A technique for high-sensitivity alpha autoradiography of bronchial epithelium tissue

A technique for low-level alpha-particle autoradiography of bronchial epithelium utilising the plastic track detector, CR-39, is described. This plastic is new to the field of nuclear track detection and is very sensitive to alpha-particles. The recording properties of CR-39 for alpha-particles are described in detail and the technique for autoradiography discussed. This technique includes two methods of background reduction enabling activities as low as 2 alpha-particles cm-2 to be detected. The location of the point of emission of an alpha-particle from the tissue surface can be determined to an accuracy of a few micrometers. Determination of the lower limit to the energy of individual alpha-particles is possible from measurements of their range in the plastic. Examples are given of the determination of the microdistribution of alpha-particle active nuclei in bronchial tissue including the observation of two 'hot-spots' in the epithelium sample which are attributed to the presence of small particles of uranium with its daughter products.