What type of dosimeter is commonly used for the calibration of electron beams?

The ionization chamber is commonly used for the calibration of electron beams because it effectively measures the air ionization produced by ionizing radiation. This device works by collecting the charged particles created when radiation ionizes the air within a sealed chamber. The amount of ionization is directly proportional to the radiation exposure, making ionization chambers precise and reliable for dose measurements.

In the context of medical dosimetry, accurate calibration of treatment beams is critical to ensure that patients receive the correct radiation dose. Ionization chambers are particularly valuable in this application due to their ability to provide accurate and reproducible measurements in various radiation fields, including electron beams, which are often used in radiation therapy for treating superficial tumors.

Other devices listed, such as thermophotometers, temperature sensors, and Geiger counters, are not suited for this specific task. Thermophotometers do not measure ionization but rather thermal radiation; temperature sensors are not designed to measure radiation exposure; and Geiger counters, while useful in detecting radiation, are less accurate for quantitative dose measurement compared to ionization chambers.