Ionization chamber used for medical X-ray apparatus

The utility model discloses an ionization chamber used for a medical X-ray apparatus. The ionization chamber comprises an electrode layer and a preamplifier, wherein the electrode layer includes a positive electrode layer and a negative electrode layer which are oppositely arranged in parallel, a cavity is arranged between the electrode layers and one side of the electrode layer is provided with the preamplifier. The electrode layer also includes a carbon electrode layer and a soft metal electrode layer and can be arranged in multiple layers and in parallel to form a plurality of electric fields. The cavity between the electrode layers can be divided into a plurality of cavities by baffle plates and is filled with air. Direct current voltage is applied between the electrode layers to form the electric field. When X-ray irradiates the cavity, the air molecules are ionized and form feeble current in the electric field between the electrode layers, the cavity between the electrode layers forms a sensing area and after the ionized current is collected by the electric field in the sensing area, the ionization current is integrated into direct current voltage through the preamplifier. The direct current voltage value is the function value of X-ray dosage, and the direct current voltage is sent as an output signal to an automatic exposure control system of the X-ray apparatus to realize automatic exposure.