Depth of ionization chamber in water.

The device developed by the authors and described here enables the user to measure the depth from the water surface to the point of measurement for a cylindrical ion chamber with a waterproof plastic cap in a water phantom, free of surface-tension error with a high precision. The device seeks vertical orientation and provides the convenience of hands-free operation. The measurement process is simple and quick with a precision of 0.1 mm. (The device is currently available as a 'water phantom depth gauge' from Nuclear Associates, Division of Victoreen Inc., Clare Place, NY, USA.)