Image reconstruction for a radiation-field mapping system

A prototype device for producing an iso-dose map of the radiation field due to an arbitrary source distribution has been constructed. Such a device would automate radiation surveys, greatly reducing expenditures in person-hours and person-rems for radiation workers. An automated survey system would be very useful in nuclear power plants, radioactive waste disposal sites, medical irradiation facilities, and radiochemical laboratories. Because of the authors interest in high-radiation fields, the system employs a pair of collimated ionization chambers mounted on a scanning carriage. Ionization chambers were chosen for their durability in a hostile environment, such as a boiling water reactor dry well. The measurement process is composed of a series of scanner rotations and translations and is similar to that used for medical computed tomography imaging. A simple trigonometric algorithm was used to produce a two-dimensional map from radiation intensity and position data. These maps, although providing proof of principle, were highly artifacted due to the small number of scanning carriage locations constrained by the small size of the hot cess in which the device is operated