Which factors are needed when calibrating ion chambers?

Calibrating ion chambers is a crucial process in radiation therapy and involves ensuring accurate measurements of radiation dose. The correct choice includes barometric pressure, volume of the chamber, and temperature, all of which are essential factors in this calibration process.

Barometric pressure must be accounted for because it can influence the density of the air inside the ion chamber, which in turn affects the ionization process. A consistent calibration requires that any variations in atmospheric pressure be corrected to ensure that measurements are reproducible and accurate.

The volume of the chamber is significant as it affects the amount of air that is ionized when radiation passes through. Larger chambers may require different calibration factors than smaller ones, as volume directly impacts the chamber's response to radiation.

Temperature is another critical factor as it influences the behavior of air and other gases within the ion chamber. Changes in temperature can lead to changes in pressure and density, which, if uncorrected, would lead to inaccuracies in dose measurements.

By including these three factors—barometric pressure, volume of the chamber, and temperature—calibration can maintain its accuracy and reliability, directly impacting the effectiveness and safety of radiation therapy treatments.