Roentgen is the conventional unit used to measure exposure to which type of radiation?

Roentgen is the conventional unit used to measure exposure to which type of radiation?

• A. Alpha and beta
• B. Gamma and x-ray
• C. Neutron
• D. All ionizing radiation

Answer: (B)

Roentgen is a unit of exposure, defined by the ionization it produces in air when exposed to ionizing radiation. It was specifically established for photons—X-rays and gamma rays—so the amount of charge generated per kilogram of air under standard conditions characterizes the exposure. Alpha and beta particles, as well as neutrons, interact with matter in different ways and aren’t described by this exposure measure, which is why roentgen isn’t used for them. In modern terms, exposure is expressed in SI units like coulombs per kilogram (C/kg), with dose and dose-equivalent quantities (such as Gy and Sv) used for biological impact. The best choice reflects that roentgen was tied to ionization from X-ray and gamma radiation.

Roentgen is a unit of exposure, defined by the ionization it produces in air when exposed to ionizing radiation. It was specifically established for photons—X-rays and gamma rays—so the amount of charge generated per kilogram of air under standard conditions characterizes the exposure. Alpha and beta particles, as well as neutrons, interact with matter in different ways and aren’t described by this exposure measure, which is why roentgen isn’t used for them. In modern terms, exposure is expressed in SI units like coulombs per kilogram (C/kg), with dose and dose-equivalent quantities (such as Gy and Sv) used for biological impact. The best choice reflects that roentgen was tied to ionization from X-ray and gamma radiation.