Patent ID: 7605365

Claim:
A water phantom structure with fixed water level for measuring dose of ionizing radiation absorbed to water, comprising: a tank, configured with an opening on top thereof for receiving a water solution; at least a servo motor, for providing a driving force; an ionization chamber, connected to a static electrometer which is further connected to a high voltage source for using the high voltage of the high voltage source to cause a current to be generated in the ionization chamber as soon as the ionization chamber is irradiated by a radiation, causing an ionization reaction in the ionization chamber, while enabling the static electrometer to measure a signal relating to the current of the ionization reaction; a clipping device, for clasping the ionization chamber and being connected to the at least one servo motor in a manner that it is driven to move by the driving force of the servo motor and thus bring along the ionization chamber to move in the tank accordingly; and a lid, capable of being placed in the tank while floating on the water solution for defining a reference water level thereby; wherein, the area of the reference water level defined by the lid is larger than the allowable moving range of the ionization chamber.