Deposition, Retention and Dosimetry of Inhaled Radioactive Substances

Abstract

As the opening words of its preface state, `The development of a respiratory tract model which accurately reflects reality is a difficult and complicated effort'. Many factors contribute to this. For radiological protection purposes, the respiratory tract has to be considered both as a target organ for damage and as a route of entry to the systemic circulation from which activity may deposit in and irradiate other organs. However, both the radiosensitivity of the tissues and the clearance characteristics of deposited material vary greatly between the different regions of the respiratory tract. Furthermore, the pattern of deposition of inhaled activity between the respiratory tract regions depends on the size of the inhaled particles, on the dimensions of the airways and on the airflow patterns within them. In view of the importance of the inhalation route of intake not only for radioactive substances, but also for toxic materials in the workplace and the environment in general, deposition and clearance of inhaled particles and vapours have been, and continue to be, studied widely.