Apparatus and system

An apparatus comprising:

• a conversion element configured to accumulate a charge for generating an image;
• a communication unit configured to transmit, to an external apparatus, a permission signal permitting emission of radiation;
• a reading unit configured to read the charge accumulated in the conversion element and generate a signal;
• and
• a generation unit configured to generate image data from the generated signal,
• wherein the reading unit generates a first correction signal by reading a charge accumulated in the conversion element during a first reading time before transmission of the permission signal, generates a radiation signal by reading a charge accumulated in the conversion element based on the emission of the radiation after the transmission of the permission signal, and generates a second correction signal by reading a charge accumulated in the conversion element not based on the emission of the radiation during a second reading time after the transmission of the permission signal,
• wherein the generation unit generates image data by performing a correction process on the radiation signal using the first or second correction signal, and
• wherein the second reading time is shorter than the first reading time.