm2), the exposure remains directly proportional to the absorbance and the integrated absorbance; experimental observations confirmed the theoretical prediction that the apparent fractional coverage, as measured by reflectance microscopy, is approximately equal to unity minus the antilog of minus the absorbance.Visual grain counting is reliable in the range 0.01-0.4 grains/pm2 (about 30 grains/ 10 pm diameter cell), and although tedious is widely applicable. Reflectance measurements are objective and relatively rapid, and are useful with grain counts up to about 150 grains/cell, but results may be affected by staining of the emulsion or by fluorescence of the emulsion or specimen. Both gross and flying-spot absorbance measurements are directly proportional to the exposure over a large range. Gross absorbance measurements are applicable only to extended, homogeneous autoradiographs, while integrating, flying-spot measurements may be used also with discrete and non-uniform specimens. Both absorbance methods are best applied to unstained preparations.

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Section: (5)mentioning

confidence: 99%